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This letter presents the theoretical investigation by a transmission line model and the physical implementation of a novel frequency reconfigurable microstrip antenna with switchable states. More specifically, by using voltage‐controlled PIN diodes, the antenna can be switched between a radiation state and a low‐scattering state. In the radiation state, the operation frequency of the antenna can be electrically modified between 1.5 and 2.3 GHz by acting on the voltage applied to the varactors. In the low‐scattering state, the antenna achieves a significant in‐band radar cross section reduction, with a maximum value of 26.7 dB. The proposed antenna is fabricated and measured. The validity of the proposed strategy is verified by the good agreement between simulated and measurement results. The antenna designed by the proposed approach has great advantages in the radiation performance, aperture size, profile height and design freedom. This work indicates the feasibility of employing the reconfiguration technique to mnipulate the scattering features of an antenna without deteriorating its radiation characteristics. [ABSTRACT FROM AUTHOR]

A miniaturized edge-fed multi-band wideband (WB) sensor complementary split ring resonator (CSRR) and two folded pedal arms loaded antenna for wireless, ISM, military, Radar, and satellite applications is fabricated, tested, and investigated. The reduced ground plane at the bottom to makes the gain positive and leads to improvement in the radiation efficiency. Loading of antenna patch with two folded bicycle pedal-shaped arms results in an increased total electrical length and hence antenna could be tuned up to higher frequency bands. The appended two folded pedal arms enhance the value of gain and CSRR loading introduces additional resonant frequencies below −10dB reflection coefficient. The symmetrical ground width compression results in total antenna size miniaturization to 43.33% concerning the conventional circular microstrip antenna designed at a frequency of 2.45GHz. The antenna has a bidirectional radiation pattern with a gain of 5.21dBi and a radiation efficiency of 90.50%. The antenna exhibits four bands (2.13–2.58GHz), (2.77–3.89GHz), (5.65–6.56GHz), and (7.77–12.98GHz) within a frequency sweep of 1–15GHz, therefore it, is the most suitable element for Bluetooth, PCS, ISM band, 3G/4G/5G, Wi-MAX/WLAN/ Wi-Fi, and wireless, satellite, military, and RADAR applications. These bands are frequency reconfigured by two BAP64-02V PIN diodes in the pedal-arms fold locations with four switching combinations. The measured (frequency sweep: 1–23GHz) and simulated antenna reflection coefficient values are found in match except for a frequency range of 12–14 GHz. The antenna was fabricated on a low-cost FR-4 that holds well <12 GHz frequencies, and >12 GHz frequencies values this shows nonlinear and frequency dispersion. [ABSTRACT FROM AUTHOR]

Maintaining acceptable radiation performance over the entire operation bandwidth is a significant challenge in development of a miniaturised reconfigurable antenna. To address this issue, a new Substrate Integrated Waveguide (SIW) based reconfigurable antenna using slow wave structure is presented in this study. The proposed SIW antenna is based on a layered construction with metallic blind vias connecting to ground plane of SIW. The multi-layer structure of SIW with blind vias helps to separate magnetic and electric fields in the SIW cavity. Thus, a slow wave effect is also utilised and it leads to 36% reduction in the antenna size as compared to conventional SIW cavity. To attain the polarisation and frequency reconfiguration, a cross slot is introduced in the top metallic layer of the SIW cavity and four PIN diodes are connected into the cross-slot arms. Experimental results exhibit frequency reconfigurability in different operating regions with resonant frequencies 4.35, 5, 5.8, 6.4, and 9.6 GHz. The polarisation reconfigurability of the proposed antenna is achieved at 5 GHz with LP/RHCP/LHCP. The proposed antenna exhibits 3-dB axial ratio bandwidth of 4.8 to 5.2 GHz with peak gain of 4.2 dBi. [ABSTRACT FROM AUTHOR]

Wireless communication systems have grown rapidly, moving towards being highly compact, intelligent, and flexible to adapt to changing operating requirements. Multifunctional and highly versatile antennas are key in this development to ensure system quality. Reconfigurable antennas, particularly regarding polarization, allow frequency reuse and enable the mitigation of fading effects. This work presents a square microstrip patch antenna operating in the ISM 5.8 GHz band with reconfigurable polarization by controlling its feeding. This antenna has four different states through the application of a symmetrical DC voltage that controls an RF circuit with PIN diodes. As a result, the microstrip patch can operate with three different polarizations: linear polarization and both circular polarizations (right-handed and left-handed). The antenna was fabricated to validate the proposed concept. The good agreement between the measurement and the simulation results was possible to observe regarding its polarization behaviour, impedance adaptation and radiation pattern. [ABSTRACT FROM AUTHOR]

A reconfigurable transmission metasurfaces (RTMs) excited by a multiple‐input multiple‐output (MIMO)(RTMs‐MIMO) antenna is designed to implement multi‐domain metamaterial computational imaging (MCI). Based on the receiver‐transmitter metasurfaces structure, four PIN diodes are applied to control the operating state of the RTMs. It enables arbitrary switching among four polarization transmission waves. A reverse‐induced current can be generated by adjusting the PIN diodes in the symmetrical position, resulting in a perfect 1‐bit phase modulation with a 3dB‐loss bandwidth of 15.38~19.89 GHz. A microstrip antenna with mushroom‐shaped parasitic patches is employed to implement the MIMO feeds. The ‐10dB bandwidth of MIMO antenna is compatible with the RTMs, and the maximum envelope correlation coefficient of 0.16 demonstrates good isolation between the MIMO feeds. In the MCI system constructed by the RTMs‐MIMO antennas, a transmission matrix H can be achieved by MIMO space beams, metasurfaces phase, metasurfaces polarization, and frequency modes. The correlation coefficient µg = 0.018 is achieved by the multi‐domain integration, allowing H to be highly non‐correlated. Based on the detection results of H, an imaging result with a relative reconstruction error of 0.372 is achieved. The designed MCI system therefore has unparalleled application prospects in the broad field of medical and military detection. [ABSTRACT FROM AUTHOR]

Technology is advancing daily, and it has impacted almost every aspect of our lives. We show that growth in the number of miniaturized communications systems that are covering different wireless services can achieve a wide frequency range. The present work aims to propose a new rigorous formulation to model a reconfigurable array system used for different wireless applications. The studied structure consists of a reconfigurable antenna array composed of parallel microstrip antennas excited by localized voltage sources and commanded by located PIN diodes. Diodes are used to adjust the length of the radiating element in order to shift the resonant frequency. The proposed formulation consists to combine the moment method and generalized equivalent circuit's method (MoM-GEC) to model the antenna array. The PIN diode is considered in the mathematical formulation by an impedance surface model. The input impedance, the reflection parameter ( S 11 ) and the current distribution density obtained with this method are presented and discussed. The results were in close agreement with those obtained by software simulation. The obtained results offer the possibility to generate various modes governed by a decision tree. Thus, these modes are related to different resonant frequencies suitable for RFID, WiMax and WLAN applications with a large bandwidth reaching 526 MHz. [ABSTRACT FROM AUTHOR]

We propose a miniaturized frequency-reconfigurable multiband antenna with bandwidth enhancement. The main radiating patch is shorted from one edge to reduce the antenna footprint. An inverted U-shape microstrip line is integrated onto the antenna structure to excite more resonant frequencies. Indeed, by shorting the U-shape's arms, seven frequency bands can be created and controlled. The activation of the two p-i-n diodes is ensured by employing a simple symmetrical DC bias network. Furthermore, by adjusting the arms' lengths, two resonances are combined to enhance the working bandwidth. Measurements reveal that the antenna resonates around the operating frequencies of 2.91 GHz, 3.55 GHz, 3.69 GHz, 3.83 GHz, 4.14 GHz, 4.18, and 4.24 GHz. The antenna exhibits stable patterns, with a measured peak gain and efficiency of 5.5 dBi and 86%, respectively. The antenna is compact; thus, it is recommended in wireless systems requiring multiband function with stable patterns and a reduced area. [ABSTRACT FROM AUTHOR]

Purpose: In wireless communication system, use of multiple antennas for different requirements of system will increase the system complexity. However, reconfigurable antenna is maximizing the connectivity to cover different wireless services that operate different frequency range. Pattern reconfigurable antenna can improve security, avoid noise and save energy. Due to their compactness and better performance at different applications, reconfigurable antennas are very popular among the researchers. The purpose of this work, is to propose a novel design of S-shaped antenna with frequency and pattern diversity. The pattern and frequency reconfiguration are controlled via ON/OFF states of the PIN diode. Design/methodology/approach: The geometrical structure of the proposed antenna dimension is 18 × 18 × 0.787 mm3 with εr = 2.2 dielectric constant. Three S-shaped patches are connected to a ring patch through PIN diodes. The approximate circumference of ring patch is 18.84 mm and length of patch is 5 mm, so approximate length of radiating patch is 14.42 mm and effective dielectric constant is 1.93. Conductor backed coplanar waveguide (CPW) is used for feeding. The proposed antenna is designed and simulated on CST microwave studio and fabricated using photolithography process. Measurements have been done in anechoic chamber. Findings: Antenna shows the dual band operation at 2.1 and 3.4 GHz frequency. The first band remains constant at 2.1 GHz resonant frequency and 200–400 MHz impedance bandwidth. Second band is switched at seven different resonant frequencies as 3.14, 3.45, 3.46, 3.68, 3.69, 3.83 and 3.86 GHz with switching of the diodes. The −10 dB bandwidth is more than 1.4 GHz. Research limitations/implications: Pattern reconfigurability can be achieved using mechanical movement of antenna easily but it is not a reliable approach for planar antennas. Electronic switching method is used in proposed antenna. Antenna size is very small so fabrication is very crucial task. Measured results are deviated from simulation results due to fabrication error and effect of leads of diodes, connecting wires and battery. Practical implications: The reconfiguration of the proposed antenna is controlled via ON/OFF states of the three PIN diodes. The lower band of 2.1 GHz is fixed, while second band is switched at five different resonant frequencies as 3.27, 3.41, 3.45, 3.55 and 3.88 GHz, with switching of the PIN diodes with all state of diodes and exhibit pattern reconfigurability at 2.1 GHz frequency. At second band center frequency is significantly changed with state of diodes and at 3.4 GHz pattern is also changed with state of diodes, hence antenna exhibits frequency and pattern reconfigurability. Originality/value: A novel design of pattern and frequency reconfigurable antenna is proposed. Here, work is divided into two parts: first is frequency reconfiguration and second is radiation pattern reconfiguration. PIN diodes as switch are used to select the frequency band and reconfigure the radiation pattern. This proposed antenna design is novel dual band frequency and pattern reconfigurable antenna. It resonates at two distinct frequencies, i.e. 2.1 and 3.4 GHz, and has a pattern tilt from 0° to 355°. The conductor backed CPW feed technique is used for impedance matching. [ABSTRACT FROM AUTHOR]

A circularly polarized (CP) and frequency reconfigurable microstrip antenna with loading inductive is presented in this paper. The designed antenna is comprised of a radiating patch, four short-circuited grounded metal posts, and four coupling branches. Each coupling branch has an end that is coupled to the shorted ground post and is also connected to the parasitic branches by means of a group of PIN diodes. By controlling the state of the PIN diodes connected to each parasitic branch, the working resonant frequency of the antenna can be changed. In order to further understand the mechanisms of operation of the antenna, the equivalent circuit model was built, and the circuit model of the antenna was analyzed, and this analysis was used for the development of the frequency reconfigurable microstrip patch antenna. Furthermore, the parameters of specific equivalent circuits can be solved by the three lengths of branch. Meanwhile, the calculated results derived from the given resonant frequency formula for the antenna are in good agreement with the simulation results of the antenna. Simulated results for the input impedance of the antenna are also in good agreement with the calculated values for the equivalent circuit. Finally, the antenna is fabricated and measured, and the measured results show that the antenna can not only achieve frequency reconfiguration at 1.14 GHz, 1.21 GHz, and 1.39 GHz but also accord well with the simulation value, while maintaining a compact size. [ABSTRACT FROM AUTHOR]

In this paper, a low-cost resin-coated commercial-photo-paper substrate is used to design a printed reconfigurable multiband antenna. The two PIN diodes are used mainly to redistribute the surface current that provides reconfigurable properties to the proposed antenna. The antenna size of 40 mm × 40 mm × 0.44 mm with a partial ground, covers wireless and mobile bands ranging from 1.91 GHz to 6.75 GHz. The parametric analysis is performed to achieve optimized design parameters of the antenna. The U-shaped and C-shaped emitters are meant to function at 2.4 GHz and 5.9 GHz, respectively, while the primary emitter is designed to operate at 3.5 GHz. The proposed antenna achieved peak gain and radiation efficiency of 3.4 dBi and 90%, respectively. Simulated and measured results of the reflection coefficient, radiation pattern, gain, and efficiency show that the antenna design is in favorable agreement. Since the proposed antenna achieved wideband (1.91–6.75 GHz) using PIN diode configuration, using this technique the need for numerous electronic components to provide multiband frequency is avoided. [ABSTRACT FROM AUTHOR]

This paper presents a compact multifrequency reconfigurable patch antenna in terms of design and fabrication for operating in the S and C bands of the RF spectrum, which are overwhelmed by wireless applications. Reconfiguration is achieved by using a single PIN diode on the ground plane. By varying the voltage applied to the diode, three modes can emerge, exhibiting main resonant frequencies at 2.07, 4.63, and 6.22 GHz. Resonance switching requires a voltage of less than 0.9 V. The antenna fabricated on an FR-4 substrate, with a volume of 70 × 60 × 1.5 mm3, has a radiating patch element of a rectangular ring shape. The proposed low-cost antenna is easily implemented in a typical university lab-based environment. The total bandwidth for the three modes is close to 1 GHz, while the voltage standing wave ratio (VSWR) of the fabricated version of the antenna does not exceed 1.02, and the return loss is well below −40 dB for the three primary resonant frequencies. [ABSTRACT FROM AUTHOR]

In this work, an electronically reconfigurable dual-band dual-mode microstrip ring antenna with high isolation is proposed. Using characteristic mode analysis (CMA), the physical characteristics of the ring antenna are revealed, and two modes are appropriately chosen for operation in two sub-6 GHz "legacy" bands. Due to the inherent orthogonality of the characteristic modes, measured isolation larger than 37 dB was achieved in both bands without requiring complicated decoupling approaches. An integrated electronically reconfigurable matching network (comprising PIN diodes and varactors) was designed to switch between the two modes of operation. The simulated and measured results were in excellent agreement, showing a peak gain of 4.7 dB for both modes and radiation efficiency values of 44.3 % and 64 % , respectively. Using CMA to gain physical insights into the radiative orthogonal modes of under-researched and non-conventional antennas (e.g., antennas of arbitrary shapes) opens the door to developing highly compact radiators, which enable next-generation communication systems. [ABSTRACT FROM AUTHOR]

In this paper, we propose a novel method for obtaining wideband spectral information of the target in microwave imaging systems by using broadband frequency reconfigurable printed transceivers. The proposed transceiver is composed of two embedded stacked microstrip antenna configurations operating in C-band (5.5–8.5 GHz) and X-band (8.5–11.5 GHz) with each having 3 GHz bandwidth. The transceiver switches between the two configurations (and thus frequency bands) using PIN diodes and collects response of the antenna in the presence of the target, in both the operating bands. This information is then combined to obtain wideband spectral information of the target from 5.5 to 11.5 GHz to achieve improved image reconstruction. The proposed reconfigurable transceiver has advantage over traditional broadband transceivers (those have slots/meandering at ground plane to achieve wideband response) that it has unidirectional radiation patterns throughout its band of operation. Hence the imaging system is implemented without the absorbers. This keeps the system compact and inconspicuous when installed for security applications. Here, a bistatic system is employed with two-dimensional target scanning performed in a real outdoor environment. [ABSTRACT FROM AUTHOR]

In this paper, a compact tuned reconfigurable microstrip antenna for fifth generation (5G) mobile communications is designed to operate at 28 GHz or 38 GHz or both frequencies. The proposed antenna can be reconfigured by using a group of PIN diodes switches across a slit in the upper traditional patch antenna or through the ground plane side. The tuning between the 28 GHz and 38GHz frequency bands can be achieved through ON/OFF states of the PIN diodes switches. The tuned reconfigurable antenna is simulated using CST software package and then fabricated and measured. The simulated and measured results show good agreement with a little deviation. The proposed tuned antenna is small in size with 18×11.25 mm² overall area. [ABSTRACT FROM AUTHOR]

A novel 3‐bit frequency‐reconfigurable antenna (FRA) with miniaturized dimensions is realized with a meander line. The frequency reconfiguration of the antenna is achieved by introducing N Radio Frequency (RF) PIN diodes into the meander line. The related parts of the meander line with different lengths are bypassed or included into the antenna by switching on or off the diodes, resulting in 2N switchable size lengths of the antenna and equally spaced operating frequencies. A 3‐bit reconfigurable meander‐line antenna (N = 3) is designed, and the simulated and measured results agree well. The antenna provides 8 (23) independent and switchable states, with the operating frequencies covering a wide switchable frequency range from 1.04 to 1.51 GHz and the working bandwidths varying from 80 to 150 MHz. The number of working bandwidth states is maximized, considering the number of switches used. Moreover, the results reveal an acceptable peak gain of 1.59 dBi in terms of the miniaturized total dimension of 0.17 λg × 0.07 λg (λg is the guided wavelength at the lowest working frequency), which is more compact than several published FRAs. [ABSTRACT FROM AUTHOR]

Microstrip antennas have many advantages as they are low-profile, suitable for conformal structure, and integrated with electronic circuits. The antenna characteristics can be easily modified by shape transformation. In this work, a multiband microstrip antenna is developed. The antenna operates in 2.4 GHz, 3.5 GHz and 3.15 GHz reconfigurable as well as tunable modes. A pin diode switch and another varactor diode switch are used for the frequency band reconfiguring and tuning respectively. The switches are integrated into two coupled parasitic transmission lines without disturbing the main radiator structure. Using a pin diode, the operating band is switched between 3.15 and dual 2.4 and 3.5 GHz bands. Simultaneously by applying a reverse bias voltage to the varactor diodes, frequency tuning is done in respective bands. The simulated model of the antenna is fabricated and tested. The measured results are found satisfactory. [ABSTRACT FROM AUTHOR]

A frequency reconfigurable microstrip patch antenna with a combination of an asymmetric armed U-slot and a reversed L-slot etched on a rectangular base patch of 6 GHz resonant frequency designed on an FR4 substrate (ɛ r = 4.4) is presented in this paper. Three RF PIN diodes are positioned at inimitable sites of these slots to achieve frequency reconfiguration. A DC bias circuitry, which includes DC blocking capacitors and RF blocking inductors, is integrated with the antenna structure for switching (ON/OFF) the PIN diodes. Six reconfigurable modes with resonant frequencies at 4.33, 4.63, 5.24, 5.87, 5.96, and 6.29 GHz is obtained with different ON-OFF combinations of these PIN diodes. These reconfigurable resonant frequencies cover two continuous bands from 4.21 to 5.43 GHz and 5.69 to 6.6 GHz and is considered to be useful for the applications like aeronautical radio navigation (4.3 GHz), sub-6-GHz 5G (4.4–5 GHz), WLAN (5.2 and 5.8 GHz) and Wi-Fi 6E (5.925–6.425 GHz). Measured gain of the antenna for all the modes varies between 5.86 dBi and 8.72 dBi. [ABSTRACT FROM AUTHOR]

A compound reconfigurable microstrip antenna has been analyzed and designed using switching a PIN diode to switch between different modes of operating frequencies as well as radiation pattern directions. In this paper, computer simulation technology (CST) software 2020 has been used. Due to the complex calculation of the circular microstrip patch antenna, the proposed design has reduced the complexity by using a structure that is compact, easy to fabricate, cheap to produce, and uses only one PIN diode, while maintaining peak antenna performance. The suggested design is appropriate to operate in two states conditional on biasing the PIN diode. The reconfigurable patch of 31.16 mm × 27.04 mm has a compact size with 1.6 mm of thickness. It functions in both the C band at 7.1 GHz with a shift of radiation pattern direction to 4 degrees, and in the Ku band at 12.5 GHz with a shift of radiation pattern direction to 28 degrees in state 2 where the PIN diode is on state. In addition, the ON and OFF state of the switching PIN diode has been extensively investigated via changing the resistance, inductance, and capacitance values for optimal antenna performance. The proposed reconfigurable circular patch can be implemented to operate in modern communication such as Radio navigation and earth exploration, space operation, earth-to-space satellite communication, 5G applications, and Wireless-Fidelity 7. [ABSTRACT FROM AUTHOR]

This paper presents the design of a frequency reconfigurable monopole microstrip patch antenna for wireless communication applications. The proposed antenna functions in one single-band mode and one dual-band mode, depending on the diode switching configuration. When the diode is in the OFF state, the proposed antenna operates at single band 5.8 GHz (WLAN), and in the ON state, the antenna operates at dual bands 1.8 GHz (GPS/RADAR) and 5.2 GHz (WLAN). To enhance the gain of the proposed reconfigurable antenna, a multilayer frequency selective surface (FSS) reflector is presented. A significant enhancement in gain has been achieved in a low-profile design. The average peak gain of the antenna has been increased from 4 dBi to 6 dBi as a consequence of the use of the FSS reflector. The simulation of the proposed design is carried out using CST (Computer Simulation Technology) based on the FIT (Finite Integration Technique) numerical method. To validate the simulated results, a prototype of the antenna was fabricated and measured using PIN diodes. The simulated and measured results of the proposed antenna exhibit a reasonable agreement. [ABSTRACT FROM AUTHOR]

In this paper, a frequency reconfigurable multiband multiple-input-multiple-output (MIMO) antenna is developed for 5G communication systems. The presented MIMO antenna element consists of a 50 Ω microstrip line, a rectangular monopole divided into two patches, and a partial ground plane. A split-ring resonator (SRR) is introduced into the upper patch to cover multiple 5G application bands, and an RF PIN diode is embedded between the upper and lower patches to enable the frequency diversity feature. In order to design a MIMO antenna with improved inter-element isolation, four antenna elements are orthogonally located with ground planes connected to each other. The antenna design covers the n41/n46/n48/n79 5G application bands. The prototype MIMO antenna is developed on the FR-4 substrate, and the measured results match with the simulated outcomes. The overall footprint of the prototype antenna is 70 × 70 × 1.6 mm3. [ABSTRACT FROM AUTHOR]

This article presents a circular microstrip patch antenna loaded with three complementary split rings (CSRRs) on the ground plane for pattern agility features. The antenna resonated at 5.3 GHz and accommodated the frequency spectrum from 5.1–5.7 GHz for different CSRR combinations. The reconfigurable pattern feature has been produced with three p-i-n diode combinations integrated with the CSRR slot on the ground patch. The CSRR combinations are utilized to change the radiation phase concerning the primary radiating circular patch. The proposed antenna radiation beam can steer from ±15°, 180°, and 0° of the broadside pattern in the elevation plane with a satisfactory gain of 3 dBi. The phase variation for various CSRR combinations concerning the primary antenna is presented. The presented antenna is fabricated on an FR4 substrate and tested in an anechoic environment; the tested results verify the pattern agility of the antenna. The demonstrated antenna is suitable for modern wireless communications like LTE and Cognitive radios. The compact size, simple biasing, and low cost are added advantages of the antenna. [ABSTRACT FROM AUTHOR]

In this study, a compact, reconfigurable, and high-efficiency Long Range (LoRa) patch antenna, which is novel, is presented for Internet of Things (IoT) applications. The antenna is designed to operate at the three major frequencies used for LoRa communication, namely 915 MHz, 868 MHz, and 433 MHz, which are widely employed for global LoRa connectivity. The compact size and impedance matching of the antenna are achieved through the use of meandered radiating patches, a partial ground plane, and a ground plane stub. The antenna is prototyped on a commercially available and cost-effective FR-4 material and measures 80mm×50mm×1:6mm (0:12λ×0:07λ at the lowest resonant frequency), which is smaller than the size of a standard credit card. The antenna utilizes three RF PIN diodes (SW1, SW2, and SW3) for frequency reconfiguration, which are characterized by low insertion loss and fast switching time. The RLC equivalent circuit of the antenna was validated through simulations and measurements, yielding the peak gain and radiation efficiency of 2.1 dBi and > 90%, respectively. These results prove that the antenna is a promising solution for LoRa IoT applications in terms of size, cost, and performance, filling a gap in the existing literature of LoRa MPAs that are typically large, non-reconfigurable, low-gain, and single-band. [ABSTRACT FROM AUTHOR]

This paper presents a compact coaxial-fed square microstrip patch antenna integrated with a beam-steering Partially Reflective Surface (PRS). The proposed design has a two-dimensional (2-D) Fabry-Perot Cavity (FPC) antenna acting as a radiator and the PRS as a beam-steering superstrate operating at 5.5 GHz. The PRS consists of 6 × 6 reconfigurable unit cells etched on Rogers 5880 with a thickness of 1.57 mm. By controlling the switching of PIN diodes in different sections of PRS, beam steering can be achieved up to ±47° in the azimuth plane with a gain of 9.1 dB and 10.2 dB and ± 15° steering in an elevation plane with a measured gain of 9.3 dB and 8.9 dB, respectively. The antenna prototype is 2.56 λ × 2.56 λ at 5.5 GHz, and the measured gain values are around 10 dBi for all the states. The beam is able to radiate at boresight or tilted to 42° in two azimuthal directions and 45° in elevation direction by adjusting the PIN diodes ON/OFF states. The 10 dB impedance bandwidth of 5.4–5.52 GHz is achieved. [ABSTRACT FROM AUTHOR]

Wearable antennas are critical in on-body wireless communications and have piqued scientists' curiosity. Because wearable antennas work so near to the human body, the loading effect caused by body tissue breakdown, along with their high dielectric constants and conductivity, makes developing a high-radiation output antenna challenging. The demand that these antennas be lightweight, low-cost, maintenance-free, and require no setup adds to the problem. In recent years, the demand for wearable devices has skyrocketed. Wearable antennas are utilized in a variety of applications, including wireless body area networks (WBANs), in many circumstances. The patch antenna is one of the primary research goals of wearable antennas for WBAN applications due to the extensive ground plane employed in its construction and its relatively high directionality. In addition to directivity, microstrip patch antennas provide other benefits for on-body wearable applications. The wearable textile ultra-wideband (UWB) antenna's frequency of changes versus gain is set. The maximum gain is about 17.2 dB at 16 GHz. The gain of the frequency of 14 GHz is obtained at 16.8 dB, with a high performance rate. The design in the present paper has low power consumption as a result of achieving gain results of less than 5 dB in most frequency bands from 2 to 16 GHz. While the reflector is present, the size of the reflector is chosen to make the antenna resistant to frequency detuning. When the distance between the monopole and the reflector is lowered, the antenna's frequency decreases. The greater power, the closer the reflector is to the inductive near zone. However, the reflector was chosen to boost the front-to-back ratio of the proposed monopole. The reflection coefficient is derived by varying different resonating frequencies between −19.45 and −16.45 dB. The highest directivity is 11.5 dB and the lowest is 9.8 dB while varying different resonant frequencies. Gain is achieved by varying different resonant frequencies, with a maximum of 17.2 dB and a minimum of 16.2 dB. The effectiveness of varying different resonant frequencies is 45% maximum and 40% minimum. The suggested UWB antenna was found to have an acceptable agreement between models and tests, demonstrating its potential for microwave applications. The directivity, gain, Voltage Standing Wave Ratio (VSWR), and radiation pattern are all performance metrics that are measured. [ABSTRACT FROM AUTHOR]

In this communication, a tunable circularly polarized (CP) antenna with a reconfigurable integrated feed network is proposed for cognitive radio (CR) applications. The integrated feed network is composed of an ultrawideband (UWB) bandpass filter (BPF), a continuously tunable T-shaped resonator, and an L-shaped microstrip line. The feed network employs three p-i-n diodes to switch between different RF paths, resulting in three modes of operation: an UWB mode (3.5–8.5 GHz), a narrowband bandpass (BP) mode and a narrowband bandstop (BS) mode. The continuous tuning range of the BP/BS narrowband mode is realized by two dc-controlled varactor diodes. The stand-alone antenna attains a −10 dB impedance bandwidth of 92.3% (3.5–9.5 GHz), while it attains an axial ratio (AR) bandwidth of 88.3% (3.1–8 GHz) in its wideband mode. The overlapped bandwidth (matching and AR) of the reconfigurable antenna is 78.2% (3.5–8 GHz). The communicating state covers 80% of the sensing spectrum while maintaining CP radiation. The measured peak realized gain values for the wideband mode range from 2 to 3.2 dBic while the maximum gain for the narrowband mode ranged from 1.95 to 3.1 dBic. The measured results show that the proposed filtenna is suitable for UWB CR systems. [ABSTRACT FROM AUTHOR]

The proposed manuscript represents the novel approach to achieve the frequency reconfigurability of the microstrip patch antenna. The tunability is achieved with the FR-4 based low profile material using the PIN diodes. Performance is compared for the simple patch antenna, radome based patch antenna without metamaterial elements and differently shaped metamaterial elements. The presented design provides a minimum reflectance response of −52.20 dB for the reconfigurable circular-shaped metamaterial ring loaded patch antenna. The maximum bandwidth of 5160 MHz is achieved for the circular-shaped metamaterial ring loaded patch antenna. The maximum gain of 2.93 dB is achieved in the radome based patch antenna without metamaterial elements. Maximum tunability of 80 MHz is achieved. The maximum normalized directivity of 110° is achieved with the Square shaped metamaterial ring loaded patch antenna. Simulated results compared with the measured results for the confirmation.The presented design opens new applications in satellite communication, surveillance, wifi devices and manymore. The performance of the presented design also compared with the earlier published work. [ABSTRACT FROM AUTHOR]

This article demonstrated a compact reconfigurable microstrip antenna with a multi-band configuration. It resonates for three different frequency configurations, including the single and dual bands. The primary rectangular patch antenna resonates for WLAN (5.2 GHz center frequency) band. The reconfigurable electromagnetic bandgap (EBG) and parasitic patches near the feed line produce 4 and 6.33 GHz resonance. The defected ground structure is integrated with a PIN diode to make reconfigurable EBG, and it resonated at C band (4 GHz). The PIN diode switching configuration embedded with EBG and one square patch creates dual-band characteristics in wireless local-area network (WLAN) and International Telecommunication Union (ITU) bands. Other PIN diodes switching configurations with primary antenna and two other patches work for C and WLAN bands. The proposed antenna resonated at 4, 5.2, and 6.33 GHz frequencies with different switching configurations of the PIN diode. The simulated results of this novel antenna configuration verified with measured consequences for antenna parameters like reflection coefficient and radiation characteristics are also presented. [ABSTRACT FROM AUTHOR]

In this article, a microstrip antenna having circular polarization switching capability is presented. This antenna consists of a circular-shaped radiating patch with a single co-axial probe feed line. The polarization reconfigurability is achieved by introducing four symmetrical U-shaped slots and silicon PIN diodes on the radiating patch. A prototype of the design is fabricated on an FR-4 substrate with overall dimension of 70 × 70 × 1.6 mm to verify the performances. The measured results of the antenna exhibit an impedance bandwidth (S11 < −10 dB) of 5% in the frequency range of 2.37–2.49 GHz. The maximum gain of the antenna is found to be 2.99 dBic at 2.43 GHz. The antenna shows stable radiation performances at 2.4 GHz with 4.1% of 3-dB axial ratio bandwidth, and more than 105° of 3-dB axial ratio beamwidth for both right-hand circular polarization and left -hand circular polarization which make it suitable for ISM band Smart city applications. [ABSTRACT FROM AUTHOR]

This article represented a heart shape reconfigurable monopole antenna with polarization diversity. The proposed antenna is fed by a 50 O microstrip feed line that is printed on a flexible FR-4 (er=4.4) substrate. The antenna comprises a ring-slot, a cross slot and four positive-intrinsic-negative (PIN) diodes that are soldered on ring slot. Four PIN diodes act as a switch and by controlling these PIN diodes effective current direction is changed hence four various states of polarization are achieved. Four states of polarization such as horizontal linear polarization (H-LP), vertical linear polarization (V-LP), right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP) can be switched easily with the help of these PIN diodes and achieved an efficiency of more than 90%. Proposed antenna shows voltage standing wave ratio (VSWR)<2 at all working frequency and -10 dB reflection coefficients (RC) bandwidths (BW) (i.e., S11=-10 dB) about 32.86% for linear polarization (LP) states while RHCP and LHCP states possess BW of about 31.61% and 31.67% respectively. It also shows axial ratio (AR) BW of 3.41% and 2.44% for RHCP and LHCP, respectively. Besides, the antenna has a well-suited omnidirectional pattern with a positive gain of all working frequency of interest where crosspolarization level is much lower than that of antenna gain. [ABSTRACT FROM AUTHOR]

- In this research paper a new holistic approach of the reconfigurable microstrip patch antenna is presented. The proposed design is applicable for ultra-wide with multiple frequency band for wireless applications. The stated design contains a circular patch with rectangular and elliptical slots cut out in a specific way to get presented results. The antenna is fabricated with FR4 substrate with an inset line feeding to the patch. Frequency reconfigurability is achieved through two pin diodes is connected between the interconnected elliptical slots. The presented approach of designing reconfigurable antenna with the use of elliptical slots and switching reconfigurablitity gives improved performance with the previously compared work in terms of multiple band of operation with improved performance parameters, minimum complexity and size. The simulated antenna design resonates at multiple frequencies before switching at 5.9 GHz, 12.7 GHz, 15.4 GHz, 24.9 GHz, and measured result at 6.9 GHz, 12.9 GHz, 15.3 GHz, 24.9 GHz and after switching the antenna reconfigured and resonated at 6.3 GHz, 8.7 GHz, 16.7 GHz, 28.9 GHz with measured result at 6.3 GHz, 16.8 GHz, 28.9 GHz has been obtained. The simulated and measured results are validated with minor deviation. [ABSTRACT FROM AUTHOR]

Summary: The proposed work represents a simple and effective approach to achieve frequency tunability. The tunability is attained by the switching mechanism of the two PIN diodes. The biasing issue is reduced due to the usage of two PIN diodes. Simulation is carried by a high‐frequency structure simulator tool and compared with the fabricated structure for the authentication. Antenna fabrication is performed by low‐profile material FR‐4. Three modes were analyzed and compared in terms of resonating frequency, reflectance response, gain, bandwidth, and electric field based upon switching of PIN diodes. The proposed antenna structure provides a multiband response with the four frequency tunable bands along with maximum frequency tunability of 700 MHz and a minimum reflectance response of −28.22 dB. The proposed structure opens a new door of applications like satellite communication, military, and a sensor for the S, C, X, and Ku bands. The presented design was also compared with the previously published papers to identify the improvement. [ABSTRACT FROM AUTHOR]

The major focus of the paper is on frequency reconfigurable antenna loaded with slots and slit for future wireless applications. The proposed microstrip antenna with slot, slits and defected ground structure loaded with PIN diode provides a compact and versatile solution with acceptable results for S11< – 10 dB, VSWR ~ 1, and Bandwidth 17.07%. A multi-band frequency operation is observed for 3.76 GHz, 4.26 GHz, 8.06 GHz, 10 GHz, 11.5 GHz and 12 GHz frequencies. The results demonstrate that the antenna bandwidth is a combination of narrowband and broadband, thereby making the antenna a suitable candidate for cognitive radio application for both functionalities i.e. sensing and communicating. The bandwidth observations range from 2.6%, 7.98%, 4.7%,11.3%, 8.78%, 17.073%, i.e. we can say the bandwidth is configurable. The designed antenna is proposed for applications like Cognitive radio, UWB applications, Microwave communication (S, C and X). [ABSTRACT FROM AUTHOR]

In this communication, a pattern-reconfigurable filtering patch antenna is presented which consists of a driven patch, a stacked patch, an embedded filtering feeding line, and two vertical switchable elements with gaps from the suspended patches. Compared with the conventional stacked patch antenna, the proposed antenna does not increase the volume. A novel filtering feeding network is designed which consists of a hairpin-shaped resonator and a half-wavelength coupled microstrip line. It is used to generate the radiation nulls near the lower and higher passband edges. A U-shaped slot is etched on the driven patch to generate another radiation null. Three radiation nulls are excited to realize filtering performance. Meanwhile, the radiation beam of the proposed antenna can be reconfigured by switching the function of switchable elements between a director and a reflector using p-i-n diodes. Good radiation pattern reconfigurability, filtering, and wideband performance can be achieved simultaneously. The simulated and measured results show that the radiation beam can be switched to the directions of −33°, 33°, and 0°. The proposed antenna can maintain a wide operating bandwidth of 2.22–2.84 GHz (25%), out-of-band suppression of over 14 dB, and flat in-band gain of about 8 dBi in different states. [ABSTRACT FROM AUTHOR]

A compact flexible multi-frequency antenna for smart portable and flexible devices is presented. The antenna consists of a coplanar waveguide-fed slotted circular patch connected to a rectangular secondary resonator (stub). A thin low-loss substrate is used for flexibility, and a rectangular stub in the feedline is deployed to attain wide operational bandwidth. A rectangular slot is etched in the middle of the circular patch, and a p-i-n diode is placed at its center. The frequency reconfigurability is achieved through switching the diode that distributes the current by changing the antenna's electrical length. For the ON state, the antenna operates in the UWB region for −10 dB impedance bandwidth from 2.76 to 8.21 GHz. For the OFF state of the diode, the antenna operates at the ISM band (2.45/5.8 GHz), WLAN band (5.2 GHz), and lower X-band (8 GHz) with a minimum gain of 2.49 dBi and a maximum gain of 5.8 dBi at the 8 GHz band. Moreover, the antenna retains its performance in various bending conditions. The proposed antenna is suitable for modern miniaturized wireless electronic devices such as wearables, health monitoring sensors, mobile Internet devices, and laptops that operate at multiple frequency bands. [ABSTRACT FROM AUTHOR]

A method of designing beam-steerable patch antennas with wide stopband suppression is proposed in this article. The wide stopband suppression characteristic is realized by designing suitable parallel coupled lines and open-circuited stubs. The beam steering characteristic is achieved by using a driven patch and two pairs of metal walls vertically placed on both sides of the driven antenna. By controlling the different states of the switching PIN diodes loaded between metal walls, the stable beam steering characteristic can be obtained over the entire operating bandwidth. An experimental antenna is designed and manufactured to validate the approach. The beam steering angles of the simulation and measurement results are ±30°. Moreover, in the three proposed operating states, the out-of-band suppression from 2.6 GHz to 10 GHz is more than 16 dB. The proposed antenna can achieve the characteristic of both wide stopband suppression and beam steering. In addition, the proposed antenna is able to maintain good impedance characteristics during beam steering and maintain stable beam over the entire operating bandwidth. [ABSTRACT FROM AUTHOR]

This work presents a novel proposal for a dual wideband circularly polarized (CP) reconfigurable antenna for wideband wireless communication applications. The circularly polarized characteristic is achieved by introducing a gap in the annular ring, which leads to the generation of traveling waves in circular patterns. The concentric annular ring patch is fed using a tapered 50 Ω microstrip line. Dual wideband characteristics are obtained by incorporating concentric annular rings and additional DGS (defective ground structure) to achieve wideband characteristics. By employing PIN diodes, the proposed approach facilitates reconfiguration, allowing for both left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP) in either single or dual wideband operations. The CP antenna exhibits an impressive measured axial ratio bandwidth (ARBW) of 35 % (3438–4900 MHz) and 18.75 % (5154–6252 MHz). The measured return loss bandwidths of the proposed antenna are 18.40 % (3990–4799 MHz) and 35.17 % (5161–7364 MHz). The antenna, fabricated using FR4, is compact in size, measuring 0.56 λ o *0.56 λ o *0.01 λ o , and has a peak gain of 6.33 dBic. The simulated outcomes and hardware measurement findings agreed well. [ABSTRACT FROM AUTHOR]

In this communication, a low-cost, single-pole double-throw (SPDT) filtering radio frequency (RF) switch based on coupled resonators is proposed and utilized in a novel pattern reconfigurable antenna design. The proposed filtering switch employs two second-order quarter-wavelength microstrip resonant structures which can be controlled by p-i-n diodes, respectively. Compared with traditional switches based on p-i-n diode, this filtering switch can not only improve the RF response but also suppress the high-order harmonic, when it is used with an antenna. Then, a low-profile dual-port broadside/conical dual-mode antenna is proposed by embedding a slotted substrate integrated waveguide (SIW) cavity in the middle of a patch antenna. The slotted cavity is to realize the radiation in the broadside whereas the patch is fed by two probes in-phase to realize the conical radiation. Finally, the filtering switch and the dual-mode antenna are combined to realize the pattern reconfigurable antenna. By controlling the states of the p-i-n diodes, broadside and conical radiation patterns can be easily switched. The concept of switch-based pattern reconfigurable antenna is prototyped and experimentally verified. Measured results agree with the simulations, demonstrating a promising solution for pattern reconfigurable antenna designs. [ABSTRACT FROM AUTHOR]

Summary: In this paper, a compact (15.5 × 32 mm2) reconfigurable microstrip antenna with hexa‐band operation for radio frequency (RF) energy harvesting applications is presented. Three PIN diodes (D3, D2, and D1) for switching action and internet of things (IoT) controlled unit for controlling the resonating frequency of the proposed antenna are used. The antenna resonates at 2.1 and 3.4 GHz (010 state), 3.3 GHz (100 state), 3.2 GHz (101 state), 3 GHz (110 state), and 2.8 GHz (111 state). The proposed antenna exhibits −10 dB simulated and measured impedance bandwidth of 150, 400, 480, 570, 370, and 400 MHz and 120, 410, 400, 470, 320, and 356 MHz in states‐010, 100, 101, 110, and 111, respectively. A maximum peak gain of 3.3 dBi and maximum bandwidth of 570 MHz at 3.2 GHz (101 state) is observed. The proposed antenna is further tested for harvested power, and maximum harvested voltage of 3.9 V, maximum harvested power of 3.013 mW, and 55.07% power conversion efficiency at 20‐dBm power source are recorded. The simulated results have been validated with experimental results. [ABSTRACT FROM AUTHOR]

Reconfigurable antennas have received much attention in RF energy harvesting models owing to their selectivity for operating frequency and polarization. The characteristic of having frequency selectivity and polarization selectivity can be termed as frequency diversity and polarization diversity, respectively. This paper investigates a rectenna device with a new proposed topology in order to eliminate coupling between input and output lines and increase the rectification efficiency with the use of single feed hybrid reconfigurable antenna, switch between 28GHz and 38GHz frequency. Moreover, it is designed to charge a rechargeable battery of 1watt(W). The Reconfiguration mechanism is realized by electronically controlling different states of Switches. PIN Diode (as RLC Equivalent circuit) is used as a switch for ON/OFF states. This antenna mainly comprises rectangular shaped patches (28GHz and 38GHz) with Triango-Truncated edge at the corners. Eighteen PIN Diodes are placed symmetrically throughout the antenna presenting as, S1 & S2 for frequency reconfiguration, S3 to S6 & S7 to S10 connects Triango Truncated edge at the corners for polarization reconfiguration, and for radiation pattern reconfiguration at S11 to S14 & S15 to S18 has been used. The proposed antenna model is capable of simultaneously changing, the radiation patterns as clock and anti-clockwise directions at ±90-degree shift in E and H planes, circularly polarized (CP) states among, Linear Polarization (LP), Right Hand Circularly Polarization (RHCP), and Left Hand Circularly Polarization (LHCP). The current design describes using single antenna for energy harvesting and 5G mobile communication application. This would lead to higher output currents, leading to the ability to efficiently charge a wide variety of batteries. A fully functional prototype has been designed, fabricated and its compound reconfiguration characteristics have been validated for simulated and measured results. For validation of results, the experimental results and the simulation results from the proposed mathematical model were made into comparison, and excellent correlation between the measured and simulated results was obtained. [ABSTRACT FROM AUTHOR]

A pattern reconfigurable microstrip patch antenna with two parallel parasitic patches placed close to both sides of a rectangular driven patch is investigated and presented in this article. Four switchable shorting posts are used to enable the parasitic elements to act either as a reector or director for beam reconfiguration, based on the operating state of four associated PIN diode switches. To avoid large change in the dimension of both parasitic patch and ground plane, and minimize its effect on beam steerability and return loss, two PIN diodes are placed on the top face and the other two on the slots etched on the ground plane. Radiation pattern of the proposed antenna can be reconfigured into four distinct directions in the H-plane with radiation maximum at +40°, 0°, -40°, and ±45°. With overall compact dimension of (35 × 55)mm2 and acceptable return loss for all reconfigurable modes around 6.2 GHz frequency, the proposed antenna is a potential candidate for Wi-Fi 6E application. The measured peak gain varies between 3.9 dBi and 5.2 dBi with an average of 4.6 dBi for all beam tilt angles. Consistency between the simulated and experimental results validates the design theory and its promising application. [ABSTRACT FROM AUTHOR]

In this paper, a new compact design of frequency reconfigurable slot antenna is presented. The proposed radiating patch consists of two symmetrical D shape slots and incorporates four PIN diodes with two stubs which cover a small dimension area of 8.6 × 6.0 × 1.6 mm3. The ground plane is modified by etching two parallel rectangular slots to enhance the bandwidth and design parameter of the antenna. RF pin diodes are used as a switching mode in the slotted D section of the patch which affects the electrical length of the slot antenna, therefore switchable frequency response is obtained. The antenna produces four dual-band states and twelve triple-band states among the sixteen states of diode configuration. The designed antenna resonates at six different resonating frequencies such as 17.4 GHz, 17.5 GHz, 18.9 GHz, 19.0 GHz, 24.9 GHz, and 25 GHz and covers the wide range of frequency from 17.2 to 25.5 GHz which makes it applicable to function at the Ku and K band applications. Simulation of an antenna is done by Ansys HFSS 17.0 software. The results of the simulation show that the antenna has achieved a stable radiation pattern with an appreciable gain of 10 dB, peak directivity 4.26 dBi, peak gain 5.66 dBi, and a maximum bandwidth of 1 GHz with 98% radiation efficiency at these operating frequency bands. [ABSTRACT FROM AUTHOR]

A conformal antenna with electronically tuning capability of its radiation pattern between broadside and monopole-like patterns is proposed. The antenna is based on a proximity-fed circular patch, loaded with a ring patch and four rectangular slots. The design is planar without any use of rigid shorting posts or a complex feeding network. The reconfigurability is achieved by activating and deactivating the slots using p-i-n diodes to switch between TM02 (monopole-like mode) and perturbed TM02 distributions (broadside mode) of the antenna. For conformability, the antenna is fabricated using a highly flexible PDMS-conductive fabric composite. All the antenna parts, including the RF switches, wires, and dc biasing circuit, are fully encapsulated by PDMS to provide resilience against deformation and harsh environment. Investigations on the RF performance and mechanical stability of the antenna were conducted. Under various bendings, it was demonstrated that all the antenna components, including those for electronic switching, remained intact and in working order even under the radius bending of 40 mm, thus maintaining good pattern reconfigurability and overall performance. When bent, the measured results at 5.2 GHz show a stable radiation performance relative to those of the flat case (i.e., the maximum gain of 2.9 dBi and the efficiency of 64% in the broadside mode, corresponding to 1.75 dBi and 52% in the monopole-like mode). To the best of our knowledge, all these features have never been demonstrated in previously published pattern reconfigurable antennas. [ABSTRACT FROM AUTHOR]

In this paper, a microstrip single feed circular radiating patch loaded with two parasitic stubs to achieve diversity for antenna polarization is presented. The primary antenna is a circular metallic patch with a rectangular slotted Defected Ground Structure (DGS) and it resonated at 5.5 GHz for Linear Polarization (LP). To achieve Left and Right Hand Circular Polarization (LHCP and RHCP) two-quarter wavelength metallic stubs are attached with a radiating patch through two PIN diodes. The antenna reconfigures its polarization states between LP, LHCP, and RHCP by diodes switching configurations. The proposed antenna is printed on a 0.8 mm thick RT/Duroid 5880 substrate and it provided satisfactory agreement between measured and simulated results. It has an impedance bandwidth of 5.23–5.75 GHz (9.45%) for S11 less than −10 dB and Axial Ratio Bandwidth (ARBW) for 3 dB is approximately 5.4%. [ABSTRACT FROM AUTHOR]

In this article, we present a low-cost microstrip phased-array antenna, which is composed of electronically reconfigurable elements. The p-i-n diodes’ integrated elements have various functions, such as tunable polarization characteristics and adjustable radiation phases. The high sidelobe level (SLL) due to the 2-bit phase shifter can be reduced by a randomly rotated (RR) array element. It is shown that the array can realize electronic beam-steering capabilities and keep −10 to −14 dB sidelobes without tapering. To verify the above theory, an eight-element linear array prototype working at 3 GHz was designed, fabricated, and tested. Numerical simulations and experimental results show that, by controlling the “ON” and “OFF” states of p-i-n diodes, the radiation beam can be controlled to steer in a circular polarization (CP) mode, wherein the scanning angle is up to ±45°. Furthermore, the principle of suppressing the vector scattering field by the opposite phasing cancellation method can achieve in-band radar cross section (RCS) reduction. Simulation results show that approximately 15 dB in-band RCS reduction can be realized for both bistatic and monostatic RCS reduction with an 8 × 8 array. [ABSTRACT FROM AUTHOR]

A frequency reconfigurable microstrip patch antenna with two asymmetric L-slots is proposed in this article. Two RF pin diodes inserted on the asymmetric L-slots are used to switch the operating frequency over the C band. Design and optimization of different physical parameters of the antenna viz. slot dimensions, feed location, notch size, and pin diode positions are carried out using High Frequency Structure Simulator Version 13.0. The design is implemented on an FR4 substrate (εr = 4.4) of dimension (35 × 40 × 1.6)mm³. DC bias circuitry for RF PIN diode activation is also integrated with the antenna. Switching combinations of two PIN diodes offer four reconfiguration modes of operation at 4.75, 5.05, 5.11, and 5.18GHz. In all the states, the -10 dB bandwidth shows minimal changes with average variations of 15.8% with respect to the state when both PIN diodes are OFF. The gains of the antenna for different modes of operation are found almost stable with an average of 6.64 dBi. [ABSTRACT FROM AUTHOR]

This work discusses the effect of reconfigurability on a Sierpinski-carpet fractal microstrip patch antenna. The implementation of reconfigurability is achieved by modeling a PIN diode as a lumped RC element on HFSS (High Frequency Structure Simulator) simulation tool. The proposed antenna design is also fabricated and tested. It is highly miniaturized having a dimension of 9:5mm x 7:4mm and a significantly high impedance bandwidth which is desirable for most wireless communication applications. The resultant Fractal Reconfigurable Antenna (FRA) exhibits good performance parameters having frequency reconfigurability rendering it useful for Ku/K/Ka band applications. [ABSTRACT FROM AUTHOR]

In this paper, a simple 2 × 2 polarization reconfigurable planar microstrip array antenna is presented. It is based on electrical switching technology using PIN diodes. Each element of the array is excited with the aid of the corporate feed technique. Each element of the proposed structure consists of a corner truncated square patch connected to parasitic triangular conductors by means of PIN diodes. The array element is configured to facilitate linear polarization (LP), right-hand circular polarization (RHCP) or left-hand circular polarization (LHCP) by means of 4 independently biased PIN diodes. The proposed antenna is designed and simulated using electromagnetic simulation software CST Microwave Studio. In order to experimentally validate the design, a prototype is fabricated on a 1.6 mm thick RT Duroid substrate of relative permittivity ϵr = 2.2. The performance of the antenna is validated experimentally using 16 PIN diodes. The simulation and measured results for all the polarization states of the array antenna are found to be in good agreement. The measured results have established the polarization reconfigurable ability of the antenna for 5.7–6.0 GHz operating band. The proposed antenna is suitable for C-band point-to-point communication applications. [ABSTRACT FROM AUTHOR]

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A Ka-band microstrip antenna based on PIN diodes with accurate extraction of equivalent circuit parameters for pattern reconfigurability is proposed in this work. With the increase in operation frequency, the parasitic effect introduced by PIN diodes has tremendous influence on the performance of reconfigurable antennas; hence, the conventional equivalent circuit parameters of the PIN diodes are not applicable for higher-frequency applications, such as millimeter-wave circuits and antennas. Therefore, accurate equivalent circuit models of the conventional PIN diodes are essential in the millimeter-wave reconfigurable antenna design. Based on the combination of simulation and experimental results, accurate equivalent circuit model parameters for the millimeter-wave range of the PIN diode are extracted, with a pattern-reconfigurable antenna being developed afterwards. The proposed antenna consists of two PIN diodes, two interdigital capacitors, an L-shaped slot, and their bias networks. Particularly, the interdigital capacitors are utilized to isolate direct current (DC) from radio frequency circuits, which is able to improve the economic efficiency of the antenna notably as compared with conventional chip capacitors in the Ka-band. By combining a suitable arrangement of the diodes' location and the DC bias networks, the main beam direction of the proposed antenna can be switched between −60° and 60°. To demonstrate the proposed idea, a prototype antenna is fabricated and measured. The measured results agree with the simulation quite well, with a good performance around 30 GHz and a gain greater than 5 dBi for both modes being achieved. [ABSTRACT FROM AUTHOR]