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In this article, compact a multiple-input and multiple-output (MIMO) system with flag-shaped radiators and a mountain-shaped ground plane is presented. Isolation is enhanced with the help of a decoupling stub placed between radiators, where two bands are stopped with the help of slits etched into the radiators. The overall size of the proposed antenna is 15 mm ×25 mm ×1.6 mm. The reflection coefficients are less than -10 dB between 3–10.9 GHz, except the bands WiMAX (3.2–3.7 GHz) and WLAN (5–6 GHz); similarly, measured and simulated transmission coefficients are less than -20 dB across the entire band of UWB. The envelope correlation coefficient (ECC) is less than 0.02 and the diversity gain is greater than 9.9 dB. The gain, ECC, radiation pattern, multiplexing efficiency, diversity gain and various other parameters are discussed and evaluated in detail.

In this article, a simple method is developed to design a highly miniaturized tri-band bandpass filter (BPF) utilizing two asymmetric coupled resonators with one step discontinuity and one uniform impedance resonator (UIR) for worldwide interoperability for microwave access (WiMAX) and radio frequency identification (RFID) applications. The first and second passbands located at 3.7 GHz and 6.6 GHz are achieved through two asymmetric coupled step impedance resonators (SIRs), while the third passband, centered at 9 GHz, is achieved using a half-wavelength UIR, respectively. The fundamental frequencies of this BPF are implemented by tuning the physical length ratio (α) and impedance ratio (R) of the asymmetric SIRs. The proposed filter is designed and fabricated with a circuit dimension of 13.69 mm × 25 mm (0.02 λg × 0.03 λg), where λg represents the guided wavelength at the first passband. The experimental and measured results are provided with good matching.

This paper presents a novel technique based on Hybrid Spatial Distance Reduction Algorithm (HSDRA), to compensate the effects of deformity and mutual coupling occurred due to surface change in conformal arrays. This antenna surface deformation shifts the position of null points and loss of the main beam resulting in reduced antenna gain along with substantial undesirable effects on the antenna performance. The proposed algorithm, which cumulatively incorporates the Linearly Constraint Least Square Optimization (LCLSO) and Quadratically Constraint Least Square Optimization (QCLSO) techniques, is formulated to minimize/reduce the absolute distance between the actual (simulated/measured) radiation pattern and the desired radiation pattern while keeping the direction of main beam and nulls position under control. In particular, a 4x4 conformal microstrip phased array from planar surface is deformed to prescribe spherical-shape surface with various radii of curvature, is validated. For the enhancement of Gain of the conformal array antenna, Gain Maximization Algorithm is also proposed, the simulated results of which is compared to the traditional Phase compensation technique and unconstraint least squares optimization. The analytical results for both planar and spherical deformed configurations are first evaluated in MATLAB and then validated through Computer Simulation Technology (CST).

This study proposes a novel reconfigurable antenna for the millimeter-wave frequency spectrum. The proposed hybrid reconfigurable antenna is designed to reconfigure antenna parameters in compliance with wireless application specifications, such as frequency and radiation patterns. PIN Diodes as a switch are used to monitor the reconfiguration features i.e. adjusting the frequency response and radiation pattern of the antenna. For the desired goal, antenna is incorporated with three switches (S1, S2 & S3). The main beam of the antenna is guided by S1 and S2 which connects parasitic stubs H1 and H2 and the frequency is controlled by S3 between 28 and 38 GHz which connects patch P1 with P2. Proposed work is validated for 28 GHz and 38 GHz operational bands. When S3 is active (at ON state), the proposed antenna operates at 28 GHz resonant frequency with a reflection coefficient of − 32.3 dB and when S3 is in-active (at OFF state), it results in 38 GHz resonant frequency with a reflection coefficient of − 42.1 dB. RTDuroid5880 with $$\varepsilon _{{\text{r}}} = 2.33$$ , $$\tan \delta = 0.0009$$ and thickness (h) of $$0.506\,{\text{mm}}$$ and is excited through an inset feed. HFSS software is used for the simulation purpose.

In this paper, a coplanar waveguide-fed ultra-wideband-multiple-input and multiple-output (UWB-MIMO) antenna with a novel stub for isolation has been presented. The dimensions of the proposed antenna are 18 × 22 × 1.6 mm3. The proposed antenna is design on an FR4 substrate and simulated in CST studio. The |S11| of the presented MIMO antenna is less than −10 dB between 2.8 and 13 GHz with an impedance bandwidth of 10.2 GHz. The envelope correlation coefficient (ECC) is less than 0.007 and diversity gain (DG) is greater than 9.97 dB. The proposed UWB-MIMO antenna is analyzed in terms of isolation, reflection coefficient, current distribution, ECC, DG, peak gain, multiplexing efficiency, and radiation pattern.

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.

Inherently UWB (Ultra Wideband) communication systems comes with interference problem with some if the existing narrowband communication systems. These bands are stopped with the help of band-stop filter in order to reduce electromagnetic interference However, the complexity and limitations are increased due to these filters, hence this solution is turned down in those applications where design complications and complexity is of concern. Introducing various slots of specific shapes and exact dimensions however, have solved this issue for the researchers around the world. This paper presents a hexagonal PMA (Printed Monopole Antenna) with triple stop bands. The antenna is used for UWB application. The antenna is stopped the WiMAX (Worldwide Interoperability for Microwave Access), WLAN (Wireless Local Area Network) and ITU (International Telecommunication Union) bands. The antenna dimensions are 30x28x16 mm3. FR4 is used between ground and radiating patch with relative permittivity of 4.4. The VSWR (Voltage Standing Wave Ratio) is less than 2 between 3-11 GHz except WiMAX (3.1-3.7 GHz), WLAN (5.1-5.8 GHz) and the ITU frequency band (7.95-8.4 GHz). The antenna is design in CST software.

This paper presents the results of simulation and experimental investigations on a locally fabricated patch antenna using a high dielectric ceramic (alumina) substrate. The antenna was designed for a centre frequency of 6.32 GHz within C-Band which was excited using micro-strip line feed. The bandwidth of the simulated antenna was achieved as 66.1 MHz with a return loss of 21.7 dB at the centre resonant frequency. The observed resonance frequency at the centre was found to be 6.32 GHz with a return loss of 37.55 dB for the locally fabricated antenna. The -10 dB bandwidth of the fabricated design was determined as 251 MHz. Impedance presented at central frequency was 51.2 ohm that indicates an outstanding impedance-matching between antenna and feed line. The obtained results indicate that the fabricated antenna is suitable for its applications in C-band.

In this article, a new method is developed to design a three-band miniaturized bandpass filter (BPF) that uses two asymmetrically coupled resonators with one step discontinuity and open-circuited uniform impedance resonator (UIR) to achieve Global Interoperability with Microwave Access (WiMAX) and Radio Frequency Identification (RFID) applications. First, a pair of asymmetrical step impedance resonators (ASIR) is used to implement a dual band filter, then a half wavelength uniform impedance resonator is added below to the transmission line to achieve a triple band response. The proposed filter resonates at frequencies of 3.7 GHz, 6.6 GHz, and 9 GHz with the fractional bandwidth of 7.52%, 5.1%, and 4.44%, respectively. By adjusting the physical length ratio (α) and the impedance ratio (R) of the asymmetric SIR, the proposed fundamental frequencies of the triple BPF are obtained. Moreover, the coupling coefficient (Ke) and external quality factor (Qe) are investigated between the resonators and the input/output ports of the transmission line and are calculated using full-wave EM simulator HFSS. In addition, five transmission zeros are introduced near the passbands to increase the filter selectivity. Finally, the proposed filter is designed and fabricated with a size of 13.69 × 25 mm (0.02 λg × 0.03 λg), where λg represents the guiding wavelength in the first passband. The simulated and measured results have a good correspondence, thus confirming the design concept.

In this paper, a half-circular disc PMA (Printed Monopole Antenna) for SWB (Super Wide Band) applications is presented. The dimensions of the substrate is 40x40x1.7mm. The antenna is printed on Rogers RT5880 dielectric material. The antenna VSWR (Voltage Standing Wave Ratio) has less than 2 between 2.7 and 50 GHz. The antenna S11 has less than -10 between 2.7 and 50GHz. The antenna has a maximum gain of 12.4dBi. The BW (Bandwidth) of the proposed antenna is about 47.3 GHz. The antenna covered the WiMAX ((Worldwide Interoperability for Microwave Access), WLAN (Wireless Local Area Network), X band, Ka band, Ku band, 4G band, and the band of 5G (Fifth Generation) at the same time with nice gain and radiation efficiency. The radiator of the proposed antenna designs from a half-circular disc, rectangle, and triangle. The antenna has a partial ground plane. Three slots are etched in the ground plane for better impedance matching, two are circular slots and one is the rectangular slot. The antenna design is simulated in CST microwave studio 2016. The antenna has good radiation efficiency, other parameters such as VSWR S11, gain, and radiation pattern are discussed in detail.

This paper presents a novel combo-reconfigurable architecture for the frequency and radiation patterning of a novel antenna system for future fifth-generation (5G) millimeter-wave mobile communication. The tuning system independently controls the frequency and radiation pattern shifts, without letting them affect each other. The proposed antenna consists of two patches, radiating at 28 GHz and 38 GHz. A negative-channel metal&ndash, oxide&ndash, semiconductor (NMOS) transistor was used as a switch for ON/OFF states. Frequency reconfiguration was controlled by switches SD1 and SD2, while pattern reconfigurability was achieved by SD3&ndash, SD18. The desired resonant frequencies of 28 GHz and 38 GHz were achieved by varying patch dimensions through the ON and OFF states of the SD1 and SD2 switches. Similarly, parasitic stubs on the ground are used to control surface currents, which results in pattern reconfiguration. The results were analyzed for 18 different combinations of the switch states. Adding/removing parasitic stubs and switches changed the beam steering angle (by 45&deg, shift) from 0&deg, to 180&deg, which modified the stub dimensions and changed the beam-width of the main lobe.

With the advancement of world to 5th Generation cellular communication system presently commercial implementation of 5G in USA, UK, Switzerland, South Korea and Spain a space for improvement of radiation characteristics is always there for Antenna to accommodate the high gain demands of 5G. In this paper the design and simulation of compact, millimeter wave antenna array for 5G wireless communication network is proposed operating at 30 GHz and 50 GHz. Ka band from 26GHz to 42 GHz and V band from 40GHz to 75GHz need dual band frequency for its application from a single antenna. A conventional patch antenna with dimension 3×3 mm2 is designed on Rogers RT5880LZ substrate material with thickness of 0.787 mm. Two Rectangular and one circular slot is made in the patch to attain another band at 50 GHz frequency. In this proposed antenna array configuration of 2×1 met the requirement s of improved radiation characteristics. In this proposed antenna array configuration meets the commercial demands such as 75 ohm coax cable and substrate material with thickness of 0.787mm. The realized gain of 10.2 dB & 11.6 dB and return loss value of −12.5 & −14.85 at 30 GHz and 50 GHz respectively is achieved. The bandwidth is 2.093 GHz and 1.764 GHz at 30GHz and 50GHz Respectively. The VSWR value measured from simulation is 1.67 and 1.43 at dual bands frequency which is less than 2. The proposed antenna is fed by corporate feed network technique.

Multiband high gain antennas are the essence of future wireless communication networks. This paper presents a detailed investigation and design of 1×4 linear and 2×2 planar array antennas. Arrays are designed using Rogers RT/duroid5880 (lossy) substrate. Thickness, dielectric constant and tangent loss of the substrate are 0.508 mm, 2.2 and 0.0013 respectively. Both arrays are multiband antennas and have resonance frequencies in K band, Ka band and V band. The maximum and minimum gains of 14.22dB and 9.9dB are achieved at 44.8 GHz and 67.8 GHz using linear array. The highest gain of planar antenna is 12.34dB at 29GHz and lowest gain of 8.5 dB is obtained at 38GHz. Radiation efficiency of both antennas are in the range of 90% at all the resonance frequencies. Results of both arrays show that array with linear setup have better gain than array of planar setup whereas bandwidth and return loss of planar array is better than linear array.

A circularly polarized rectangular dielectric resonator antenna (DRA) has been designed (3.7–4.2 GHz) for WiMAX, satellite, and sub-6 GHz 5G NR band communications. A new T-shaped monopole has been used to excite the rectangular DRA. Using proposed conformal metal strip, the higher-order degenerate modes TE δ 13 x and TE 1 δ 3 y have been excited to achieve circular polarization (CP) with improved gain. Further, the bandwidths enhancement has been achieved by placing a parasitic patch of optimized height and width at a specific distance from T-shaped strip on DRA surface to cover the desired frequency band. A signaficant enhancement of ~ 73% in the impedance-matching bandwidth and ~ 75.5% in axial ratio (AR) bandwidth has been achieved. The | S 11 | ≤ 10 dB over a wide bandwidth of ~ 17.3% has been offered by the antenna. A broad axial ratio bandwidth of ~ 17.2% along with a useful gain of ~ 6.32 dBic has been provided by the antenna. The antenna designing and optimization has been carried out using CST® Microwave Studio. A reasonable agreement between simulated and measured results has been observed.

This paper proposes a compact, semi-circular shaped multiple input multiple output (MIMO) antenna design with high isolation and enhanced bandwidth for ultrawide band (UWB) applications. A decoupling stub is used for high isolation reaching up to &minus, 55 dB over the entire bandwidth. The proposed antenna is used for UWB as well as super wide band (SWB) applications. The overall size of the proposed antenna is 18 &times, 36 &times, 1.6 &nbsp, mm3. The | S 11 | &nbsp, and voltage standing wave ratio (VSWR) of the proposed antenna are less than &minus, 10 dB and 2, respectively, in the range of 3&ndash, 40 GHz. The total impedance bandwidth of the proposed design is 37 GHz. The VSWR, | S 11 | , | S 22 | , | S 21 | , | S 12 | , gain, envelope correlation coefficient (ECC), radiation pattern, and various other characteristic parameters are discussed in detail. The proposed antenna is optimized and simulated in a computer simulation technology (CST) studio, and printed on a FR4 substrate.

This paper presents the implementation of Millimeter wave (MMW) reconfigurable antenna in a real word environment. Wide bandwidth feature of these waves is the next generation 5G networks. Coplanar waveguide (CPW) feeding technique is used to achieve re-configurability, slotted Y-shaped antenna. The proposed antenna model is incorporated by two variable resistors, which helped in varying of resonant frequency around 26–29 GHz to achieve 10 dB return loss. A comparative analysis is observed among Gain, Directivity and Radiation efficiency pattern of variable resistance. Furthermore, CPW fed technique is compared with Grounded coplanar waveguide (GCPW) for better efficiency and S11 in dB. The uses of millimeter wave bands include point to point communication, inter-satellite links and in mine tunnels. The proposed antenna is designed using CST microwave studio.

This paper presents the effect of water on a pair of 1.8GHz on-body diversity monopole antennas mounted on the forearm of a sitting male static volunteer. Application of a water layer to the forearm was seen to both reduce efficiency and increase directivity leading to a slight overall increase in gain. Increased gain was shown to increase antenna correlation thereby reducing diversity gain in the antenna pair.

In the design and synthesis of wearable antennas isolation distance from the body is a critical parameter. This paper deals with the comparison of perturbations caused to the matching of simple linear and circular polarized patch antennas due to the close proximity of a human torso and rectangular box phantom filled with muscle simulating liquid at 1.8GHz. The isolated variable is return loss (S 11 ). Results show that both linear and circularly polarized antennas produce an optimal return loss closer to the surface of a typical phantom than the back of a human volunteer.

This novel paper presents a low profile antenna based on the properties of a non-uniform electromagnetic bandgap (NU-EBG), i.e. a non-uniform high impedance surface (NU-HIS). The structure, referred to as Flexible EBG Inverted-L (FEBGIL) antenna, is an efficient wearable antenna incorporating a planar inverted-L element adjacent to some non-uniformly spaced high impedance elements. While the bandwidth is approximately 10% at 1.85 GHz, the overall electrical size is quite small providing an ideal condition for the antenna to be worn on biceps (upper arms). This design is able to minimize electromagnetic interaction with the body on which it is worn and therefore can reduce Specific Absorption Rate (SAR) and degradation in radiation efficiency.

This paper presents a novel flexible wearable multi-band printed monopole antenna on a neoprene substrate. Bands covered are GSM 900 (890-960 MHz), DCS (1710- 1880 MHz), PCS (1850-1990 MHz), UMTS (1920-2170 MHz) and WLAN 2.4 GHz (2400-2484 MHz) bands. The antenna is optimised for performance on the body.