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A simple decoupling method between two closely-located dual-polarized slot antennas is proposed in this communication. Based on substrate integrated waveguide (SIW), the dual-polarized antenna is realized using cross-shaped slot and U-shaped feed line, and two identical elements are closely located in edge-to-edge space of only 0.031λ0 to form the multiple-input-multiple-output (MIMO) array, where λ0 is the free-space wavelength at the center operating frequency. Wideband characteristics, high dual-polarized isolation, and low envelope correlation coefficient (ECC) are realized by introducing a superstrate with gradient relative permittivity (GRP) above the array. The GRP is obtained using drilling hole arrays on low-cost FR-4 materials. To validate the proposed design, the antenna array is fabricated and measured. The measured result shows that 13 dB and 16 dB isolation enhancements are provided for two orthogonally polarized fields, simultaneously. Moreover, the measured operating bandwidth is from 8 GHz to 10.35 GHz (about 25.6%, the isolation is more than 20 dB), and the ECC between two antennas is less than -52 dB for E1-pol and -62.4 dB for E2-pol over entire operating band. The proposed method has the potential to be used in MIMO wireless systems.

In this paper, a low sidelobe-level (SLL) circularly-polarized (CP) leaky-wave antenna with A-shaped elements is proposed based on substrate integrated image guide (SIIG). The A-shaped CP radiating element consists of a horizontal LP structure and a vertical LP structure. The horizontal LP wave and the vertical LP wave can be excited by a pair of inclined transversal metal strip patches and a longitudinal metal strip patch respectively. Their phases are orthogonal and amplitudes can be controlled to be equal by adjusting the tilted angle of the horizontal LP structure and the length of the vertical LP structure. Moreover, the longitudinal metal strip patch is modified to the V-shaped strip patch, which can realize the field cancellation, thereby achieving the boresight radiation for such a leaky-wave antenna. Furthermore, a low SLL is realized by controlling the aperture-field distribution to obtain the desired amplitude distribution and the relatively small axial ratio (AR). In addition, because of the short waveguide wavelength of the SIIG, this feed line can be used to achieve the small interelement spacing and element size, thereby realizing the short length of the array. The measured peak gain of this antenna is 12.3 dBi and the SLL is 19.1 dB.

The microstrip antenna mainly consists of four modules. They are ground plane, dielectric substrate, feed line and radiating patch. Most of time, the patch, feed line and ground plane use copper material whereas the substrate will take different dielectric materials. Hence, the antenna substrate material plays a major role on antenna performance characteristics. This paper presents different types of antenna substrate materials available and also describes the effect of FR4 substrate material on a compact Luna shaped high gain UWB antenna in the frequencies starting from 3.1 GHz to 10.6 GHz. So, this design is produced on the FR4 substrate of size 20 × 18 × 1.6 mm3. It results in S11 ≤ -10 dB from 3.09 GHz to 11.02 GHz. It observes highest radiation efficiency as 98% at 8.6 GHz and maximum peak gain as 5.68dBi at 9.7 GHz. The study of fractional grounds with different types of slots is also shown. The simulation software used is ANSYS HFSS. The simulated and measured return loss is compared.

A compact horizontally polarized omnidirectional cylindrical dielectric resonator antenna (DRA) excited in the TE $_{011+\delta }$ mode is presented. It deploys a planar feed which comprises a cross-shaped feed line, four coupled strips, and four curved arms with end-shorted stubs. The TE $_{011+\delta }$ mode of the DRA is excited by the curved arms. Its intrinsically narrow impedance bandwidth is enhanced by using the coupled strips, and the cross-polar field is suppressed by the end-shorted stubs. The antenna has a measured −10 dB impedance bandwidth of 18.1%, which is much wider than the conventional bandwidths of 4.5%–7.4%. Its cross-polar level is lower than the co-polar level by 15 dB. This basic DRA is used to design the first polarization reconfigurable omnidirectional DRA with diodes. By controlling the states of the diodes, the DRA can be switched between TE $_{011+\delta }$ and TM $_{01\delta }$ modes to obtain horizontal and vertical polarizations, respectively. To verify the idea, a prototype was fabricated and tested. Reasonable agreement between the measured and simulated results is obtained. The measured impedance bandwidths of the TE $_{011+\delta }$ and TM $_{01\delta }$ modes are 16.8% (2.18–2.58 GHz) and 16.0% (2.25–2.64 GHz), respectively. The antenna has stable omnidirectional radiation patterns in both states

In this paper, a quad band-notched ultra-wideband monopole antenna design is proposed. The quad band-notch design is achieved by etching a pair of π-shaped slots on the radiating patch and by a pair of EBG cells coupled on both sides of the feed line. The antenna with this arrangement occupies a 28 × 30 mm2 surface area, producing notch frequencies at 3.5 GHz, 4.2 GHz, 5.7 GHz, and 9.1 GHz with an impedance bandwidth of 3–11. 4 GHz for VSWR

In this paper, a low profile substrate integrated waveguide (SIW) based self-quadplexing antenna with high isolation is demonstrated for multiband wireless applications. Here the SIW based resonator cavity is integrated with an “X”-shaped resonator and formed the four quarter mode cavities having the individual microstrip feed lines. Each quarter mode cavity consists of “V”-shaped slots of different lengths; are in front to feed line and produce the four distinct resonant frequencies at 7.8 GHz, 8.5 GHz, 10.2 GHz, and 10.6 GHz, respectively. The working principle depends upon the perturbation of higher-order modes in a particular quarter mode cavity. The minimum intrinsic isolation of below than −26dB is attained between any of the two input ports by adequately modifying the antenna dimensions. Hence, a single antenna consists of four individual signals without interfering with each other, which determines the self-quadplexing property of the antenna. The proposed antenna is realized for maximum efficiency and minimum value of frequency ratio. The measured gain of the proposed antenna is 4.5 dBi, 5.28 dBi, 7.1 dBi, and 7.4 dBi at the four resonant frequencies, respectively.

This paper is presents a microstrap patch with a T-shaped rectangular antenna workings; the T-shaped patch operating at 3.6 GHz resonating frequency range for 5G application (from 2.9 to 4.4 GHz) repectively. The overall size of the proposed antenna is 22×24×0.25 mm3; the feeding technique using a 50 Ω feed line to the antenna. The proposed antenna is printed on compact Rogers RT 588 lz substrate having permittivity (ɛr) 2.00, loss tangent (tan δ) 0.0021, with thikness 0.2 mm. The proposed antenna introducesmany advantages like small size, low profile, and simpler structure. The characteristics such as radiation pattern, reflection coefficient, gain, current distribution, and radiation efficiency are respectively presented and discussed, using CST microwave study in simulating and analysing. Introducing a slot with a rectangular T-shaped patch antenna achieved lower frequency with 98.474% radiation efficiency and peak gain of the proposed antenna at 2.52 dB. The fractional bandwidth is 42.81% (2.90 GHz to 4.48 GHz) with a resonant frequency of 3.6 GHz and return loss at 28.76 dB. This frequency band attributessuited 5 G mobile application.

A (1 × 2) filtenna array inspired by an inter-digital-based bandpass filter is presented in this paper for simultaneous radiation and filtration. The feed line of the proposed antenna array resonat...

This article presents two kinds of low-cost antennas for $D$ -band short-distance wireless communication applications. Both the antennas are excited by a substrate integrated waveguide (SIW) feed line based on the printed circuit board (PCB) process. The first type is a stainless-steel-based horn antenna, fabricated by electric-discharging machining (EDM) process and selective laser melting (SLM) 3-D printing, respectively, for reducing cost. To integrate the horn antennas with the SIW feed line, a wideband transition structure from SIW to the rectangular waveguide is designed by suppressing higher order eigenmodes. The experimental data show that the integrated horn antenna can achieve 18.9% (129.5–156.5 GHz) −10 dB impedance bandwidth and a peak gain of 15.46 dBi. The second type of antenna is a single-layer rectangular patch antenna fed by SIW. By locally widening the SIW feed line to generate an equivalent shunt capacitance instead of using complex resonators, a wide impedance bandwidth can be realized. The measured −10 dB impedance bandwidth and the peak gain of the patch antenna are 20.8% (125.3–154.4 GHz) and 7.26 dBi, respectively. The two proposed antennas can provide comparable performance for different application requirements under the premise of a low fabrication cost.

A dual-band horizontally polarized omnidirectional antenna for WiFi applications is proposed in this letter, which consists of a 3-D radiation slot on a metal box and three folded patches inside. The 3-D slot is formed by connecting two trapezoid slots at top and bottom of the box with a rectangle slot at the vertical side. Then, the radiation slot is excited by a folded patch connected to the feed line and produces two resonances at 2.45 and 5.5 GHz. With the help of two parasitic patches beside the excited patch, the higher frequency band is broadened. Measured results show that the antenna has two 10 dB return loss operating bandwidths of 5.32% and 20.56%. Moreover, the measured out-of-roundness for the horizontal radiation pattern is less than 2.4 dB in lower frequency band and that of higher frequency band is less than 5.3 dB. Besides, the antenna maintains a compact size of only 22 mm × 10 mm × 25 mm (0.18 λ 0 × 0.08 λ 0 × 0.20 λ 0, where λ0 is the wavelength of the lowest operating frequency), with the gain about 2 dBi and the cross-polarization ratio greater than 20 dB in the entire band.

A T-stub Square Ring Resonator (SRR) based Ultra-Wide Band (UWB) Band Pass Filter (BPF) is studied and investigated in this paper. The proposed filter is based on coupled feed line connected to the T-stub SRR. Ultra-wideband characteristics can be realized by adjusting the T-stub lengths and coupling the gaps between both sides of waveguides and SRR. The characteristics of the T-stub SRR show that the miniaturized UWB BPF can be operated at THz frequencies. The proposed UWB filter is simulated and analyzed using the Finite Differential Time Domain (FDTD) solver-based Computer Simulation Technology (CST) studio suite. The resonance conditions are explained and the transmission performance of the filter agrees with the simulated and theoretical calculations. The proposed filter is best suitable for Electronic-Plasmonic Integrated Circuits (EPICs).

The coexistence of microwave (MW) and millimeter wave (MMW) technologies is considered as the development tendency of the future 5G wireless communication system. In this paper, a single-port, single-layer, dual-band antenna with large frequency ratio is proposed to support the MW and MMW applications. This antenna mainly consists of a stub-loaded microstrip line in the center, two slot-loaded rectangular patches on the lateral sides, and two thin microstrip lines in-between which connect the former two. The stub-loaded microstrip line works as a series-fed MMW linear array at 26 GHz, and simultaneously it serves as the feed line for the MW patches operating at 4.85 GHz. The connection lines are elaborately designed to isolate the MW patches from the MMW signal, guaranteeing the radiation performance of the antenna at the two bands without requiring complicated filter. For verification, a prototype is fabricated and measured. The measured results show that the antenna has an impedance bandwidth of 3.1% and a peak gain of 8.93 dBi at the 4.85-GHz MW band, while an impedance bandwidth of 19% and a peak gain of 13.57 dBi at the 26-GHz MMW band.

This paper is presented a microstrip antenna with a zig-zag feeder for wireless communication, it has a wideband frequency spectrum (2-14) GHz. The proposed antenna is designed with a zig zag feed line which gave a wideband frequency and acceptable gain (7.448-5.928) dB, this antenna has zig zag slots printed in the ground plane on a lower side of the dielectric substrate, a certain form tuning stub is used to increase the matching between the feeder in the top layer of the substrate and ground plane in the bottom, this stub has an elliptical slot to performance matching input impedance with the feed line. The feeding technique used to feed this antenna is a strip feed line of 50 Ω. Different types of techniques are used to enhance the bandwidth of this antenna to get a wideband suitable for the requirements of the UWB antenna such as adjust the feed point position of the feed line with a tuning stub. All the radiation properties of the presented antenna are tested such as bandwidth, radiation pattern, and, gain.

A compact broadband circularly polarized square‐slot antenna based on an offset‐fed inverted‐L‐shaped microstrip feed line is proposed. A rectangular slot beneath the feed line and an inverted‐L‐shaped grounded strip on the left bottom corner of the wide square slot produce dual‐wideband circular polarization (CP) coverage in a compact size. Meander lines with a square slot loaded at the right bottom corner of the ground plane result in broadband CP through overlapping of the dual‐wideband axial ratio (AR) bandwidths. The magnitude and phase differences between two field components can be controlled effectively with proper tuning of the square slot dimensions (4.5 × 4.5 mm2), which is helpful for broadening AR bandwidth over the C‐band by minimizing AR values (≤3 dB). The overall dimensions of the prototype are only 26 × 26 × 1.6 mm3. The antenna prototype has been validated experimentally. The measured results indicate an impedance bandwidth of 104% (3.56–11.22 GHz) and a 3 dB AR bandwidth of 76% (3.90–8.72 GHz). A peak gain of 3.4–4.42 dBi is achieved within the AR bandwidth. The proposed antenna is suitable for CP applications in the C‐band.

An ultra-wideband (UWB) antenna with quadruple-band-rejection characteristics and a size-miniaturised approach for portable wireless applications is designed and experimentally investigated. The pr...

A miniaturized planar microstrip circularly polarized ultrawideband (UWB) antenna loaded by annular-ring slot is proposed and implemented in the paper. With the annular-ring slot loaded in the radiating patch of the antenna, the side of the radiating patch is connected by the asymmetric inverted L-shaped microstrip. At the same time, a quarter of a circle is cut off from the radiating patch. The above designed structure shows improvements on the operating frequency band and realization of the circular polarization radiation. A tapered microstrip is placed between the feed line and the radiating patch to achieve the slow-changing impedance transformation. The results of simulation and measurement demonstrate that the 3 dB axial ratio (AR) fractional bandwidth of the antenna structure achieves 21.25%. The peak gain within the 3 dB axial ratio bandwidth fluctuates between 3.74 and 4.59 dBi. The antenna shows good impedance matching in the ultrawideband range. With the compact structure of the UWB antenna, it has potential application in various wireless communication devices.

This paper introduces a new design for a highly efficient and more compact size dual frequency wireless power transfer (WPT) system, which can operate at both 0.65 GHz and 1.56 GHz bands. The idea of the structure depends on designing a symmetrical system containing Tx and Rx. Each Tx and Rx has a feed line on the top layer with two stubs; each stub has different dimensions than the other one. The bottom layer contains two C-shaped defected ground structures (DGS). By changing the dimensions of one stub, the frequency resonance corresponds to this stub is changed without any change on the other resonance. The system has a size of 20 × 20 mm2. Further, the system achieves efficiencies of 72 % and 89 % at 0.65 GHz and 1.56 GHz, respectively with a transmission distance of 8 mm. The proposed dual frequency WPT is implemented and verified. Good concurrences among electromagnetic (EM) simulations and the measurements have been attained. The system is suitable for recharging shortrange applications.

A compact multiband cavity-backed substrate integrated waveguide (SIW) and metamaterial antenna with coplanar waveguide (CPW) feed is designed for S and Ku bands thereby providing low and high frequency applications. Designing simultaneous achievement of high gain in S band and Ku band antennas are challenging task, but the proposed antenna overcomes this limitation. The proposed antenna has a ground structure with radiating T-shaped stub opposite to the feed line and a combination of SIW and metamaterial. SIW and complementary square split ring resonator (CSSRR) are used to enhance efficiency, directivity, gain and bandwidth. The proposed antenna structure uses FR-4 epoxy as the substrate material with Ɛr = 4.4 with a dimension of 40 × 40 × 1.6 mm and analyzed using ANSYS HFSS. The designed antenna resonates at three frequencies (i.e.), 4.23, 13.63 and 17.05 GHz with a gain greater than 5 dBi and efficiency greater than 80%. It is suitable for S band (ISM, WLAN, WiMax) and Ku band (radar, satellite communications) applications. The designed antenna is linearly polarized with high gain and efficiency at both the bands.

This study proposes a new design of wide bandwidth microstrip antennas using dual feed line techniques. To obtain the optimal impedance bandwidth (IBW) and Axial Ratio Bandwidth (ARBW), several iterations were performed by controlling the dimensions and length of the dual feed line. From the simulation results, the proposed antenna obtained IBW of 0.4GHz or 17% and ARBW of 0.38GHz or 15% at an operating frequency of 2.5 GHz. The gain of the proposed antenna was 5.73dB with a directional radiation pattern. The dual feedline technique successfully improved IBW up to 254.16% compared with the single feed technique. This study would be useful especially for bandwidth optimization of microstrip antennas.

This paper presents the design, optimization, fabrication, and measurement of the compact high gain microstrip antenna with a split ring resonator and set of inverted-F slots along with a matching stub for sub-6 GHz5G applications. In this investigation, different iterations are visualized by incorporating inverted F slots, a split ring resonator, and a matching stub in the transmission line. The advantages of each incorporated structure are analyzed, and a hybrid antenna consisting of the combination is proposed as a final antenna configuration with the optimum results. The proposed final design attains compactness and multi-band operation. Impedance matching is improved by using the stub matched technique at the feed line. The designed antenna shows the resonances at precisely 2.1 GHz, 3.3 GHz, and 4.1GHz. The proposed antenna is suitable for mobile cellular communication such as the LTE band (2.1 GHz), n78 band (3.3 GHz), and n77 band (4.1 GHz) of 5G bands. The gain retrieved from each band attains more than 5 dB value.

Capability of 3D printing for developing wideband multilayered antenna systems packaged with active RF circuit components remains relatively unexplored. To address this gap, this manuscript demonstrates wideband patch antenna that is integrated with a polarization selection switch. Antenna bandwidth is enhanced with customized substrate thicknesses and stacked patch layers. Switch is integrated with 3D vertical transitions to achieve wide bandwidth, smaller packaging, and low-loss. To enable future antenna array applications, a detailed investigation is also presented to maximize the performance of the microstrip feed lines by adjusting the substrate thickness and deposition process. The antenna consists of 13 dielectric and conductive layers. Specifically, the manuscript demonstrates the lowest attenuation in the literature for a fully printed microstrip line with 0.25 dB/cm measured loss at 18 GHz. The antenna operates with more than 80% radiation efficiency and 45% bandwidth. The polarization switch is embedded within the antenna structure. The antenna retains a high cross-polarization ratio of ~20 dB due to 3D feed line transitions and symmetric location of the switch with respect to the antenna feeds.

The term Reconfigurable antenna plays a significant role in almost all applications where multi tasking and compactness are the key specifications. Reconfigurable antennas can radiate at different frequencies and are well opted for most of the wireless Telecommunication protocol standards. This paper addresses a well dedicated switching mechanism was proposed to switch the antenna radiated power for different frequencies and to support different communication network standards at different frequencies like WLAN 5.2/5.8 GHz, Wi-Fi 5.5 GHz, WiMAX 3.5/5.5 GHz and 3G UMTS at 2.1 GHz. A 14 armed monopole antenna is etched on the top of FR4 dielectric substrate with silt in ground plane and feed line is deigned. This dual slit mechanism will help to achieve reconfiguration, through switching operation between specific frequency bands giving different polarization. Later on the proposed model is simulated using HFSS software.

A travelling-wave-fed slot spiral antenna with wide axial-ratio (AR) bandwidth and beamwidth for GNSS applications is proposed in this paper. The evolution procedure of the proposed antenna can be classified into three steps. Firstly, 12 identical spiral slots are arranged concentrically in a compact area, and AR roundness in low elevation plane is improved by virtue of good rotational symmetry of slot radiators. Secondly, a two-turn travelling-wave feed line is sequentially coupled to the slots, and wideband response of desired magnitude ratio and phase difference of $E_{\theta }$ and $E_{\varphi }$ is obtained by optimizing the number and growth rate of microstrip turns. Thirdly, by supporting the antenna with a modified metallic cavity, the CP radiation performance in low elevation plane is well improved, and thus a widened AR beamwidth is obtained. Finally, the proposed antenna with satisfactory performance is realized in a diameter of $0.56\lambda _{0}$ and height of $0.12\lambda _{0}$ , where $\lambda _{0}$ is the free-space wavelength at center frequency 1.4 GHz. Measured bandwidth of $|S_{11}|$ fully covers the entire GNSS bands, and the 3-dB AR bandwidth ranges from 1.14 to 1.67 GHz (37.7%). Moreover, the 3-dB AR beamwidth exceeds 140° at 1.4 GHz.

This article describes a quad-band frequency tunable antenna for 5G applications that operates in the sub-6 GHz frequency range. On the top side, a stubloaded square patch is printed on an inexpensive glass epoxy substrate, and on the opposite side, a C-shaped slot embedded into the partial ground plane. To achieve frequency reconfigurability with a consistent radiation pattern, the C-shaped slot and matching stub are used. The antenna is electronically frequency tunable by placing two positive intrinsic negative diodes (PIN) in the C-shaped slot and one PIN diode between the stub and feed line. The frequency is tunable between one ultra-wideband (UWB) and three communication bands based on the switching conditions of the PIN diodes. The proposed configuration is small, with a substrate dimension of 25×25×1 mm3. The antenna was fabricated, tested and found measurements result back up the simulation; it can switch between UWB (3.31.0-6.03 GHz) and three communication modes (3.31-4.32, 3.78- 4.98, 4.98-5.96 GHz). The antenna has peak gains of 1.91, 1.86, 2.0 and 2.0 dB, and radiation efficiencies of 80, 78, 83 and 86%, respectively, in the four frequency bands. The developed antenna is ideally suited for multi-functional wireless systems and cognitive radio applications since it covers the frequency bands below 6 GHz and is tunable between wide and narrow bands.

This paper introduces a novel transparent proximity-coupled-fed patch antenna with enhanced impedance bandwidth and good filtering response. The proposed antenna consists of a ground plane, a specific feeding structure and a slotted patch. All the conducting surfaces are realized with metal meshes printed on glass substrates. Optical transparency of the antenna depends on the mesh density. The feed line of a traditional proximity-coupled-fed patch antenna is terminated with a driven stub etched with a half-wavelength U-shaped slot. This modification introduces an additional resonant mode but also a radiating null. By further etching a pair of quarter-wavelength open slots on the radiating patch, another resonant mode accompanied with an extra radiation null is generated. Finally, three resonant modes within the operating band along with two radiation nulls near the two edges of the passband are achieved. The proposed antenna is implemented to demonstrate an impedance bandwidth of 7.6% from 3.41 to 3.68 GHz and a maximum gain of 4.6 dBi.

The high tech industrial revolution in the last fifty years depleted and ruined the planet natural resources. Energy harvesting is the main challenge in the research in green technologies. Compact wideband efficient antennas are crucial for energy harvesting portable sensors and systems. Small antennas have low efficiency. The efficiency of 5G, IoT communication and energy harvesting systems may be improved by using wideband efficient passive and active antennas. The system dynamic range may be improved by connecting amplifiers to the small antenna feed line. Ultra-wideband portable harvesting systems are presented in this paper. This paper presents new Ultra-Wideband energy harvesting system and antennas in frequencies ranging from 0.15 GHz to 18 GHz. Three wideband antennas cover the frequency range from 0.15 GHz to 18 GHz. A wideband metamaterial antenna with metallic strips covers the frequency range from 0.15 GHz to 0.42 GHz. The antenna bandwidth is around 75% for VSWR better than 2.3:1. A wideband slot antenna covers the frequency range from 0.4 GHz to 6.4 GHz. A wideband fractal notch antenna covers the frequency range from 6 GHz to 18 GHz. Printed passive and active notch and slot antennas are compact, low cost and have low volume. The active antennas may be employed in energy harvesting portable systems. The antennas and the harvesting system components may be assembled on the same, printed board. The printed notch and slot antennas bandwidth are from 75% to 100% for VSWR better than 3:1. The slot and notch antenna gain is around 3 dBi with efficiency higher than 90%. The antennas electrical parameters were computed in free space and near the human body. There is a good agreement between computed and measured results.

To meet the anti-interference and multi-function requirements of the antenna, a compact 8-states frequency reconfigurable ultra-wideband (UWB) monopole antenna is proposed. The antenna consists of a coplanar waveguide structure (CPW), defected ground structure (DGS), rectangular radiation patch, and stepped feed line. Band rejections at the C band, WLAN, and X band are generated by two C-slots and inverted U-slot, respectively. Three PIN diodes are connected across the C-slots and inverted U-slot. By controlling the on/off state of PIN diodes to realize notch reconfiguration. The antenna size is only 22 mm $\times 13$ mm $\times0.8$ mm. The measured results show that the antenna can work in 8 states. The impedance bandwidth of UWB mode is 2.82-13.25 GHz, the relative bandwidth is 129.8%. The notch band is 3.19-4.58 GHz, 5.26-6.21 GHz, and 7.87-8.73 GHz, respectively. The antenna has stable gain, good omnidirectional radiation performance, and can switch freely between UWB mode and each notch band mode.

Purpose The suggested antenna has a switched mechanism among the successive elements of the radiating patch. The purpose of this paper is to develop high gain and less interference at higher frequencies. Design/methodology/approach The design geometry of the suggested high gain switched beam Yagi-Uda antennas. The constructed antenna has been developed with Rogers Substrate, relative permittivity (εr) of 4.4, tangent of loss 0.0009 and with height of 1.6 mm. The proposed antenna has an input impedance of 50, and it is connected to input feed line with 2 mm. Findings In forthcoming life, the antennas play key role in all the wireless devices, because these devices perform with high gain and high efficacy. Originality/value The pivotal principle of this paper is to accomplish the gain as high, high directivity and interference is low at higher frequencies. Therefore, it is more applicable to 5G mobile communications and millimeter wave communications.

A compact wideband coplanar waveguide (CPW) excited slot antenna with dual-circular polarization (DCP) is presented and fabricated in this paper. Two inverted-L-shaped patches are implanted in a square slot to achieve wideband DCP characteristic. The feed line is terminated on an inverted-L-shaped patch. Moreover, two rectangular slots are added on the corners of the antenna to improve the bandwidth of axial ratio (AR) and the voltage standing wave ratio (VSWR). The simulated results show that the designed antenna can generate a good impedance bandwidth of 70.4% and a 3-dB AR bandwidth of 48.6%, respectively. This antenna possesses the qualities of small size, simple structure, and good dual-circular polarization.

A novel miniaturized printed monopole antenna for ultra-wideband (UWB) bidirectional brain machine interface (Bi-BMI) applications, based on defected feed line and parasitic structures, is designed...

A planar 2 × 2 filtering patch antenna array with high selectivity and wide stopband is investigated for marine communications. The 2 × 2 patch array is composed of a driven patch and four identical parasitic patches placed nearby. A forked-microstrip-line-coupled rectangular slot is used to excite the driven patch, while the neighboring parasitic patches are capacitively coupled by the driven patch. Owing to the hybrid feeding effect of the forked feed line, a radiation null can be generated at the lower band-edge. Simultaneously, another radiation null can be generated at the upper band-edge owing to the radiation cancellation effect between the driven patch and the parasitic patches. Consequently, no power dividing feeding network is required for the 2 × 2 array, and the quasi-elliptic bandpass filtering response is achieved without utilizing any complex filtering/non-filtering circuits. In addition, the proposed filtering array exhibits a wide stopband capable of suppressing the second-harmonic radiation effectively. Based on this 2 × 2 array, a larger 4 × 4 filtering array is further designed by just using a traditional four-way power dividing network. For validation, both of the 2 × 2 and 4 × 4 filtering patch arrays operating at 5.25 GHz are fabricated and tested. The measured results show that the two patch arrays have comparable impedance bandwidths of about 4.4%. The in-band peak gains are given by 11.1 and 15.5 dBi respectively, which are suitable for the long-distance shore-to-ship communications.

A planar rectangular slot antenna with dual-band operation and realized higher peak gain is proposed, designed, and fabricated for sub-6 GHz 5G applications. The antenna possesses a rectangular radiating slot with the inverted stub on its upper edge excited simultaneously by a micro-strip feed line having a double folded T-shaped structure. The fabricated design is of compact size with the radiating portion of 0.3 λ0 × 0.17 λ0 (λ0 represents free-space wavelength) and profile of 0.009 λ0. The measured results show the operating frequency bands of 3.29–3.63 GHz and 4.3–5.2 GHz, with a peak gain of around 7.17 dBi. The higher frequency band is generated by the feed patch and the slot whereas lower resonant frequency band is generated by the stub loaded on the slot. The measured results are in a good agreement with the simulated results. The proposed design is suitable for the International Telecommunications Union sub 6 GHz applications.