H-shaped Slot Research Articles

Low profile wide band high gain transmitarray antenna for Ku band applications

A wideband transmissive surface with identical slots on 15 × 15 unit cells proposes in this article. The high gain transmitarray antenna presents using Huygens' principle at 15 GHz. The transmitarray surface consists of trilayer H-shaped slots on the middle of four symmetric slots on the edges of the unit cells. The placed slots induce Huygens’ resonances at three frequencies, 13.5 GHz, 15 GHz and 16.7 GHz which is caused by electric and magnetic surface currents on the transmitarray surface. This makes a wide bandwidth for the antenna performance. 360° phase distribution is obtained by increasing the H-shaped slots legs. Since no dielectric substrate used between layers, the transmission coefficient is near 1 (0 dB) through the whole range. For experimental results, the trilayer artificial metallic surfaces with substrateless conductive slotted unit cells is fabricated. The test results presented the transmitarray antenna peak gain is measured 28.6 dB at operating frequency, 15 GHz. Ultra wide band antenna with 3 dB gain bandwidth of 30% and high aperture efficiency of 42.66%.

Design of circular slots loaded MIMO antenna with DGS at 28 GHz for 5G wireless services

In this paper, a MIMO microstrip patch antenna with four radiating elements is designed and analyzed at 28 GHz. This paper addresses the problem of mutual coupling without adding a decoupling network. The decoupling method increases the complexity and volume of MIMO antennas. The CST Microwave simulator is used to simulate the MIMO antenna. The simulation and measurement results are compared to analyze the antenna's performance. The parameters of the MIMO patch antenna, including return loss, VSWR, gain, beam width, and radiation pattern, are evaluated at a center frequency of 28 GHz. The overall dimensions of the MIMO antenna are 60 × 42 × 1.6 mm3.An H-shaped slot is inserted in the middle of the ground plane to minimize mutual coupling among the radiating elements. The isolation amplitude between radiating elements is observed greater than 35 dB at 28 GHz frequency. A wide impedance bandwidth of 4 GHz (26.5 to 30.5) is achieved, by etching four small arcs into the patch’s corners. In this work, two circular slots are inserted on the radiating element to widen the bandwidth further by adjusting the surface current on each radiating patch. At the center frequency of 28 GHz, the Envelope Correlation Coefficient (ECC) is observed to be 0.0001, with a diversity gain of 10 dB. The antenna has a maximum radiation efficiency of 75% and a peak gain of 7.62 dB. This antenna can be used for 5G wireless services.

Design and Implementation of Novel H-Shaped Self-Diplexing SIW Rectangular Cavity-Backed Antenna with Harmonic Suppression for Terrestrial Communications

A novel and low profile, planar, rectangular cavity-backed self-diplexing substrate integrated waveguide (SIW) antenna with H-shaped slot for dual-band wireless services was designed and demonstrated. The proposed antenna structure radiates from H-shaped slot, which is etched on top of the SIW rectangular cavity, and is excited by two separate 50 Ω microstrip feed lines. The H-shaped slot is a combination of two vertical slots and one horizontal slot; because of that the presented antenna radiates at two distinct frequency bands around 8.95 GHz and 10 GHz, simultaneously. The design methodology results show that the H-shaped slot is significantly more effective than various other slots in the proposed geometry to suppress the unwanted harmonics, attaining good impedance matching and bandwidths and achieving better isolation between these two ports. Hence, the complete design mechanism helped to achieve self-diplexing characteristics. Furthermore, a self-diplexing H-shaped SIW rectangular cavity-backed antenna was fabricated and characterized for the complete demonstration purpose and found good covenants between the simulated one. Measured results show that the presented designed has impedance bandwidths for the lower and upper frequency bands of around 2.0% (8.89–9.03 GHz) and 3.1% (10.01–10.32 GHz), respectively, and obtained maximum measured gain of 5.11 dBi and 5.41 dBi at 8.95 GHz and 10.15 GHz, respectively. The proposed self-diplexing SIW rectangular cavity-backed structure shows that front-to-back ratios (FTBRs) are more than 21 dB, and on the other side, it provides good isolation between the two ports, which is more than 20 dB.

Microwave Power Limiter Having H-Shaped Slot Structure With Enhanced Plasma Discharge by Electrostatic Potential

Microwave Power Limiter Having H-Shaped Slot Structure With Enhanced Plasma Discharge by Electrostatic Potential

Broadband Linear Polarization Converter Based on Slot-Line Loaded Structure for Pre-Determined Notched Band

This brief proposes a broadband linear polarization converter with pre-determined notched band. By loading a H-shaped slot line on the basis of the rectangular resonator, a pair of resonator modes as well as pre-determined polarization conversion zeros can be additionally allocated inside the band, thereby realizing broadband and band-notch characteristics, simultaneously. The multi-mode resonant mechanism to realize broadband and the conversion zero control principle for notched band are analyzed in detail. Finally, a notch-band broadband linear polarization converter is designed and fabricated, and the simulated and measured results are agreed well with each other. As the main advantage, the proposed multi-mode resonant structure realizing the notched band can achieve flexible isolation band design while hardly affecting the broadband filtering characteristics, and is especially suitable for pre-determined spectrum windows of broadband electromagnetic control devices.

Slotted Substrate-Integrated Waveguide Leaky-Wave Antenna with Improved Backward Scanning Bandwidth and Constant Gain in X-band

An H-shaped slotted leaky-wave antenna (LWA) is proposed based on balanced composite right/left-handed (CRLH) transmission lines (TLs) to improve the backward scanning bandwidth and achieve constant gain. The proposed antenna consists of a substrate-integrated waveguide (SIW) unit cell array configured by an H-shaped slot cut in the top layer of the SIW and a patch embedded beneath the H-shaped slot. The proposed design improves the backward scanning bandwidth compared to planar SIW LWAs. The measured beam radiation is in the range from −79° to 80° over the frequency range of 7.6–12.5 GHz. Moreover, a constant gain of greater than 10 dB is achieved over the entire X-band frequency range.

A Low-Profile Dual-Polarized Substrate Integrated Magneto-Electric Dipole MIMO Antenna

A magneto-electric dipole (MED) MIMO antenna with low-profile, dual-polarized, and substrate integrated properties is proposed. The antenna element is composed of four fan-shaped patches lying on the radiation plane and four vertical metal vias linking the patches and the ground. Compared with the common MED antennas, the proposed MED antenna element has a lower profile of 0.1λ. Besides, it is fed by microstrip lines via two orthogonal H-shaped slots, resulting in a broad impedance bandwidth of 40% (3-4.5 GHz) and a steady gain in the entire operational band. The ports isolation is higher than 27 dB, the cross-polarization discrimination (XPD) is higher than 37 dB, and the measured radiation efficiency is greater than 70%. Furthermore, four antenna elements are utilized to form a MIMO antenna, which can obtain better ports isolation characteristics under the condition that the element spacing is half wavelength. Finally, the MIMO antenna is simulated, fabricated and measured. The results verify the rationality of the design.

H-Shaped Slot Antenna with Harmonic Tuning Function and Integrated Power Amplifier

This study proposes a patch antenna with an H-shaped slot with direct matching and harmonic tuning (rejection) functions for microwave power transfer. This antenna enables an integrated active antenna in which the power amplifier and antenna are directly connected without using a matching circuit for the fundamental frequency and harmonic rejection filter to improve the efficiency of the amplifier. The integrated design also reduces the total size of the amplifier and antenna, allowing for a higher-density array antenna. Characteristic mode analysis was performed to explain the working principle of the harmonic rejection function. The designed antenna at 5.8 GHz was fabricated to study its harmonic tuning function. The magnitude of the reflection coefficient of the proposed antenna was at a fundamental frequency of −40.4 dB for an amplification device with an optimum load impedance of 100 Ohm. At the second harmonic frequency, the magnitude and phase of the reflection coefficient at the second harmonic frequency were −0.79 dB and −177.6°, respectively; at the third harmonic frequency, they were −0.92 dB and −179.5°, respectively. Finally, the designed antenna was integrated into an amplifier circuit to verify that it achieved similar drain efficiency as when using the impedance tuner. It was confirmed that the harmonic rejection function of the proposed antenna increases the drain efficiency of the integrated power amplifier by 5.5%. The measurements revealed that this antenna is suitable for use in microwave power transfer because of its fundamental matching and harmonic-processing capabilities.

A Fixed-Frequency Beam-Scanning Leaky-Wave Antenna Using Phase and Amplitude Control for Millimeter-Wave Applications

A new type of fixed-frequency beam-scanning leaky-wave antenna (LWA) in Ka millimeter-waveband is developed in this article, based on dual control of phase and amplitude. The antenna consists of a groove gap waveguide (GGW) and 80 perturbation units. Each unit contains one patch and a pair of H-shaped slots. By controlling the state of a slot with p-i-n diodes, the phase of the radiated field from each unit can be switched between two opposite phases, called “1” state and “−1” state, while the magnitude of the radiated field remains unchanged. In addition, the radiation strength of each unit can be also turned off to provide amplitude control. The main principle for beam scanning is based on the phase compensation to the perturbation units on the surface of the LWA, combined with 1-bit amplitude control to achieve lower sidelobe levels, so the principle is different from that of the existing fixed-frequency beam-scanning LWAs. The entire antenna structure relies on GGW transmission to reduce dielectric loss in millimeter-waveband, and shows good characteristics of scanning angle and realized gain. In the measurement, a high peak gain of 16.8 dBi and a large beam-scanning range over 110° are achieved.

Vertical Waveguide-to-Microstrip Self-Diplexing Transition for Dual-Band Applications

This letter presents a novel vertical waveguide-to-microstrip self-diplexing transition for dual-band applications. The transition is realized with standard printed circuit board (PCB) manufacturing processing, making it suitable for mass production and practical applications. A standard waveguide is screwed on the topside of the stack-up. Dual-band self-diplexing operation is achieved by coupling two microstrips (one for each band) to two radiating patches through H-shaped slots. The operating bandwidth has been enhanced by adding two parasitic patches above the radiating ones. Metalized via holes are used to form a cage around the rectangular waveguide and the microstrips to prevent power leakage. A prototype has been fabricated to operate at K/Ka frequency band. The experimental results show a −10 dB matching bandwidth of 20% and 14% for the lower and upper bands, respectively. Within these ranges, the maximum measured insertion loss is about 0.6 and 0.7 dB, respectively.

An All-Metal, Circularly Polarized Reflectarray Antenna for High-Power Microwave Applications

In order to improve the performance of the existing high-power microwave (HPM) antenna, an all-metal circularly polarized (CP) reflectarray (RA) antenna is proposed in this article. The proposed antenna has 2-D beam-steerable capability up to 60° elevation angle. The RA element employs an H-shaped slot and can be mechanically rotated to obtain continuous 360° phase coverage with negligible element loss. By rotating the individual element, the RA antenna can achieve the dynamical control of the antenna beam. The maximum antenna gain is 33.05 dBi, corresponding to an aperture efficiency of 58.76%. In addition, the simulation results show that the power handling capacity of the RA antenna is over 5 GW/m2 under vacuum condition, which can be applied to the HPM applications.

Gain Enhancement of a Microstrip Patch Antenna with Quasi H-Shaped Slot for UHF RFID Reader

Gain Enhancement of a Microstrip Patch Antenna with Quasi H-Shaped Slot for UHF RFID Reader

Planar Dual-Mode Dipole Antenna Formed by Artificial Microstrip Arms Loaded With Multiple H-Slots for Broadband Operation of Vertically Polarized Radiation on UAV Platform

An antenna design is presented for long-distance transmission in the unmanned aerial vehicle (UAV) application. This antenna is in a dipole configuration but with dual-mode operations of both dipole and monopole mechanisms. The monopole behavior becomes apparent when installed on the UAV platform to provide a large ground. To ensure both modes’ good integration to produce a broad bandwidth, the dipole arms are formed by H-slot loaded microstrips to create a slower phase velocity. The separation between adjacent harmonic resonances can be decreased. This antenna has good vertically polarized radiation and maximum gains near the horizontal plane to provide better long-distance connections. Various combinations of H-shaped slots are applied to examine the bandwidth behaviors. The achieved size is 90 mm, roughly 1/3 wavelengths at 1.25 GHz and 1/4 at 0.8 GHz. The bandwidth is larger than 50%. Numerical HFSS full-wave simulation and measurement results are compared to validate the feasibility.

Energy Harvesting Rectenna Design for Enhanced Node Lifetime In WSNs

With the rising popularity and advent of many services on Wireless Sensor Networks (WSNs), there is a compelling need to have energy-efficient solutions. The sensors and devices are powered by batteries whose life is limited, and at times it is impossible to replace the batteries, especially in remote applications. In such a scenario, Energy Harvesting (EH) stands as an undisputed candidate for enhancing the network lifetime. Radio Frequency (RF) energy is the most commonly available, ubiquitous, and reliable energy source among all the available energy sources. While RF signal carries both information and energy, EH is possible for long-distance and mobile environments. This work discusses initial research in the domain of EH in wireless networks via Radio Frequency (RF) signals. The paper presents an EH rectenna for energy harvesting over 2.45 GHz (Wi-Fi band). The receiving antenna is designed to pick up the radio signal in the RF range (2.45 GHz) from the free space. The four patch elements design has an antenna substrate made with RT with a dielectric constant of 2.2. The paper presents the simulation results of the basic parameters of the antenna, such as return loss, input impedance, bandwidth, gain, directivity, and efficiency. H-shaped slot antenna and modified H-shaped antenna (with circular slot) are designed with a gain of 8.24 dB and 8.32 dB, return loss of -10 dB and -16 dB, and bandwidth of 64.8 MHz and 868 MHz. The high gain, large bandwidth, properly matched impedance for minimum return loss, and high efficiency of the modified H-shaped patch antenna makes it eligible for energy harvestin.

Dual-band measurement of complex permittivity in a microwave waveguide with a flexible, thin and sensitive metamaterial-based sensor

A dual-band metamaterial-based sensor is proposed to determine the complex dielectric constant of ethanol-methanol mixtures. The original sensor structure incorporates one connected dual H-shaped slot resonators at the center and one H-shaped slot resonator at the left and right sides of a rectangular copper patch to provide two distinct resonance frequencies. Polycarbonate is chosen as the substrate material due to its lightness, flexibility, robustness and transparency. Full-wave simulations of electric field distributions reveal that the dual resonances at 3.7 GHz and 4.6 GHz stem from different parts of the metamaterial. Measurements are carried out with a WR-229 microwave waveguide and the electromagnetic simulation results are confirmed with good agreement. A first-order equation that relates the complex dielectric constant to the shift of resonance frequency and peak attenuation is used to determine the complex dielectric constant of ethanol-methanol mixtures in the vicinity of 3.3 GHz and 4.4 GHz frequencies. A good agreement with the literature values is obtained validating the accuracy of the used model. Experimental results revealed that the frequency detection resolution and sensitivity parameter values of the proposed sensor are 25.3 MHz and 0.73% for the lower-frequency band and 9.6 MHz and 0.22% for the higher-frequency band, respectively. In addition to being able to operate at dual frequencies, the proposed metamaterial-based sensor has high sensitivities for the two resonance frequencies. Moreover, the advantages of the proposed sensor, as being electrically-small, flexible, noncontact and reusable, provide a good option for discrimination of binary liquid mixtures at multiple frequencies.

Z-Shaped Metasurface-Based Wideband Circularly Polarized Fabry–Pérot Antenna for C-Band Satellite Technology

This research proposes a low-profile Z-shaped metasurface (MTS)-based wideband circularly polarized (CP) Fabry–Pérot antenna for C-band satellite communication. The proposed low-cost and low-complexity CP Fabry–Pérot antenna is realized by using three substrate layers: upper, middle, and lower. The substrates are of FR-4 type with a dielectric constant of 4.3 and loss tangent of 0.025. The upper substrate contains 9 × 9 periodically-arranged Z-shaped MTS unit cells functioning as the partially reflecting surface and circular polarization conversion, and at the center of the middle substrate sits a corners-truncated square patch. The lower substrate consists of a copper plate with an H-shaped slot at the center of the ground plane and a microstrip feed line. The lower and middle substrates function as the source antenna. The periodic Z-shaped MTS unit cells are utilized to enhance the impedance bandwidth (IBW) and gain of the source antenna and also to convert linearly polarized into CP wave. The antenna dimension is 1.5λ0 × 1.5λ0 × 0.51λ0. Simulations are performed and experiments carried out. The measured IBW and axial ratio bandwidth are 64% (4.4 – 7.6 GHz) and 18% (4.4 – 5.3 GHz) at the center frequency of 5 GHz. In addition, the proposed antenna scheme achieves a measured 3-dB boresight gain bandwidth of 30% (4.3 – 5.8 GHz) with the maximum gain of 12.88 dBic at 4.7 GHz, rendering the proposed Z-shaped MTS-based CP Fabry–Pérot antenna operationally suitable for satellite communication. In essence, the novelty of this research lies in the use of the low-cost and low-complexity Z-shaped MTS unit cell to effectively enhance the antenna gain and convert LP into CP wave.

C-SRR loaded CBCPW fed H-shaped slot radiator for ECG monitoring

C-SRR loaded CBCPW fed H-shaped slot radiator for ECG monitoring

C-SRR loaded CBCPW fed H-shaped slot radiator for ECG monitoring

C-SRR loaded CBCPW fed H-shaped slot radiator for ECG monitoring

A Wideband Antenna for mm-Wave Antenna-in-Package Application

Antenna-in-Package has been widely applied for millimeter-wave systems that integrate the MMIC chip and antenna into one package. For organic substrate Antenna-in-Package solutions, probe feeding and aperture-coupled feeding patches are generally used as radiation units. In this work, a patch antenna is proposed using coupled resonation; a wideband, high-gain and compact 3-D antenna package integration is realized. An equivalent circuit model is analysed for the coupled structure. λ/4 coupled line is adopted for impedance matching, the whole antenna is designed on the same thick radiation patch substrate, with less organic substrate lamination layers. For millimeter-wave Antenna-in-Package structures, vias are generally used for vertical interconnections, which function well in the lower millimeter-wave frequency range. For operation frequency higher than 100GHz, design difficulties may be encountered for via interconnection, with performance degeneration on impedance matching and transmission loss. This work integrates a H-shaped slot instead of vias on an organic substrate, realizing a high frequency and wideband mm-wave transition. An interconnection structure is also adopted to convert a microstrip line to differential microstrip line in the feeding network. Antenna prototype with 2×4 radiation array is designed for verification purpose at 20GHz frequency range with simulated bandwidth of 23%. The prototype is fabricated with separate PCB boards assembled with screws, measured antenna gain is 12.7dBi-13.5dBi. The proposed structure provides a wideband and low-loss solution for potential higher frequency mm-wave Antenna-in-Package applications.

A wideband MIMO antenna with high isolation for 5G application

This letter presents a design of four-element wideband multiple-input-multiple-output (MIMO) antenna with improved isolation that covering 1.9–5.2 GHz for 5G application. The basic structure of the proposed MIMO antenna is meandering monopole; a dual-band is generated by involving meandering L-shape strip and inverted-F strip, then coupling with a parasitic strip to generate wideband. By etching two H-shape slots and two split-ring resonator slots at the ground can enhance the isolation between two adjacent input ports. Antenna elements are rotated symmetrically and vertically distributed around the dielectric plate, the overall dimension of the MIMO array is 54 mm × 120 mm × 13 mm. Reasonable layout can reduce the user's influence on the antenna performance, so that each antenna element can work normally. The prototype is simulated, fabricated and measured. A good impedance matching (return loss <− 10 dB), high isolation (<−16 dB), high total efficiency (>65%), and low envelope correlation coefficient (ECC < 0.05) were obtained across the operation bandwidth, the gain of the antenna is 6.1 dB at 3.6 GHz. Through measurement, it is found that the results are basically consistent with the simulation results, indicating that both wide bandwidth and high isolation are successfully achieved and can be well applied in 5G communication.