Aperture-coupled Patch Antenna Research Articles

High-Power, Aperture Coupled Photonic Antenna

A high-power charge-compensated modified uni-travelling carrier photodetector is directly integrated into an aperture coupled patch antenna. The coupling technique offers not only good isolation between feed and radiating patch substrates but also wide operational bandwidth. The antenna is developed to operate at 22 GHz with 3-dB relative bandwidth of ~20%, over which the measured effective isotropic radiated power approaches 31 dBm. The photonic antenna is integrated with a lightweight, low form factor fiber-optic feed that demonstrates potential for future wireless communications applications. The antenna's electrical and radiation characteristics are observed to be in good agreement with simulations.

Experimental study of a wearable aperture-coupled patch antenna for wireless body area network

A new type of the wearable aperture-coupled patch antenna for 2.4 GHz wireless body area network (WBAN) application is proposed. The H-shaped slot in middle ground plane and rectangular ring microstrip feed line are optimized, so that it realizes the efficient electromagnetic coupling with the radiating element. The substrate layers are 2 mm thickness felt layers with relative permittivity of 1.2, and the other layers are copper foil tape (CFT) to ensure the performance of the antenna. Furthermore, the return loss, radiation pattern and gain are investigated in detail for the antenna under different bending curvature radius. Experimental results show a good agreement with simulation results. (C) 2017 Wiley Periodicals, Inc.

Radiation Bandwidth Improvement of Electromagnetic Band Gap Cavity Antenna

Abstract In this paper, an electromagnetic band gap cavity antenna with improved radiation and impedance bandwidths is presented. The proposed antenna is constructed by placing a triple-layer heterogeneous printed-unprinted partially reflective surface (PRS) above a primary aperture-coupled patch antenna. The PRS unit-cell provides a positive gradient reflection phase behavior over the desired frequency range. A prototype antenna is fabricated and measured that highlighted its ability to achieve 3-dB gain bandwidth of about 35.9 %, from 7.93 GHz to 11.4 GHz, with a peak gain of 14.25 dBi at 8.5 GHz. In addition, the impedance bandwidth is 40.32 %, from 7.9 GHz to 11.89 GHz. Thus, the designed antenna outperforms many other competitors for improving the radiation bandwidth of planar antennas with the same presented concept.

A Dual-Polarized Two-Dimensional Beam-Steering Fabry–Pérot Cavity Antenna With a Reconfigurable Partially Reflecting Surface

A dual-polarized two-dimensional beam steering Fabry-Perot cavity antenna with a reconfigurable partially reflecting surface (PRS) is proposed. A polarization reconfigurable aperture coupled patch antenna, which can work in two different linear polarizations, is adopted as the exciter. By controlling the PIN diodes, the PRS can have different reflection phase distributions, giving the antenna different beam tilted states in eight azimuthal directions. The PRS has the same function on different linear polarization waves, so the antenna can realize polarization reconfiguration and beam steering simultaneously. A prototype antenna is fabricated and measured. The measured results show that, beam angles greater than 8° were obtained for each azimuthal direction at 5.5 GHz. Good agreement between the simulated and measured results was achieved, which confirms the correctness of the design principle.

Backlobe and Sidelobe Suppression of a Q-Band Patch Antenna Array by Using Substrate Integrated Coaxial Line Feeding Technique

A low profile aperture-coupled patch antenna array with high front-to-back-ratio (FTBR) is designed at Q -band by using substrate integrated coaxial line technique, the intrinsic shielded enclosure of which is capable of constructing an equal-phase and amplitude-tapering feeding network with backlobe suppression. An illustrative example of a 6 $\times$ 6 patch antenna array is designed and fabricated with a 2 $\times$ 2 prior verification module by using multilayer liquid crystal polymer process. Measured results indicate that the array can achieve a gain of 17.6 dBi at 41.5 GHz and the first sidelobe levels is $-$ 24.1 dB in the E -plane and $-$ 20.4 dB in the H -plane. The holistic FTBR is better than 27 dB in both planes.

A 60‐GHz multi‐beam antenna array design by using MHMICs technology

ABSTRACTThe integration feasibility of two technologies including Miniaturized Hybrid Microwave Integrated Circuit (MHMIC) and Printed Circuit Board (PCB) are experimentally demonstrated at millimeter wave frequencies through the design of a switched beam antenna array. A 1 × 4 array of aperture coupled patch antennas etched on a RO5880 substrate is fed by a 4 × 4 butler matrix etched on a piece of high permittivity ceramic substrate. By using the proposed combined fabrication technologies, the feeding part on the ceramic substrate can be easily integrated with MMIC active component, while the radiation part is individually improved. Comparison of simulated and measured results show that the proposed switched beam antenna offers a −10 dB matching bandwidth of 6 GHz ranging from 58 GHz to 64 GHz and a multi beam radiation pattern which is focused in 45°, 15°, −15°, −45° directions. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1844–1847, 2016

Combining the switched-beam and beam-steering capabilities in a 2-D phased array antenna system

This paper presents the development, fabrication, and measurement of a novel beam-forming system consisting of 16 subarray antennas, each containing four aperture-coupled patch antennas, and the application of this system in smart wireless communication systems. The beam patterns of each of the subarray antennas can be switched toward one of nine zones over a half space by adjusting the specific phase delay angles among the four antenna elements. Furthermore, when all subarrays are pointed at the same zone, slightly continuous beam steering in around 1° increments can be achieved by dynamically altering the progressive phase delay angle among the subarrays. Phase angle calibration was implemented by coupling each transmitter output and down converter into the in-phase/quadrature baseband to calculate the correction factor to the weight. In addition, to validate the proposed concepts and the fabricated 2-D phased array antenna system, this study measured the far-field radiation patterns of the aperture-coupled patch array integrated with feeding networks and a phase-calibration system to carefully verify its spatially switched-beam and beam-steering characteristics at a center frequency of 2.4 GHz which can cover the industrial, scientific, and medical band and some long-term evolution applications. In addition, measured results were compared with calculated results, and agreement between them was observed.

60-GHz LTCC Patch Antenna Array With an Integrated EBG Structure for Gain Enhancement

This letter presents a 60-GHz $2 \times 2$ low temperature co-fired ceramic (LTCC) aperture-coupled patch antenna array with an integrated Sievenpiper electromagnetic band-gap (EBG) structure used to suppress TM-mode surface waves. The merit of this EBG structure is to yield a predicted 4-dB enhancement in broadside directivity and gain, and an 8-dB improvement in sidelobe level. The novelty of this antenna lies in the combination of a relatively new LTCC material system (DuPont Greentape 9K7) along with laser ablation processing for fine line and fine slot definition ( $50-\mu\hbox{m}$ gaps with $+ / - 6 \mu\hbox{m} $ tolerance) allowing the first successful integration of a Sievenpiper EBG structure with a millimeter-wave LTCC patch array. A measured broadside gain/directivity of 11.5/14 dBi at 60 GHz is achieved with an aperture footprint of only $350 \times 410\hbox{mil}^2$ ( $1.78\lambda \times 2.08\lambda$ ) including the EBG structure. This thin (27 mil) LTCC array is well suited for chip-scale package applications.

Time-Modulated Antenna Array With Lossless Switching Network

In this letter, a novel architecture for a time-modulated antenna array (TMAA) based on single-pole double-throw (SPDT) switches is presented. The proposed TMAA has lossless switching network because there is no power loss during the off state. In addition to improved efficiency, this TMAA provides beam-scanning capabilities. Moreover, the proposed TMAA has a constant instantaneous directivity, which is favorable for some applications. The architecture has been implemented as an aperture-coupled patch antenna array and verified as a smart antenna in a digital wireless communication system.

Dual polarised aperture‐coupled patch antenna using asymmetrical feed

Dual polarised antennas are normally fed by symmetrical feed networks in order to obtain symmetrical radiation patterns for two orthogonal polarisations. In this study, a dual polarised aperture-coupled patch antenna using asymmetrical feed for X-band application is proposed. The exploitation of asymmetrical feed structure in exciting dual polarisations turns out to be valid, and is capable of realising symmetrical radiation patterns just as the traditional feed networks have done. Besides, the asymmetrical feed provides a wide impedance bandwidth and high isolation between ports. Key parameters studies and current distributions analysis prove the feasibility of the asymmetrical feed. Both simulated and measured results indicate an impedance bandwidth over 35.2% and the isolation is higher than 30 dB over the entire bandwidth. The cross-polarisation levels in the E- and H-planes for both polarisations are lower than −20 dB. Moreover, the antenna prototype shows good symmetrical property in radiation patterns for dual polarisations.

A Wideband Ultra-Thin Differential Loop-Fed Patch Antenna for Head Implants

An ultra-thin differential patch antenna is proposed for head implants. Through the proximity coupling between the rectangular patch and the loop structure fed by a differential microstrip line, an antiphase mode is excited, which doubles the bandwidth of an aperture-coupled rectangular patch antenna. Moreover, the directional radiation allows maximum energy to be directed to the receiver and lowers the specific absorption rate (SAR). An antenna prototype with an overall size of $24 \times 10 \times 0.95\,\text{mm}^{3}$ exhibits the ${-} 10\,\text{dB}$ reflection bandwidth of $4.1 - 4.5\;\text{GHz}$ , directivity more than 5 dBi, and gain higher than ${-} 8\,\text{dBi}$ at the boresight. The maximum transmit power of 28 mW is permitted for the SAR limit of 1.6 W/kg across the impedance bandwidth.

A C-band microwave rectenna using aperture-coupled antenna array and novel Class-F rectifier with cavity

A rectenna (rectifying antenna) is usually applied to a microwave power transmission (MPT) system as a terminal, which receives microwave (MW) power and converts them into DC power. A 5.8 GHz aperture-coupled patch antenna array is developed with a gain of 19.5 dBi, which is a part of the rectenna. A novel Class-F rectifier with a series diode is proposed to achieve a high rectifying efficiency based on harmonic termination techniques. The input circuit of the proposed rectifier is taken into consideration to reach the Class-F condition, while mostly only the output circuit is involved in conventional Class-F designs. A low-pass filter based on defected ground structure is implemented, which not only blocks the harmonics produced in rectifying but also presents desired impedance at harmonics. The current and voltage waveforms on the diode are well enforced. The radiation feature of the rectifier is presented as well. It shows that an optimized cavity, which shields the parasite radiation, may achieve a 5% enhancement on the MW-to-DC conversion efficiency. A C-band rectifier based on HSMS-286 Schottky diode is fabricated and measured. A MPT simple demo system is constructed with the proposed rectifier and antenna. A measured maximum MW-to-DC conversion efficiency of 72% is achieved on the rectifier. The design method is extremely valuable in a high conversion efficiency rectenna design based on harmonic termination techniques.

Slot‐coupled broadband patch antenna

A wideband aperture-coupled patch antenna is presented. The proposed antenna consists of patches in different sizes and a ground plane, which is fed by a microstrip line through a slot cut on the plane ground. Owing to the patches of different size and the slot on the ground, three resonance modes are excited simultaneously for the radiation at the boresight. The proposed antenna yields a wide bandwidth of about 31% with a low profile of 0.07 λ 0 ( λ 0 is the free space wavelength at the centre operating frequency). The results are validated by both numerical simulation and experimental measurements.

A Broadband V-Band Rectangular Waveguide to Substrate Integrated Waveguide Transition

A broadband air-filled rectangular waveguide to substrate integrated waveguide (SIW) transition is proposed at V-band. By introducing an aperture coupled patch antenna structure into the design, a bandwidth wider than 35% for |S 11 | <; -10 dB is achieved. A back-to-back prototype fabricated by the low-cost printed circuit board (PCB) technology shows that the insertion loss of a single transition is less than 0.58 dB within the bandwidth. With good performance and compact volume, the proposed transition is attractive for millimeter-wave circuit designs and measurements.

High isolation and compact MIMO antenna system with defected shorting wall

In this paper, a compact multiple-input multiple-output (MIMO) antenna system with high isolation is proposed for 2.4 GHz wireless local area network (WLAN) application. The system is composed of two aperture-coupled shorted patch antennas with a spacing of 4 mm (only 0.032λ). The antenna is fed with an H-shaped coupling slot, and the defected shorting wall is used for high isolation. The proposed MIMO system exhibits an isolation of better than −20 dB and a maximum isolation of −43 dB at the central frequency. The envelope correlation coefficient is less than 0.01. The simulated and measured results show that the proposed antenna is a good candidate for MIMO system with higher isolation and better diversity.

Modified Microstrip Aperture Coupled Patch Antenna with Sierpinski Fractal Geometry

A two-layer modified microstrip aperture coupled patch antenna with Sierpinski fractal geometry is presented in this paper. The effects of the two coupling slots and the parasitic patch are discussed. The proposed antenna can work on 956 MHz to 968 MHz, 3.654 GHz to 3.78 GHz, and 8.81 GHz to 9.28 GHz three frequency bands, and the maximum gain in each band is 4.64 dBi, 8.46 dBi, and 7.85 dBi, respectively. The simulated result reveals that the Sierpinski patch antenna we proposed in this paper performs better on radiation properties.

Theory and Experiment of Spherical Aperture-Coupled Antennas

Rigorous mathematical method of moments (MoM) for analyzing spherical microstrip aperture-coupled antennas is presented in this paper by using dyadic Green's functions (DGF) in conjunction with magnetic field integral equation (MFIE) and electric field integral equation (EFIE) formulations. With the aid of linear Rao-Wilton-Glisson (RWG) triangular basis functions, spherical three-layer aperture-coupled patch antennas are analyzed. The effect of mutual coupling between slot and patch antenna is developed and the input impedance and radiation patterns of such an antenna are presented. A prototype of a spherical aperture-coupled antenna is fabricated and tested. The measurement results are compared to the results of the proposed method and a good agreement between the results is achieved. The measured efficiency and gain of this antenna at 3.15 GHz are 85% and 5.23 dB, respectively.

Multilayer Stretchable Conductors on Polymer Substrates for Conformal and Reconfigurable Antennas

Multilayer stretchable conductors (SCs) are demonstrated for the first time as an alternative cost-effective method for implementing conformal and reconfigurable antennas over flexible substrates. Structurally, these SCs are realized on polydimethylsiloxane (PDMS) substrate via single or double copper layers deposited around a commercially available conductive rubber. The dc measurements demonstrate the stretchability of the multilayer SCs up to 25% and 22.5 times larger conductivity as compared to the standalone conductive rubber. The RF performance of these multilayer SCs is first characterized in the 1–5-GHz range by measuring the insertion loss in 50- $\Omega$ microstrip lines. As compared to a standalone conductive rubber, the triple-layer SC has shown 58% less insertion loss. To demonstrate their use in reconfigurable and flexible conformal antennas, an aperture-coupled patch antenna is designed, fabricated, and tested. Specifically, it is shown that the antenna can be tuned from 2.97 to 2.69 GHz when stretched by 9%. Additionally, the patch antenna implemented from the multilayer SC exhibits 6.18 dB realized gain. This gain is 3.71 dB better than that of a patch antenna implemented from a standalone conductive rubber layer, and only 0.4 dB lower than that of a conventional patch.

A Cavity-Backed Aperture-Coupled Microstrip Patch Antenna Array with Sum/Difference Beams

This paper presents a new cavity-backed aperture-coupled microstrip patch antenna (ACMPA) array with sum/difference beams. It is composed of a feed network and two aperture-coupled elliptical patch antennas. A metallic cavity is used at the back of the antenna array to minimize the back radiation. The feed network is realized by a planar magic-T, which consists of microstrip and slotline T-junctions coupled by microstrip-slotline transitions. The antenna is designed, manufactured and tested at 35 GHz. Measurements show clean and symmetrical patterns are realized for both the sum and difference beams. The measured −3-dB E- and H-plane beamwidths of the sum pattern are 55.8◦ and 77.6◦, respectively. A deep null of −32.4 dB is achieved for the difference pattern. Meanwhile, the measured return losses for both the sum and difference ports are less than 10 dB from 34.2–36.6 GHz corresponding to a bandwidth of 6.8%. Within this bandwidth, the isolation between the sum and the difference ports is better than 38 dB.

Reduction in Mutual Coupling Characteristics of Slot-Coupled Planar Antenna due to Rectangular Elements

High frequency bands such as the 3-GHz band have received much attention as frequency resources for broadband mobile communication systems. Radio Frequency (RF) integrated antennas are considered to be useful as base station antennas in decreasing the feeding loss that is otherwise inevitable in high frequency bands and they ensure sufficient power for broadband transmission. One problem in actualizing RF integrated antennas is miniaturizing the duplexer, which is generally large, among the RF circuitry components. To downsize the duplexer, we consider separately locating the transmitter (Tx) and receiver (Rx) antennas. To suppress further the mutual coupling between the Tx and Rx antennas, we investigate a filter integrated antenna configuration. In this paper, we consider an aperture coupled patch antenna as the base antenna configuration and propose a new filter integrated antenna that comprises multiple rectangular elements installed between the coupling slot and radiation element of the Rx antenna. The simulation and measurement results confirm that the new antenna reduces the mutual coupling in the transmission frequency band up to 5.7dB compared to the conventional slot coupled patch antenna configuration.