Aperture-coupled Patch Research Articles

16-Port Cavity-Backed Aperture-Coupled Patch Antenna for On-Antenna Power Combining

16-Port Cavity-Backed Aperture-Coupled Patch Antenna for On-Antenna Power Combining

Dual-mode aperture-coupled patch resonator based dual-band higher-order frequency selective surfaces

In this article, a low profile aperture coupled dual band higher order bandpass frequency selective surface (FSS) is proposed. To begin, a simple patch resonator with an L-shaped truncated corner is theoretically examined such that two orthogonal modes can be activated at the same time. Following that, a combination of four identical L-shape truncated patch resonators with 90° rotation between two adjacent patches is developed and analyzed to avoid the reflection of cross-polarized produced by orthogonal modes. Further, by arranging two of such combination resonators placed back-to-back through aperture coupling metallic layer in the middle, a three layer single mode fourth order bandpass FSS is designed. The proposed bandpass FSS is twice the performance of traditional aperture coupled patch resonators (AC-PRs). It provides more flexibility at higher order filtering responses. To endorse the design concept, a dual-band fourth order bandpass FSS is simulated to initiate magnetic and electric coupling through the aperture metallic layer. Moreover, an equivalent circuit model for even and odd mode analysis is examined for the principle of operation. Finally, the proposed bandpass FSS is fabricated and tested in a vector network analyzer (VNA) setup. The measured and simulated results are compared and validated.

Higher Order Bandpass Single and Dual Band Frequency Selective Surfaces With Aperture Coupled Patch Resonators

Higher Order Bandpass Single and Dual Band Frequency Selective Surfaces With Aperture Coupled Patch Resonators

Aperture-Coupled Beam-Scanning Patch Array With Parasitic Elements Using a Reconfigurable Series-Fed Phase-Shifting Structure

In this letter, we propose a reconfigurable series-fed phase-shifting structure with movable metal plate for active millimeter wave beam-scanning application. The proposed phase-shifting structure can be equivalent to a certain number of phase shifters in the series-fed network. It can be easily controlled with only one metal plate, which further simplify the design of control system for phase shifters and reduce the cost. A prototype of 1-D aperture-coupled patch array with parasitic elements at 28GHz is designed, fabricated and measured for verifying the performance of the proposed phase-shifting structure. The measurement results at 28 GHz show 1-D beam-steering capability with maximum steering angle of ∼22 deg at H-plane can be achieved, revealing great potentials for developing the simple control and cost-effective active phased array for millimeter wave wireless power transmission application.

A D-Band 16-Element Phased-Array Transceiver in 55-nm BiCMOS

A 16-element 140–160-GHz phased array transceiver is reported. The chipset is fabricated using STMicroelectronics’ 55-nm SiGe BiCMOS process. Five different chips are implemented: a 4-channel transmitter with a maximum gain per channel of 15 dB and 0-dBm saturated output power; a 4-channel receiver with a maximum gain of 8 dB, a −10.4-dBm input 1-dB compression point (IP1 dB), and a minimum noise figure (NF) of 15.6 dB per channel; a 0–1-GHz to 140–160-GHz I/Q up-converter with integrated frequency doubler, exhibiting a −13.5-dB conversion gain (CG) and −6-dBm output 1-dB compression point using a 70–80-GHz local oscillator (LO); a 140–160-GHz to 0–1-GHz I/Q down-converter with integrated frequency doubler, exhibiting a CG of 0 dB and IP1 dB of 0 dBm using a 70–80-GHz LO and an 11.67–13.33-GHz to 70–80-GHz x6 frequency multiplier for the LO, delivering 5.6-dBm maximum output power. The chips are assembled together with 16 cavity-backed aperture-coupled patch antennas using a high-performance and low-cost commercial PCB, supported over a heat sink. The main challenges encountered during the integration of the proposed system are also discussed. The complete system is used to build a wireless radio link in the laboratory, demonstrating 2-D beam steering in a range of ±30°.

A Wideband Amplifying Reconfigurable Intelligent Surface

We present a C-band amplifying reconfigurable intelligent surface (ARIS) integrated with power amplifier (PA) to enhance the reflected electromagnetic (EM) signals. An aperture-coupled patch element with two orthogonal hourglass-shaped slots is elaborately constructed to ensure a broad operation bandwidth. A power combining and dividing network is also introduced to combine the 2 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times2$ </tex-math></inline-formula> elements into a subarray to reduce the number of PAs and the system cost. The simulation results indicate that the achieved gain of ARIS is 7.7–12.2 dB from 5.0 to 6.0 GHz. A prototype of the proposed ARIS is designed, fabricated, and experimentally verified. The measured results agree well with the simulation. The proposed ARIS is promising for applications in future wireless communication systems for signal enhancement and coverage extension.

A Multipolarized Planar Phased Array for LEO SATCOM Applications

This letter presents a scalable multipolarized planar phased array for the low earth orbit satellite communication application. A dual-polarized aperture-coupled patch element antenna is proposed for designing the array, which can provide dual-linear polarization (LP) and dual-circular polarization (CP). The rotated feed technique is adopted to reduce the cross-polarization level. By using 8-channel beamformer chips and the multilayer printed circuit board technology, a phased array prototype with good electromagnetic shielding performance, high integration, and low cost is designed, fabricated, and measured. For dual-LP radiation, it steers up to the scan angles (±50°) with a scan loss less than 3.5 dB, and a cross-polarization level lower than −30 dB in azimuth/elevation plane and −15 dB in diagonal plane. For dual-CP radiation, it steers up to the scan angle (±50°) with a scan loss less than 3 dB and an axial ratio less than 3 dB. The phased array developed in this letter can be scaled to larger arrays and provides feasibility for the production of low-cost phased arrays.

Aperture-Coupled Patch Antenna With Flat-Top Beam for Microwave Power Transmission

This letter presents a flat-top radiation transmitter (Tx), which is composed of 2 × 2 array patches connected to the ground plane of the aperture by four shorting vias, which can generate a mushroom structure resulting in back lobe level reduction. The final design exhibits an overall size of 1.93 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\lambda _{0}$</tex-math></inline-formula> × 1.93 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\lambda _{0}$</tex-math></inline-formula> × 0.075 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\lambda _{0}$</tex-math></inline-formula> at 5.8 GHz. The measured results agree well with the simulated results, which achieves a maximum left-hand circular polarization gain of 8.5 dBi with a sidelobe level of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$&lt; $</tex-math></inline-formula> −13.5 dB, and 3 dB beamwidths of 80 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> in both the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E-</i> and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H-</i> planes. Moreover, the proposed transmitter is tested with the rectenna showing that a stable received energy of 5.93 mW is obtained with an exciting 1 W input power in case of receiving antenna lateral misalignment of up to 60 mm, which demonstrates feasibility in practical deployment. Compared with the other works, the proposed antenna has the advantage in compactness and wide 3 dB beamwidth.

Broadband Dual-Polarized Aperture-Coupled Patch Antenna for 5G Applications

Abstract: This paper presents the design of a dual-polarized aperture-coupled microstrip antenna array for Sub-6GHz 5G communication systems. The antenna operates at 3.5 GHz and consists of 4×4 square patches. The proposed 4×4 array antenna feds by aperture-coupled feed line provide broadband bandwidth to operate in the N78 sub-6GHz 5G frequency band. The dualpolarized is presented, which gives two communications channels. The antenna consists of three layers and is designed on Rogers RO4003C substrate with a dielectric constant of 3.55 and substrate thickness of 0.8 mm. The final design of the antenna array with an overall size of 269 mm × 269 mm × 12.5 mm, and the results show that the 4×4 array has a 10dB bandwidth between 3.3-3.8 GHz and a maximum gain of 14.9 dB at 3.5 GHz, and the isolation between the two ports was 30 dB. The proposed antenna's gain, radiation efficiency, and bandwidth satisfy the requirements of 5G base station systems.

Dual-Band Circular Polarizers With Versatile Polarization Conversions Based on Aperture-Coupled Patch Resonators

In this article, a class of low-profile dual-band circular polarizers based on aperture-coupled patch resonators (ACPRs) are proposed to achieve versatile linear-to-circular polarization (LP-to-CP) conversions. Initially, a dual-band dual-polarized bandpass frequency-selective surface (FSS), consisting of a composite array of two independent ACPRs subelements, is presented to obtain the desired transmission properties for vertically and horizontally polarized incident waves. The equivalent circuit model is then introduced to analyze the proposed FSS, exhibiting that transmission magnitude properties of vertically and horizontally polarized transmitted waves can be independently designed within these two passbands. Furthermore, two pairs of rectangular slots are introduced in the patches of these ACPRs subelements and extensively investigated to demonstrate that versatile phase differences between vertically and horizontally polarized transmitted waves with equal magnitude can be achieved. Based on this concept, within these two passbands, a right- or left-hand circularly polarized (RHCP or LHCP) transmitted wave is then attained by designing the vertical and horizontal components of a 45° tilted LP incident wave with equal magnitudes and ±90° phase difference, thus leading to dual-band LP-to-CP polarization conversions. To validate the design concept, two prototypes of dual-band circular polarizers with orthogonally and identically LP-to-CP conversions in each operation band are designed, fabricated, and measured. Experimental results have well revealed that our proposed structure has a few attractive advantages of ultrathin profile, low axial ratio, and flexible designs in LP-to-CP conversions and frequency band ratios.

A Simple Structure Dual-Band Dual-Circularly Polarized Antenna With Controlled Frequency Ratio

This paper proposes a dual-band dual-circularly polarized (CP) aperture-coupled patch antenna with flexible frequency ratio. By simply etching a modified S-shaped slot at the central of a circular patch, dual-band dual-CP operation is realized. In addition, the frequency ratio of the two CP bands can be flexibly controlled by optimizing the length parameters of the S-shaped slot arms. As a result, the frequency ratio can be tuned from 1.12 to 1.46 according to different requirements. For demonstration, the circularly polarized patch antenna operating at 3.42 and 3.85 GHz is manufactured and tested. The measured 3-dB axial-ratio (AR) bandwidth is 1.1% and 2.3% for the right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP), respectively. The measured gains at the lower and upper bands are 9.4 and 9.8 dBic, respectively.

Wideband Dual-Circularly Polarized Antennas Using Aperture-Coupled Stacked Patches and Single-Section Hybrid Coupler

This paper presents a dual-circularly polarized (dual-CP) antenna with simple configuration, low-profile, and wide bandwidth. Its primary radiating element is an aperture-coupled patch loaded with a stacked patch for a wide operational bandwidth. A single-section hybrid coupler is utilized as a feeding structure of the antenna to generate dual-CP radiation. Different from the priors normally requiring both wideband radiator and wideband feeding structure, this work demonstrates that the wideband dual-CP radiation can be obtained by combining a wideband radiator and a conventional hybrid coupler. A design operating at the center frequency of 5.5 GHz has been fabricated and tested. The measurements result in a &#x2212;10-dB reflection coefficient bandwidth of 30.0&#x0025; (4.66 &#x2013; 6.31 GHz), a 10-dB isolation bandwidth of 30.9&#x0025; (4.66 &#x2013; 6.35 GHz), a 3-dB axial ratio (AR) bandwidth of 29.1&#x0025; (4.70 &#x2013; 6.30 GHz), and a realized broadside gain of 5.5 &#x2013; 7.05 dBic. For a more robust dual-CP radiation, a low-sidelobe 4 <inline-formula> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 4 element array of the proposed antenna has been designed, fabricated, and measured. Compared to the single element design, the array prototype yields similar impedance and 3-dB AR bandwidths, but a higher isolation. The measurements on the array prototype result in an isolation of <inline-formula> <tex-math notation="LaTeX">$\geq 14$ </tex-math></inline-formula> dB, a peak gain of 16.3 dBic, a side-lobe level of <inline-formula> <tex-math notation="LaTeX">$\leq -20$ </tex-math></inline-formula> dB, and a cross-polarization of <inline-formula> <tex-math notation="LaTeX">$\leq -16$ </tex-math></inline-formula> dB across the frequency range of 4.7 &#x2013; 6.3 GHz (29.1&#x0025;).

Reconfigurable Circular-Ring Feed Patch Antenna with Tri-Polarization Diversity

In this paper, a reconfigurable circular-ring feed patch antenna for polarization diversity applications is proposed. The reconfigurability is realized by using only two p-i-n diodes which are inserted into the circular feed ring of the aperture-coupled patch antenna. With the help of the p-i-n diodes, the polarization of the antenna is able to be altered among 45° linearly polarized (LP), left-hand circularly polarized (LHCP), and right-hand circularly polarized (RHCP) states. A fully-functional prototype is fabricated and measured. The measurement agrees well with the simulation and three polarization states are obtained. Owing to the merits of tri-polarization diversity, low profile and simple structure, the proposed design is a great candidate for future wireless systems.

High-Order Bandpass Polarization Rotator Based on Aperture-Coupled Patch Resonators

In this letter, a low-profile 90° polarization rotator with a fourth-order bandpass filtering response is proposed by using aperture-coupled patch resonators elements. The presented polarization rotator is constituted on a five-layer structure consists of two orthogonal rectangular apertures etched on two different layers, and are sandwiched between two single-mode square patch resonators and a dual-mode corner-truncated square patch resonator. Moreover, the property of 90° polarization rotation is obtained by properly exciting two orthogonal modes within the corner-truncated square patch resonator and the polarization selective characteristic of two orthogonal rectangular apertures. The proposed polarization rotator is designed and analyzed with the direct coupling matrix method. To validate the design concept, a design example is fabricated and measured. Measured results well reveal that our proposed structure has its attractive advantages of ultrathin profile, high-order filtering response, high polarization purity, and stable performance under oblique incidence.

Double-Curved Metal in Multilayer Printed Circuit Boards for Bandwidth Enhancement of Millimeter-Wave Patch Antennas

Metal curving or metal denting is usually an unwanted phenomenon in the printed circuit board (PCB) process. However, curved metal could provide some benefits to enhance performance of radio frequency components. In this article, an approach is proposed to develop a double-curved metal (DCM) in a multilayer PCB process by allocating a metal upon an air cavity and then laminating with buffer layers under suitable pressure and temperature. This approach could increase the degree of freedom on radio frequency component design in PCB process. Based on this approach, a millimeter-wave (mmWave) aperture-coupled patch antenna is produced with the improved characteristics of high gain, wide bandwidth, and compact size. Prototypes of the proposed antenna are designed, manufactured, measured, analyzed, dissected, and observed under a metallographic microscope. The measurements and simulations are in good agreement and demonstrate that the proposed antenna achieves a maximum gain of 8 dBi over an operating bandwidth of 27.4-34.2 GHz. Compared with an aperture-coupled patch antenna with a flat metal, the fractional bandwidth of that with a double-curved metal is enhanced by a factor of two.

Study on Millimeter-Wave SIW Rectenna and Arrays With High Conversion Efficiency

A novel aperture-coupled patch rectenna backed by a substrate integrated waveguide (SIW) cavity operated at 35 GHz for millimeter-wave power transmission (MMPT) with high conversion efficiency is presented in this article. A four-element SIW patch array with a harmonic suppression function based on the barbell-type defect ground structure (DGS) is proposed as the receiving antenna; thus, the low-pass filter in the rectifying circuit can be omitted. The Schottky diode is parallel-mounted in the rectifying circuit, which has a measured rectifying efficiency of 61.2% with a 500 Ω load when the received power is 100 mW. The maximum conversion efficiency of the rectenna element is 60.9% when the received power is 79.4 mW. Additionally, 4-8-and 16-element rectenna arrays are also investigated to obtain high direct current power. When the power density is 9.2 mW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , the conversion efficiencies of the rectenna element, 2×2 array, 2×4 array and 2×8 array are 50.5%, 44.1%, 41.9%, 38.9%, respectively. The measured conversion efficiency of the 2×8 rectenna array at 35 GHz is 49.2% when the input power is 1259 mW. The low profile and easy integration of the studied rectenna will make it easy to expand its use to large-scale arrays for high-power MMPT applications.

A Novel Sensor-Integrated Aperture Coupled Microwave Patch Resonator for Humidity Detection

Wireless sensor elements integrated with miniaturized antennas are useful in various applications such as wearable chemical and environmental sensors and Internet-of-Things (IoT) sensor nodes. A major problem in antenna operation is detuning of the antenna bandwidth due to loading by the sensor element. In this article, we report on the integration of an interdigitated capacitor (IDC), acting as a sensor, into an aperture coupled patch (ACP) antenna, such that weak coupling is established between the IDC and the rectangular patch resonator. Because of low mutual coupling, during the sensing process the antenna is not detuned out of its operational bandwidth and its performance is not compromised by the presence of the sensor and vice versa. A sensing material (barium titanate film) is deposited on the IDC located at the edge of the microstrip line used to slot-feed the ACP antenna. A change in the material permittivity is transduced into a variation of resonant frequency of the antenna. We describe the design and fabrication of the IDC sensor-integrated ACP antenna and demonstrate the measured sensing performance at different temperatures and relative humidity concentrations.

Dual-Polarized Antenna Gain Enhancement Using Dielectric Slab Superstrate and its Application in Forming an Array

The use of dielectric slab superstrate (DSS) is proposed for gain enhancement of dual-polarized patch antenna and the corresponding arrays. The DSS for a single antenna is investigated firstly to lay a solid foundation for the design of DSS for large arrays. The DSS is placed in front of the dual-polarized aperture-coupled patch antenna and is proved to be available for gain enhancement for both polarizations. The measured results show that the DSS has little effect on the impedance bandwidth but can increase the gain by 10.7 and 11.2 dB for the two ports, respectively. Different from the existing research work, the DSS used to enhance the gain for large arrays is discussed. A piecewise homogeneous DSS with slots is proposed and fabricated for 2 ×2 array with a measured peak gain of 18.3 and 18.4 dBi for two polarizations. The piecewise homogeneous DSS and source antenna array hold the advantages of high gain, large aperture efficiency and easy processability. The piecewise homogeneous DSSs for 4×4 and 8×8 array are also designed and the simulated results show that the DSS can be effective for larger arrays.

Design of a continuously tunable reflectarray element for 5G metrology in the k-band

Abstract. We introduce a new tunable reflectarray element for an operation frequency of 26 GHz in the k-band. It is shown that a 340∘ continuous tunning range of the reflected wave can be accomplished by using an aperture-coupled patch antenna with only one single varactor diode. The simplified design and the small needed space make it usable for k-band reflectarrays with many elements. The functionality of the reflectarray element is explained and the crucial parts are analyzed. The approach to get a full phase shift is discussed in detail. A bias-T is developed to provide the control voltage to the varactor diode without interfering with the high frequency path. The high frequency path and the DC-path are decoupled by 39 dB using a bias-T. A commercial off-the-shelf varactor diode is selected and its functionality at 26 GHz is verified. Therefore, a test printed circuit board with through, reflect, line standards is developed to de-embed the varactor diode and to evaluate it with a vector network analyzer. The reflectarray is simulated in a unit cell with plane wave excitation and periodic boundary condition using the simulation software package CST Microwave Studio™.

A method for increasing the bandwidth of slot and patch antennas using grid‐slotted patch

A method for expanding the bandwidth of slot and patch antennas is proposed in this article. The use of grid-slotted patch helps to improve the impedance matching of the antenna, thus the bandwidth can be extended. The design process and an analysis of using a grid of slots to increase the bandwidth of a slot antenna is first given. The simulated S11 of the broadband slot antenna is less than −11 dB in the range of 2.6 to 3.42 GHz. To further demonstrate the method, an aperture-coupled patch antenna with grid-slotted patch is designed. The measured S11 of the broadband patch antenna is less than −10 dB in the range of 1.95 to 4.15 GHz and the peak gain is 9.6 dBi.