Aperture-coupled Stacked Patch Research Articles

A Sub-Terahertz Wideband Stacked-Patch Antenna on a Flexible Printed Circuit for 6G Applications

In this article, a wideband aperture-coupled stacked-patch (ACSP) antenna on a flexible material for wireless applications at the WR-08 band is presented. It is shown that conventional designs of ACSP fail to achieve a large bandwidth at this frequency range, and a novel design methodology is proposed. We first propose a broadband impedance matching between the input port and the slot aperture based on two-section wideband distributed network (TWBDN). We also propose a TWBDN matched stacked patch (TMSP) network based on constant VSWR circles to attain broadband matching between the slot aperture and patches in an ACSP. To facilitate the measurements, a novel low-loss transition from a ground-signal-ground (GSG) port to a feedline is proposed. The proposed structure suppresses surface waves induced in the WR-08 band by placing via arrays around the feedline, which largely reduces unwanted resonance modes, thereby leading to uniformly high radiation efficiency across the band. The measured results of the fabricated antenna closely follow the simulations, and a measured peak gain of 7.95 dBi and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$S_{11}\leq -10$ </tex-math></inline-formula> dB across a wide frequency range from 90 to 128.5 GHz is achieved.

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;).

A Hybrid Antenna in Package Solution Using FOWLP Technology

Abstract Widespread millimeter wave applications have promoted rapid development of system in package (SiP) and antenna in package (AiP). Most AiP structures take the form of flip chip onto antenna substrate, where signal interconnect losses are introduced by solder bumps. The integration may be unavailable for chips with fine pad pitches. Fan-out wafer level package (FOWLP) with antenna patterning on redistributed layers (RDL) is another method for millimeter wave AiP. In this project, a hybrid integration AiP structure is developed. The microwave monolithic integrated circuit (MMIC) chip and antenna unit are integrated with chip-first FOWLP process. Multilayer organic substrate with fine pitch RDL interconnections meets the requirements of wideband antenna design. Modified coplanar waveguide is adopted to feed 2 × 2 aperture array formed on RDL layer. Package warpage is measured using Shadow Moire techniques. The antenna forms an aperture-coupled stacked patch array with bandwidth 25% and gain 8.5dBi for 60 GHz digital communication system. The proposed approach is a convenient hybrid integration solution adopting FOWLP process for millimeter wave AiP systems.

A Millimeter-Wave Multibeam Transparent Transmitarray Antenna at Ka-Band

This letter presents a transmitarray antenna (TA) in the 27.5–29.5 GHz frequency band. The proposed TA is optically transparent and offers the possibility of steering the beam in the H -plane from –30° to 30°. One can achieve these properties using a novel unit cell, composed of meshed double-circle rings printed on polymethylmethacrylate substrates, a plastic material transparent to visible light. This unit cell provides a phase shift of 300° for an insertion loss lower than 1 dB at 28.5 GHz. In turn, the TA sources consist of 2 × 2-element arrays of aperture-coupled stacked patch antennas. The choice of a patch array over a horn array allows one to reduce the total profile and weight of the TA. We have fabricated and tested a transparent TA with a diameter of 9.9 wavelengths at 28.5 GHz, yielding a broadside gain of 25 dBi and –1 dB gain bandwidth of 1.8 GHz; the off -axis 30° beam presents a peak gain of 21.5 dBi and –1 dB gain bandwidth of 1.4 GHz. The measured results are in good agreement with the simulated ones all over the frequency band of interest.

A Shaped-Beam Stripline-Fed Aperture-Coupled Stacked Patch Array

A shaped-beam stripline-fed aperture-coupled stacked patch (ASP) array is presented. First, it is proposed to use stripline-fed ASP antennas as the array elements. Then, in order to achieve the severe amplitude variation in the aperture distribution of the shaped-beam pattern, a simple and efficient procedure is proposed to improve the coupling coefficients of the stripline elements. The experimental results of the array showed that good shaped-beam patterns were achieved in a 3.8% frequency band.

Wideband Offset Slot-Coupled Patch Antenna Array for X/Ku-Band Multimode Radars

A high-gain, wideband antenna element that covers most portions of X- and Ku-bands is essential for multimode radar applications. This letter presents an aperture-coupled stacked patch antenna for 8.75-12.25-GHz frequency band. Fixed beam tilt up to 30 ° in scan range can be obtained by offsetting the aperture relative to a driven patch. When there is no offset, a single antenna has broadside gain greater than 10 dBi. An antenna array (4 × 4) with fixed beam tilt is designed and validated with measurements. The prototype antenna exhibits 44% fractional bandwidth and maximum gain 20.6 dBi in the target frequency band.

A SHAPED-BEAM SERIES-FED APERTURE-COUPLED STACKED PATCH ARRAY ANTENNA

A shaped-beam series-fed aperture-coupled stacked patch array antenna at X-band is presented. To improve the array bandwidth, two-port aperture-coupled stacked patch antennas, which are suitable for the series-fed array conflguration, are presented as the radiating elements. To ofier the pattern design and optimization progresses more ∞exibility, a uniformly spaced array conflguration is applied in the shaped-beam pattern design, instead of the conventional nonuniformly spaced array conflguration. The experimental results show that, in a 7.6% bandwidth, the main beam shape of the array maintains in good agreement with the design goal, and the side lobe level maintains lower than i18dB.

On the Use of U-Slots in the Design of Dual-and Triple-Band Patch Antennas

The general method of using U-slots to design dual- and triple-band patch antennas is described. In this approach, one starts with a broadband patch antenna, which can consist of one or more patches. When a U-slot is cut in one of the patches, a notch is introduced into the matching band, and the antenna becomes a dual-band antenna. If another U-slot is cut in the same patch or in another patch, a triple-band antenna results. This method is applied to the L-probe-fed patch, the M-probe-fed patch, as well as the coaxially fed and aperture-coupled stacked patches. It is found that the patterns and gains of the dual-and triple-band antennas are similar to those of the original broadband antenna. Because the band notches introduced by the U-slots occur within the bandwidth of the antenna without slots, this method is suitable when the frequency ratios of the adjacent bands are small, usually less than 1.5.

CPW-Fed Stacked Microstrip Antennas

This paper presents a systematic parameter study of aperture-coupled stacked patch antennas fed by coplanar waveguide. These antennas are to be used at millimeter-wave frequencies in the 30-GHz range. The influence of the most important design parameters, such as patch dimensions, aperture dimensions, and substrate thicknesses, was studied extensively. It has been found that these antennas can easily be impedance-matched by tuning the dimensions of the excitation slot and adding a small tuning stub. In this way, an antenna element with a -10 dB impedance bandwidth of 36.8% has been designed. Furthermore, the results of this parameter study have allowed to formulate some general guidelines concerning the design of this type of antenna element.

A broad-band dual-polarized microstrip patch antenna with aperture coupling

In this communication, a dual-polarized aperture-coupled microstrip patch antenna with a broad-bandwidth high-isolation low cross-polarization levels, and low-backward radiation levels is designed and its features are presented. For broad bandwidth and easy integration with active circuits, it uses the aperture-coupled stacked patches. The corner feeding of square microstrip patches is applied and the coupling aperture is the H-shaped aperture. The theoretical analysis is based on the finite-difference time-domain (FDTD) method. A dual-polarized antenna is designed, fabricated, and measured. The measured return loss exhibits an impedance bandwidth of over 24.4% and the isolation is better than 30 dB over the bandwidth. The cross-polarization levels in both E and H planes are better than -23 dB. The front-to-back ratio of the antenna radiation pattern is better than 22 dB. Both theoretical and experimental results for S parameters and radiation patterns are presented and discussed.

Wideband planar sector-based pattern array for indoor RCS measurement

This letter presents the development of a multilayer planar array with 256 antenna printed elements for indoor RCS measurement, operating in a wide frequency range (25%) around 4 GHz. The elementary source is an aperture-coupled stacked patch antenna. The feed network is composed of Wilkinson power dividers and hybrid ring couplers so as to achieve the required complex weightings. Experimental results are presented in the whole frequency band. © 1998 John Wiley & Sons, Inc. Microwave Opt Technol Lett 18: 188–193, 1998.

Design of wide-band aperture-stacked patch microstrip antennas

A variation of the aperture-coupled stacked patch microstrip antenna is presented, which greatly enhances its bandwidth. Bandwidths of up to one octave have been achieved. The impedance behavior of this antenna is compared with that of other wide-band microstrip radiators. Matching techniques for the antenna are presented and their relative merits discussed. The effects of varying several key physical parameters of the antenna are investigated, lending some insight into its wide-band operation. Variations on the design such as incorporation of additional patches are also discussed.

Wideband dual polarised aperture-coupled stackedpatch antenna array operating in C-band

The design and experimental results of a wideband (16 %) and directive (21 dB), dual polarised antenna array are presented in C-band around 6.9 GHz. This compact 8 × 4 element array tapered by a Dolph-Chebyshev distribution (fabricated with Wilkinson power dividers) is composed of dual polarised aperture-coupled stacked patch antenna elements. Use of these elements in the antenna array leads to quite good performance over a relatively wide frequency range.