Stacked Patch Antenna Research Articles

A Bendable Wideband Dual-Polarization Conformal Phased-Array Antenna

In this letter, we proposed a bendable wideband dual-polarization low-profile conformal phased array antenna. The antenna element is an Invert-F fed stacked-patch antenna. It provides an active VSWR < 3 for 10.7 GHz to 12.75 GHz in the principal planes. The proposed phased array antenna employs a row modular architecture, which enables it to bend to a cylindrical geometry. Both the antenna aperture and the active components of the conformal phased array antenna are considered for bending in the letter. A prototype conformal phased array antenna with 8 rows of 4 dual-polarization antenna element was fabricated, assembled and measured. Wide-angle beam scanning is achieved by electronically scanning along the curved axis of the cylindrical conformal phased array antenna. Moreover, there is no grating lobe when scanning down to 60°.

A Circularly Polarized Stacked Patch Antenna for Dual Band L1 &amp; L2 GPS Applications

A Circularly Polarized Stacked Patch Antenna for Dual Band L1 &amp; L2 GPS Applications

Wideband Single-Fed Circularly Polarized Stacked Patch Antenna With L-Shaped Stub

A wideband single-fed circularly polarized (CP) stacked patch antenna with an L-shaped stub is presented. The CP antenna is made up of the bottom gradient microstrip transmission line, middle driven patch and top square radiation patch. The driven patch with an L-shaped stub and opening slot can achieve a wideband CP radiation which is different from a conventional patch. The presented CP stacked patch antenna maintains good directional radiation, while featuring wideband CP radiation. The final tested results indicate that the presented CP antenna has significant performance with a −10 -dB impedance bandwidth of 42.1% (4.26-6.53 GHz), a 3-dB AR bandwidth of 26.0% (4.36-5.66 GHz) and broadside peak gain of 8.6 dBic. Moreover, the fifth-generation (5G) N79 band (4.4-5.0 GHz) and 5G wireless local area network (WLAN) band (5.15-5.35 GHz) can be covered by the operating bandwidth of the presented CPantenna.

A Dual-Polarized Aperture-Sharing Phased-Array Antenna for 5G (3.5, 26) GHz Communication

Integrating the sub-6 GHz antenna and the millimeter-wave (mm-wave) antenna in one radiating aperture is a promising approach to support different frequency bands for the incoming communication system. In this paper, an mm-wave dual-polarized 64-element phased-array antenna is integrated into the partially reflective surface (PRS) of a sub-6 GHz resonant cavity antenna (RCA). The PRS consists of two multi-layer printed circuit boards (PCBs), which are stacked together and connected by solder joints. The thick PRS unit cell is designed with a miniaturized footprint at 3.5 GHz and can also contain a 2 × 2 mm-wave active subarray, including four stacked-patch antennas, a beamformer IC (BFIC), and some other input circuits. A copper plate is also inserted in the PRS for thermal control. A prototype antenna is fabricated and measured. Measurement results agree well with the simulation. In the sub-6 GHz band, the proposed antenna demonstrates dual-polarized radiation over the frequency band from 3.45 GHz to 3.58 GHz. In the high-frequency band, the dual-polarized mm-wave array driven by the built-in active beamforming network is capable of scanning ± 45° both in azimuth and elevation over the frequency band from 24.5 GHz to 27 GHz.

A Flat-Panel 8 × 8 Wideband K-/Ka-Band Dual Circularly Polarized Phased Array Antenna for CubeSat Communications

A novel flat-panel 8×8 wideband dual circularly polarized electronically-scanned phased array antenna is proposed, which covers the satellite communications bands of 22.55–23.55 GHz and 25.5–27.5 GHz. A circularly polarized stacked microstrip patch antenna is used as the element radiator with a structural modification on the parasitic patch to minimize gain variation. Since the axial ratio (AR) bandwidth of the element radiator is inherently narrow, sequential rotation is employed to yield a wide AR bandwidth while forming the 2×2 subarray, which is then used as a building block to construct the larger 8×8 phased array. The phased array has a simulated scan range of ±51°, ±46° and ±36° at 23 GHz, 24 GHz and 26.5 GHz, respectively, assuming ≤3-dB scan loss and AR. A beamforming network (BFN) is integrated within the stackup of the phased array that comprises a commercially available silicon beamforming chip. This facilitates beam steering through the independent control of the input amplitudes and phases of the individual element radiators. The practical effects of the BFN on the scanning performance of the 8×8 phased array is studied, which is found to slightly degrade the scan ranges. Finally, experiments were performed on the fabricated prototype, and the measured scan data showed good correspondence with their simulated counterparts with >41° and 35° scan ranges (in +θ direction) at 24 GHz and 26.5 GHz, respectively. The corresponding EIRp and G/T of the 8×8 phased array are also estimated through measurements.

A High-Gain Circularly Polarized Filtering Stacked Patch Antenna

A high-gain circularly polarized (CP) filtering stacked patch antenna with independently controllable radiation nulls is designed without an additional filtering circuit/network in this letter. The lower radiation patch consists of a square outer loop and a three-quarter circular inner ring to realize CP radiation, with the inner ring connected to two adjacent edges of the outer loop. In addition, the upper stacked patch provides improved impedance matching and CP characteristics within the passband. Furthermore, a U-slot and square annular slot are etched on the lower and upper patch to generate two radiation nulls and obtain a filtering characteristic in the lower and upper stopband, respectively. A prototype is fabricated and measured, and the measured results show that the proposed antenna can provide an impedance bandwidth of 15.2% (1.83-2.13 GHz), an axial ratio bandwidth of 8.2% (1.87-2.03 GHz), and a gain higher than 7.0 dBi.

Low profile conformal phased array with wide scanning range

AbstractA linearly polarized conformal phased array antenna with a low profile and a large scanning range is proposed, based on stacked patch antenna element fed by a coupled microstrip line. A backed compact cavity is designed in the antenna element, to reduce the mutual coupling between the elements. The prototype of the proposed conformal array, a conformal array composed of 4 × 4 elements which are axially mounted onto a cylindrical surface, is fabricated and measured, whose profile is as low as 0.072 λh (λh is the free‐space wavelength at the highest operating frequency). The experimental results demonstrate that the array achieves active VSWR below than 2.5 over the frequency band of 1.52–1.77 GHz (15%), within the wide‐scanning ranges of ±70° in the E plane and ±60° in the H plane, and the measured results are in good accordance with the calculation.

Broadband Dual-Polarized Antenna With Stable Radiation Patterns for Base Station Applications

A broadband differentially fed slant ±45° dual-polarized stacked patch antenna is presented to cover 2.3–5 GHz for base station applications. In this letter, both semicircular and sector loaded slotlines are employed to generate three resonant frequencies. A slotted ring is utilized to generate a new resonant frequency, and could make the radiation patterns stable at high frequencies. To verify antenna performances, the proposed design is fabricated. From measurement, it is seen that its relative impedance bandwidth achieves 75.9% (2.28–5.07 GHz), and its port isolation reaches more than 35 dB. Moreover, in the whole band, the gain variation is smaller than 0.8 dB. Therefore, the proposed design could provide great candidate for LTE/5G base station applications.

3D Printed Spin‐Decoupled Transmissive Metasurfaces Based on Versatile Broadband Cross‐Polarization Rotation Meta‐Atom

AbstractThis article proposes 3D printed broadband transmissive metasurfaces for spin‐decoupled wavefront shaping based on a versatile broadband cross‐polarization rotation meta‐atom. A meta‐atom combining broadband cross‐linear polarization dynamic phase and Pancharatnam–Berry (P–B) phase is demonstrated to realize spin‐decoupled beam shaping. The meta‐atom is built in an antenna‐circuit‐antenna fashion. Stacked patch antennas are used here as both the receiving and transmitting antennas because they can achieve wide bandwidth and good impedance matching to free space. By carefully selecting the phase delay lines’ path, the meta‐atom converts the x‐polarized or y‐polarized linear incident wave to its cross‐polarization with the co‐polarized components suppressed. The function also leads to the spin conversion for the circularly polarized incident wave. Thus, P–B phase‐shifting will be introduced when the meta‐atom is rotated. In addition, the transmission line provides the same dynamic phase delay for both left‐ and right‐hand circular polarization (LHCP and RHCP) incident waves. Then, combining the two different phase‐shifting methods, i.e., the P–B phase and dynamic phase, the LHCP and RHCP wavefront can be fully decoupled. Two different metasurfaces achieving spin‐decoupled anomalous refraction carrying orbital angular momentum (OAM) with different topological charges are simulated and experimentally verified for demonstration.

CMA-Based Quadruple-Cluster Leaf-Shaped Metasurface-Based Wideband Circularly-Polarized Stacked-Patch Antenna Array for Sub-6 GHz 5G Applications

This research proposes a quadruple-cluster leaf-shaped metasurface (MTS)-based circularly-polarized (CP) stacked-patch antenna array with hybrid coupler feed network for sub-6 GHz 5G applications. In the study, the leaf-shaped MTS-based CP stacked-patch antenna is characterized by characteristic mode analysis (CMA). In the antenna design, one cluster of the quadruple-cluster leaf-shaped MTS-based antenna array consists of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4\times4$ </tex-math></inline-formula> leaf-shaped MTS elements; and the hybrid coupler feed network is used to enhance impedance bandwidth (IBW), axial ratio bandwidth (ARBW), and antenna gain. Simulations are carried out and an antenna prototype is fabricated and experiments undertaken. The measured IBW, ARBW, and maximum gain at the center frequency (4 GHz) are 62.5% (3.4– 5.9 GHz), 21% (3.8– 4.54 GHz), and 9.04 dBic at 3.9 GHz. The novelty of this research lies in the use of: (i) the CMA concept to design and develop the leaf-shaped wideband MTS-based stacked-patch antenna with CP radiation pattern; and (ii) a low-complexity hybrid coupler feed network to enhance the IBW, ARBW and gain.

MULTIFREQUENCY STACKED PATCH ANTENNA ANALYSIS

In this paper, the theoretical and simulated results of a quad-band patch antenna without any air/foam gap between the dielectric layers are discussed. The design idea uses a skated dielectric layers to achieve a multi-frequency operation. The antenna under study includes four patches patterned on the top of layered dielectric substrates and is stacked vertically. Two pairs of spaced slits are embedded at the patch's radiation edges of the bottom and second patches to adjust the resonant frequencies. The resonant frequencies of the different patches are obtained at 4 GHz, 5 GHz, 6 GHz, and 7 GHz. According to the cavity theory and equivalent circuit approach, a theoretical model of the multilayer stacked patch antenna (MLSPA) is determined. Theoretical and simulated return loss plot is presented to validate the proposed design. The antenna parameters such as radiation pattern, gain, voltage standing wave ratio (VSWR), and beam-width are also discussed. Good impedance matching and radiation characteristics at the four operating bands make this antenna a good candidate for many applications. The antenna simulations are performed using a high frequency structure simulator (HFSS) 15.0 tool.

A Novel Programmable Stacked Patch Antenna With the Diversity of Sixteen Linear Polarizations and Four Frequency Bands

A highly multifunctional antenna with multilinear polarizations (MLPs) and multibands (MBs) is proposed, which can operate over four reconfigurable frequency bands, each band having 16 switchable linear polarizations (LPs) at an 11.25° interval. The larger number of MLPs is achieved by developing an odd–even switching strategy for the independently controlled p-i-n diodes placed between the inner patch and outer sector patches. The diode control is enabled by a field programmable gate array (FPGA) with an engineered biasing network. Moreover, the reported antenna can switch among four continuous bands for each LP, covering a combined range larger than 35%. It is an attractive feature, yet a challenging task for an antenna with such a large number of MLPs. This is realized by utilizing a double-layer feeding strategy with appropriate sector-patch activation, which is particularly appealed to such a highly multifunctional antenna. Furthermore, the antenna has a rotational symmetry along the azimuthal direction and, hence, all the LPs show almost rotationally invariant pattern shapes and gains. The measured results are consistent with the simulated ones, commonly validating the effectiveness of our design.

High Aperture Efficiency Arced Conformal Array With Phasor Beam Steering Antenna

A phasor beam steering stacked patch antenna with abilities of both the amplitude and phase pattern reconfigurations is proposed and used for improving the aperture efficiency of arced conformal array. The phasor beam steering antenna is composed of two parasitic patches on the top integrated with four PIN diodes and a driven patch on the lower layer. By switching the bias states of the PIN diodes, the induced complex current of the top patch is alterable and the phasor beam steering can be delivered. Thus, in the conformal array design, the phase compensation can be realized by the phase pattern reconfiguration of the phasor beam steering antenna instead of the conventionally used phase delay lines. Meanwhile, the amplitude pattern reconfiguration of the phasor beam steering antenna can also be used for enhancing the contribution of side elements to the gain of axial beam. A four-element arced conformal array with the phasor beam steering antenna is designed and measured for verification. Both the simulated and measured results indicate that the realized gain of the proposed conformal array is 12.0 dBi, and the corresponding aperture efficiencies are improved up to 51.48%, which is better than the results of the arced conformal array with the phase compensation network.

Dual-Band 28- and 39-GHz Phased Arrays for Multistandard 5G Applications

This article presents a 32-element 28/39-GHz dual-band phased array for fifth-generation (5G) communication systems. The array is based on separate sets of SiGe transmit/ receive (Tx/Rx) beamformer chips to realize independent dual-beamforming capabilities at orthogonal linear polarizations. The beamformer chips are integrated with an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8 \times 4$ </tex-math></inline-formula> dual-band stacked patch antenna array on a low-cost printed circuit board (PCB) and grouped together using two different Wilkinson networks to form two separate beamforming systems. The dual-band array demonstrates a measured effective isotropic radiated power (EIRP) of 40–42 dBm at the 28- and 39-GHz bands. The array is capable of scanning ±55° in the 28-GHz band and ±40° in the 39-GHz band, both in the azimuth plane. In simultaneous dual-frequency dual-beam operation with the 28-GHz band on the V-pol. and the 39-GHz band on the H-pol., spectrum measurement shows that the array has no visible intermodulation products between the 28- and 39-GHz beams. Also, complex modulation measurements with 64-QAM waveforms show < 3% error vector magnitude (EVM) at an EIRP of up to 36-dBm EIRP for both beams radiating together and without interference with each other. This work demonstrates the first millimeter-wave (mm-wave) 5G dual-band array and paves the way toward multistandard systems.

An Approach to Achieving Multiple Mutual Coupling Nulls in MIMO Stacked Patch Antenna for Decoupling Bandwidth Enhancement

To suppress mutual coupling among multiple-input multiple-output (MIMO) stacked patch antennas, a decoupling method achieving three mutual coupling nulls is proposed by utilizing one pair of symmetrical half-wavelength strips and a dual-hole single-pad structure. The first two mutual coupling nulls are caused by path cancellation after utilizing the two half-wavelength strips. The third one is triggered by phase cancellation of the driven and parasitic patches, and can be controlled by the dual-hole single-pad structure. Compared with the reported decoupling designs on stacked patch antennas, the proposed one can achieve wider decoupling bandwidth, higher isolation improvement, and no profile enhancement. The mutual coupling level of the two-element stacked patch antenna integrated with the proposed decoupling method can be decreased from −21.5 dB to −36.5 dB over the effective frequency range from 3.28 GHz to 3.6 GHz or 9.3%. Afterward, the proposed method is also proved to be effective in four-element stacked patch antenna.

A Low-Cost SISL Differentially Fed Dual-Polarized Stacked Patch Antenna With Enhanced Common-Mode Suppression Using Characteristic Mode Analysis

A wideband differentially fed dual-polarized stacked patch antenna with high common-mode (CM) suppression is proposed in this article using the characteristic mode analysis (CMA) and the substrate integrated suspended line (SISL) technology. Based on the CMA, orthogonal slots are loaded within the stacked patch to enhance the directivity of the second-order degenerate modes and reallocate the resonating frequency of the fundamental degenerate modes. A crossed dipole is introduced within the driven patch to ensure polarization uniformity between the two paired degeneracies. The CM suppression level ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{S}_{\mathrm {CC}}11$ </tex-math></inline-formula> ) is enhanced from–10 to–1.30 dB within the frequency range of 4.0–7.0 GHz by embedding circular slots embedded within the stacked patch and controlling the slot radius. Measured results demonstrate a–10 dB differential impedance bandwidth of 28.4% (4.62–6.18 GHz) and high isolation of better than–39.5 dB between the differential ports. The antenna depicts stable measured radiation patterns with low cross-polarization (<–30 dB). The measured average antenna gain and efficiency are 9.55 dBi and 85.5% within the DM passband. In addition, a high <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{S}_{\mathrm {CC}}11$ </tex-math></inline-formula> better than–1.05 dB is measured within the desired DM band.

Study on a Multi-Point Differential Feeding Strategy for Design of Filtering Patch Antennas With Stopband Enhancement

In this article, a novel multi-point differential feeding technique is introduced and applied in the design of filtering patch antennas with a wide upper stopband. Different from the traditional differential feeding structure, the proposed method has four physical feeding points on the patch. Our analysis results indicate that the proposed feeding approach can not only effectively excite the desired fundamental TM <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\mathbf {01}}$ </tex-math></inline-formula> mode but also flexibly allow for the elimination of high-order modes by selecting suitable feeding positions. Just relying on this feeding method, unwanted harmonic radiations can be totally removed up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4{f} _{\mathbf {0}}$ </tex-math></inline-formula> without any additional elements. For demonstration, a prototype of a stacked patch antenna with filtering response has been then designed. With resorting to the proposed feeding scheme, both driven and stacked patches are indeed able to support good excitation of TM <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\mathbf {01}}$ </tex-math></inline-formula> mode with other harmonics to be suppressed, leading to a wide upper stopband performance. In addition, several radiation nulls are generated in the stopband to improve the filtering selectivity. Measured results agree well with the simulated ones, indicating that the designed differential antenna possesses enhanced fractional impedance bandwidths, high in-band gains, low cross polarization, as well as intrinsic wide stopband rejection, further verifying the proposed feeding concept.

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.

Design of Inverted Stacked Parasitic Patch Antenna for Communication in White Space TV Band

The proposed work aims to design and develop stacked parasitic microstrip antenna configurations in the TV white-space frequency band, which can work between 470 to 806 MHz for applications like IEEE 802.11. The antenna is designed for both the base station (higher gain) and the user terminal (compact). In this design, two layers are stacked on each other with coaxial feed at the lower circular patch. The two top circular patches are placed in an inverted position and electromagnetically coupled with a lower patch. The substrate used is FR4. The proposed antenna can operate between 499 to 650 MHz frequency band with 5.6dBi gain. The proposed antenna is having an efficiency of 98%. A parametric analysis is done to cater to the requirements of the antenna size, gain, and radiation pattern. The parametric study found that when both top patches are elliptical, the lowest size with the largest gain is achieved.

A sequentially rotated feeding circularly polarized stacked patch antenna array based on SISL

AbstractA sequentially rotated feeding circularly polarized stacked patch antenna and its array based on substrate integrated suspended line (SISL) are presented. The resonant frequencies of 5.05 and 5.35 GHz are obtained by using the cross slot on the driven patch, which can also realize circular polarization. The windmill stacked patch is introduced to generate another resonant frequency of 5.85 GHz and expand 3‐dB axial ratio (AR) bandwidth (BW). The measured 10‐dB impedance BW of 18.2% (4.98–5.98 GHz) and the 3‐dB AR BW of 3.6% (5.45–5.65 GHz) are obtained from the proposed antenna element. The measured peak gain is 9.0 dBi. A sequentially rotated feeding is used to excite the proposed 2 × 2 antenna array. The measured peak gain is 13.31 dBi. The measured 10‐dB impedance BW is 28.3% (4.80–6.38 GHz) and the 3‐dB AR BW is 8.9% (5.35–5.85 GHz).