Wideband Circularly Polarized Patch Antenna Research Articles

Compact Wideband Circularly Polarized Patch Antenna Array Using Self-Sequential Rotation Technology

In this letter, a compact wideband circularly polarized patch antenna array is proposed to cover the 57&#x2013;71 GHz band. The antenna array is constructed by 45<inline-formula><tex-math notation="LaTeX">$^\circ$</tex-math></inline-formula> inclined slits loaded circular radiating patches with rectangular back cavities, two-layer sequential rotation feed networks, and a waveguide transition. Novel self-sequential rotation technology is introduced using a dual-high-order-mode cavity to improve the axial ratio (AR) and impedance bandwidths of the subarray. Compared with conventional sequential rotation feed networks, the proposed feeding scheme provides higher aperture efficiency. A 4 &#x00D7; 4 patch antenna array is fabricated using standard printed circuit board technology. Measured results show that the <inline-formula><tex-math notation="LaTeX">$-$</tex-math></inline-formula>10 dB impedance and 3 dB AR overlapped bandwidth is 23.8&#x0025;(57&#x2013;72.3 GHz). The measured peak gain is 20.5 dBic with an aperture efficiency of 87.7&#x0025; at 66 GHz.

Gain and AR Improvements of the Wideband Circularly Polarized Fabry-Perot Resonator Antenna

A method to improve the performance of a wideband circularly polarized (CP) Fabry–Perot resonator antenna (FPRA) is presented in this communication. First, a wideband CP FPRA composed of a partially reflective surface (PRS) with a positive reflection phase gradient and a wideband CP patch antenna is proposed. Then, a transmission metasurface (MS) with a high transmission magnitude and tunable transmission phase in a broadband range is proposed to correct the electric field phase above the antenna. This MS has the ability to independently tune the transmission phases of two orthogonally polarized waves. On the one hand, the nonuniform phase distribution on the aperture field of the antenna can be transmitted to be nearly uniform, so the gain of the antenna will be enhanced. On the other hand, the transmission phases of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$x$ </tex-math></inline-formula> - and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$y$ </tex-math></inline-formula> -polarized waves are corrected to maintain a 90° phase difference at every position, which leads to a wider axial ratio (AR) bandwidth. Therefore, after the phase correction of the MS, the gain and AR performances of the antenna are both improved significantly. The measured results suggest that the overlap of the 10 dB return loss bandwidth, 3 dB gain bandwidth, and 3 dB AR bandwidth of the antenna is 9–11.1 GHz (21%). The peak gain of 18.3 dBic is achieved at 10.2 GHz. The results indicate that the proposed MS can achieve excellent performance improvement of the CP FPRA.

A Low-Profile and Wideband Circularly Polarized Patch Antenna Based on TM11 and TM21

In this article, a low-profile and wideband circularly polarized patch antenna is proposed and developed, which is composed of the circular patch fed by four ports. A wideband property is achieved by utilizing TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> and TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> mode, as well as the orthogonal mode of TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> . The Γ-shaped feed is employed to stimulate the TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> mode. Besides, due to the parasitic radiation from the face-to-face Γ-shaped feeds with opposite phase, the radiation peak of the circular patch under TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> mode is along the broadside direction, which is different from the original radiation mechanism of TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> mode. By loading shorting pins in the middle area of circular patch, the polarization orthogonal mode of the fundamental mode (TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> ) is excited properly, which contributed to bandwidth enhancement. Cooperated with the quadrature phase feed network, a wideband circular patch antenna with unidirectional radiation and circular polarization properties is designed, fabricated, and measured. The size of the circular patch is 0.57λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ×0.57 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> and the height is only 0.053λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ( λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> is the free space wavelength at the center frequency). The measured results show that the 109% of fractional bandwidth is obtained under the condition of VSWR <; 2, ranging from 0.94 to 3.18 GHz, and the 3 dB axial ratio fractional bandwidth is 95%, ranging from 1.04 to 2.93 GHz. Besides the realized LHCP gain >3 dBic from 1.27 to 2.99 GHz.

S-Shaped Metasurface-Based Wideband Circularly Polarized Patch Antenna for C-Band Applications

This research proposed an S-shaped metasurface (MTS)-based wideband circularly polarized (CP) patch antenna for C-band uplink frequency spectrum. The proposed MTS-based CP patch antenna was of low profile and fabricated on three substrate layers: upper, middle, and lower. The upper substrate contained 4 × 4 periodic S-shaped MTS elements, the middle substrate functioned as ground plane with a rectangular-shaped slot at the center, and the lower substrate contained a coplanar waveguide with microstrip and ground. The S-shaped MTS elements converted linearly polarized (LP) into CP wave. Simulations were performed, and an antenna prototype was fabricated and experiments carried out. The measured impedance bandwidth and axial ratio bandwidth (ARBW) at the center frequency of 5.9 GHz were 43.22% (4.05 - 6.6 GHz) and 22% (5.3 - 6.6 GHz), respectively, rendering the proposed antenna suitable for satellite communication applications. The proposed antenna achieved the maximum gain of 6.16 dBic at 5.6 GHz. The novelty of this research lies in the use of S-shaped MTS elements to efficiently convert LP into CP wave and achieve wider ARBW for the C-band uplink spectrum.

A Wideband Circularly Polarized Patch Antenna With Enhanced Axial Ratio Bandwidth via Co-Design of Feeding Network

A wideband circularly polarized (CP) patch antenna with enhanced axial ratio (AR) bandwidth via co-design of feeding network is proposed in this paper. One $\pmb \lambda/4 $ resonator and one $\pmb \lambda/2 $ resonator are introduced and coupled in proximity to two orthogonal points of a square patch radiator to excite two orthogonal modes. These two resonators not only function as impedance matching elements to achieve equal magnitude of two orthogonal modes in a wide frequency band but also provide the required 90° phase difference. In this way, two minima in the AR response appear, resulting in extended AR bandwidth. The wideband design of the antenna is carried out based on the equivalent circuit model, where the patch radiator is treated as a conductance, inductance, and capacitance parallel resonator. In particular, the feeding network and the patch are jointly considered as a three-port network for synthesis design. By mapping the radiated far field to the magnitude and phase on the radiation conductance in the circuit model, the AR response of the antenna becomes predictable in a straightforward manner. Measured results experimentally demonstrate that the 3-dB AR bandwidth of our proposed CP patch antenna is 2.7 times that of the traditional one fed with two 90° offset lines.

Compact Wideband Circularly Polarized Patch Antenna for CNSS Applications

A compact wideband circularly polarized (CP) patch antenna utilizing a quad-feed network (QFN) and quadruple semi-fan-annulus (QSFA) patches is proposed. For using a coupled-line dual-band power divider (PD) and improved phase shifter (PS) with stepped-impedance-open-stub (SIOS), the QFN has a compact size and exhibits the electromagnetic (EM) simulated bandwidth over 96% for the power distribution -6.5±0.5 dB, return loss (RL) > 14 dB, and a consistent 90° (±9°) phase deviation. Moreover, the QSFA patches can expand the CP bandwidth and reduce the size of the antenna effectively. Measurement results show that the proposed antenna achieves CP bandwidth of 72% from 1.15 to 2.45 GHz for RL > 10 dB, axial ratio dB, and 3-dB gain variation (gain > 4.4 dBi). Therefore, the proposed antenna is a good candidate for Compass Navigation Satellite System (CNSS) applications.

A Wideband Circularly Polarized Patch Antenna for 60 GHz Wireless Communications

This paper presents the design of a fully packaged 60 GHz wideband patch antenna incorporating an air cavity and a fused silica superstrate. Circular polarization (CP) is realized by introducing a diagonal slot at the center of the square patch. By optimizing the patch and the slot dimensions, a high efficiency (>90%) microstrip fed CP antenna with an impedance bandwidth of 24% and a 6 dB axial ratio bandwidth of 21.5% is designed. A coplanar waveguide (CPW) to microstrip transition with λ/4-open-ended stubs are then designed to match the antenna to the CPW packaging interface. The experimental results of the final packaged antenna agree reasonably with the simulation results, demonstrating an impedance bandwidth of more than 26% and a 6 dB axial ratio bandwidth of 22.7%.

Wideband Circularly-Polarized Patch Antenna

A novel wideband circularly-polarized patch antenna is presented. First, a new broadband 90deg hybrid feed network is proposed to have a bandwidth of 75% for the 10-dB return loss, good two output ports amplitude balance and a consistent 90deg (plusmn3deg) phase difference between two output ports. Then, a circular patch antenna fed by four sequential-rotation proximity-coupled L-probes orientated to have phase of 0deg, 90deg, 180deg and 270deg is presented. The four L-probes are connected to the respective ports of a feed network comprising a pair of the proposed broadband 90deg hybrid. It is found that the antenna can deliver a measured impedance bandwidth of 79.4% from 1.04 to 2.41 GHz for SWR<2, measured 2-dB and 3-dB axial-ratio bandwidths of 57% from 1.3 to 2.35 GHz and 82% from 1 to 2.4 GHz, respectively, and a measured gain bandwidth of 56.1% from 1.26 to 2.32 GHz for gain>3 dBi. The simulated impedance bandwidth is 94% from 0.9 to 2.5 GHz for SWR<2. The simulated 3-dB axial-ratio bandwidth is 63.8% from 1.25 to 2.42 GHz. The simulated gain bandwidth is 59.3% from 1.33 to 2.45 GHz for the gain>3 dBi. Good agreement is observed between simulation and measurement

A novel wide-band circularly polarized patch antenna based on L-probe and aperture-coupling techniques

The design and measurements of a wide-band patch antenna with circular polarization are presented. For the proposed antenna, an L-probe and an aperture are utilized to feed the patch orthogonally. The distance between the patch and the ground plane is 0.1 free-space wavelength at 1.8 GHz. Air is used as the dielectric substrate. A Wilkinson power combiner is connected to the feeds to generate circular polarization. The antenna possessed a 14-dB return loss bandwidth of 35% (from 1.49 to 2.12 GHz), and has a 3-dB axial ratio bandwidth of 20.4% (from 1.67 to 2.05 GHz). The 3-dB axial ratio beamwidth and the boresight axial ratio are 84/spl deg/ and 1.94 dB at 1.8 GHz, respectively.