Circularly Polarized Antenna Array Research Articles

Design of RCS Reduction Applied to W-Band Circularly Polarized Antenna Array

A single-layer capsule-shaped polarization conversion metasurface (PCM) is proposed in this paper. In the W-band, its polarization conversion rate (PCR) exceeds 97%, effectively changing the polarization direction of the incident wave. PCM is arranged in a chessboard array to achieve broadband RCS reduction. Placing the PCM array on a circularly polarized sequentially rotated slot antenna array, simulated results show that the radiation characteristics of the antenna array are hardly affected by the PCM array. The results of measurement demonstrate that the RCS of the antenna array with PCM array proposed is reduced by more than 10 dB from 40 to 119 GHz; the relative bandwidth (−10 dB) reaches 96.3%.

Novel 2 × 2 square slot circularly polarized antenna array with wideband characteristics

In this paper, a novel 2 × 2 square slot wideband circularly polarized antenna array (CPAA) is proposed. The antenna consists of a sequential rotation feeding structure, four asymmetric U-shaped feeding strips and a slotted ground plane formed by four square slots with cut corners, four rectangular slots, and four L-shaped strips. In contrast to the traditional L-shaped feeding strips used in CPAAs, an asymmetric U-shaped feeding strip is, for the first time, presented to improve the antenna performance. By using these strips and slots as perturbation elements, the slotted CPAA is able to stimulate multiple circular polarized (CP) radiation modes, resulting in wideband CP radiation. The measured results revealed that the 3-dB axial-ratio (AR) bandwidth for AR < 3 reached 81.3% (1.75–4.15 GHz), whereas the −10-dB impedance bandwidth (|S11| < −10 dB) reached 88.6% (1.96–5.08 GHz).

A broadband circularly polarized magneto-electric dipole array antenna for 5G millimeter-wave applications

A millimeter-wave (mm-wave) broadband circularly polarized (CP) magneto-electric (ME) dipole array antenna is proposed. The antenna element consists of a ME dipole, a direct T-shaped probe, and a pair of shorted parasitic elements. The shorted parasitic elements are employed to ensure a considerable expansion of the 3 dB axial ratio (AR) bandwidth to lower frequencies. As a result, the ME dipole antenna element achieves a wide overlapped AR/impedance bandwidth of 56.89% (22.45–40.3 GHz). Based on the proposed CP antenna element, a 2 × 2 CP array antenna that incorporates an improved X-shaped power divider network is developed. A prototype of the 2 × 2 CP array antenna is fabricated and experimentally verified. The measured results indicate that a −10 dB impedance bandwidth of 50.39% (23.9–40 GHz) and a 3 dB AR bandwidth of 50% (24–40 GHz) are achieved, forming a broad overlapped AR/impedance bandwidth of 24–40 GHz, which covers most of the current mm-wave 5G bands. Moreover, a peak gain of 14.88 dBic is also observed. Thus, the demonstrated antenna with broadband CP operation and good radiation performance can be an excellent candidate for 5G mm-wave applications.

A W-Band High-Efficiency Multibeam Circularly Polarized Antenna Array Fed by GGW Butler Matrix

In this letter, a high-efficiency multibeam circularly polarized (CP) antenna array with the groove gap waveguide (GGW) feeding technology for W-band application is proposed. First, a wideband CP septum antenna element based on GGW structure is proposed. The antenna has a simple structure with high tolerance, and the GGW technology reduces the machine difficulty, making the antenna easier to work in the higher frequency. Next, a 4 × 4 GGW Butler matrix is designed to feed the antenna array. Finally, a high-efficiency W-band four-beam CP endfire antenna array is fabricated and measured. Measured results verify that the antenna has a wider impedance bandwidth of 17.6% from 77.5 to 92.5 GHz for |S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> | <; -10 dB. The measured AR values of the main lobe range of four beams are almost less than 3 dB. Also, stable radiation patterns are obtained. The maximum gain and radiation efficiency are 15.29 dBic and 89.6%, respectively.

A wide-band circularly polarized antenna array using a sequential phase feed structure applied to 5G-band

In this article, a 2×2 broadband circularly polarized antenna array using the sequential rotation (SR) technique in the feed network is presented. This antenna covers the 5G-band of 3.5–3.6 GHz and 4.8–4.9 GHz. So, it can be used for 5G-band communication [1]. The performance of the antenna is obtained by simulation and experiment, as follows: the bandwidth of S11 parameter below -10 dB is 3.7 GHz (3.3–7 GHz), and AR bandwidth (AR < 3 dB) is 2.4 GHz (3.5–5.5 GHz and 5.8-6.2 GHz ), the maximum gain is about 10.2 dBi, and the gain is greater than 0 dBi in the range of 3.6–6.5 GHz.

A right‐handed circularly polarized array antenna based on gap waveguide technology at 35 GHz

AbstractIn this article, the authors have proposed a right‐handed circularly‐polarized array antenna with gap waveguide (GWG) distribution network at 35 GHz. By using GWG technology, the strict electrical contact of different layers is not required so that the expensive vacuum welding or the diffusion bonding technology can be avoided. The entire geometry consists of the top radiation layer and two distribution network layers on the bottom. The aperture shape of the top radiation layer has been designed as a hexagon in order to generate the circular‐polarized electromagnetic waves. The final measurement results show that the reflection coefficient of the whole array antenna is below −10 dB with 8.45% bandwidth where the axial ratio is less than 2 dB. The antenna efficiency is higher than 70% over the whole operating frequency band, and the corresponding antenna gain is higher than 30.8 dBi.

Circular Polarization Array Antenna with Triplate Stripline Elliptic Resonator Antennas

This paper presents a plane antenna and array for X-band circular polarization. The novel factors of this development are elliptic resonator antenna and Glass-Epoxy substrates. High efficiency in resonance and radiation of microwave energy is expected by elliptic resonators. Easy process in fabrication is expected by Glass-Epoxy substrate. Elliptic ratios of feed- and reactance-elements are chosen independently each other. The dielectric constant εr and tan δ are 4.6 and 0.010 respectively. Enough bandwidth of axial ratio of circular polarization and directive gain are confirmed to be 15 % of central frequency and 10 dB respectively for antenna array.

Basic Study of a Monopulse DOA Estimation Circularly Polarized Array Antenna Integrated with Magic-Ts

Basic Study of a Monopulse DOA Estimation Circularly Polarized Array Antenna Integrated with Magic-Ts

High-performance dual circularly-polarized antenna arrays using 3D printing for 5G millimetre-wave communications

In this paper, we propose a 3D-printed millimeter-wave (mmW) antenna array with high performance for 5G applications. In order to enhance the gain by reducing the feed loss, high-order mode cavity backed cross-dipole antennas were deliberated. By adopting the 3D printing, a layer-driven air-filled waveguide feeder with a tailor-made hybrid coupler were designed so a high efficiency at low fabrication cost was realized. A 2 × 2 dual circularly polarized (CP) antenna subarray was firstly designed to suit for the 5G mmW new radio (NR) of 24.75 to 27.5 GHz with polarization diversity. A 4 × 4 dual CP array was finally accomplished using the subarrays as the basic building blocks. The full-corporate waveguide technology was employed to reduce the antenna weight and transmission loss but enhance the isolation for dual CP operation. Measured results validated the proposed design and showed that a wide operating bandwidth of 13% (24.4–27.8 GHz) with peak gain of 21 dBic and an isolation of better than 15 dB were achieved. Moreover, a high radiation efficiency (95%) and a medium aperture efficiency (53%) were attained by the dual CP array. The advantages of low cost, low loss, and flexible fabrication make the 3D-printed antenna array be outstanding.

A single fed wideband mode‐reconfigurable OAM metasurface CP antenna array with simple feeding scheme

In this paper, a low-profile mode reconfigurable orbital angular momentum (OAM) circular polarization (CP) array antenna is presented, which consists of 2 × 2 elements and a single feed network. Each element is a metasurface subarray composed of 4 × 4 square patchs. The vias in the subarray produces 90° phase difference between x- and y- polarizations, and CP is realized. Both the 90° phase-shifting reconfigurable feed network and broadband 180° phase shift by the mirror images are used to generate the OAM helical phase. The OAM modes l can be dynamically switched between l = +1 and l = −1 by controlling operation states of p-i-n diodes in the feed network. The CP and OAM impedance bandwidths are 13.3% (from 5.8 to 6.6 GHz). The peak gains for the two modes are 9.4 dBi. The developed array antenna has the following advantages of the least pin diode number, high gain, small size, lowest divergence angle, wideband CP, low cross-polarization and low fabrication cost. Therefore, the proposed antenna is very promising for modern high-speed and large capacity wireless communication systems.

Dual Circularly Polarized Array Antenna Based on Corporate Feeding Network in Square Waveguide Technology

In this communication, the design and fabrication of a Ku -band antenna array is presented for dual circular polarization, using a corporate feeding network (CFN) with orthogonal dual-mode operation. A four-way CFN in square waveguide technology is implemented to uniformly illuminate the antenna array. Each of the two propagating modes in the square waveguide excites orthogonal polarizations in the antenna. A dual circularly polarized radiating element is used for the dual-polarized array. Consequently, the link capacity can be doubled by using orthogonal polarizations in a compact and low-loss antenna system. Prototypes have been fabricated by conventional machining and they have been experimentally tested. A 90% total efficiency and matching coefficient better than −10 dB have been obtained in the frequency band between 16.5 and 17.5 GHz for the dual circularly polarized antenna. Further simulations have proven the validity of this topology for larger dual-polarized planar arrays.

Wideband and high-gain circularly-polarized L-shaped slot antenna array using metamaterial

AbstractThis research involves a compact wideband circularly-polarized antenna array, which consists of a sequential rotating phase feed network, 2 × 2 mushroom-type metamaterial (MTM) unit, and so on. Each antenna array unit contains a microstrip feedline, an L-shaped slot antenna, and so on. The MTM-based antennas were incorporated with a sequential-phase network of sequentially rotated series-parallel feed to achieve wideband operation. The operational bandwidth and the radiation model in the high-frequency area were improved through the adjustment of spacing between the L-shaped slots while maintaining the size and structure of the MTM. The proposed design had dimensions of 80 mm × 80 mm × 3.5 mm (~1.64 λ0 × 1.64 λ0 × 0.072 λ0 at 6.15 GHz), and it was simulated, fabricated, and tested.

A Reconfigurable Antenna With Sum and Difference Patterns for WLAN Access Points

This letter presents a reconfigurable antenna with sum and difference patterns for the applications of wireless local area network (WLAN) access points. The proposed antenna consists of a 2 × 2 circularly polarized (CP) stacked-patch antenna array and a switchable monopulse comparator network. Utilizing this comparator network to excite the CP antenna array, sum, azimuth difference, elevation difference, and bidifference beams are produced and can be switched by controlling the dc voltages on the p-i-n diodes. Measurement reveals that the antenna's return loss is better than 10 dB in the frequency ranges of 2.26–2.58 GHz, 2.24–2.62 GHz, 2.25–2.61 GHz, and 2–3 GHz at the sum, azimuth difference, elevation difference, and bidifference modes, respectively. The measured axial ratios, gains, and radiation patterns also show that this antenna can be applied to enhance the communication-area coverage capability for WLAN access points.

Performance Enhancement of Array Antennas using Metasurface Superstrates

AbstractThis work presents a novel design of a high gain circularly polarized (CP) crossed‐bowtie shaped antenna with cloverleaf arms which exhibits a wideband impedance match as well as 3dB axial ratio bandwidths. The designed wideband antenna is realized by employing a low‐cost phase shifting mechanism that uses a Metasurface (MTS) superstrate which is placed above the radiating surface of the antenna. A design chart is developed for the determination of the required phase variation based on the distance between MTS and the antenna radiator. Next, the concept of MTS placement above the antennas is extended to the cases of 3x3 and 5x5 cloverleaf‐shaped bowtie antenna arrays, with the goal of improving the gain and sidelobe levels (SLLs). The study includes a systematic analysis of the variation in gain and SLL of CP antenna arrays as we change the number of elements of the superstrate.

8 × 2-Element 60-GHz-Band Circularly Polarized Post-Wall Waveguide Slot Array Antenna Loaded With Dipoles

In this paper, an 8 × 2-element 60-GHz band circularly polarized post-wall waveguide slot array antenna loaded with dipoles is proposed. The antenna is composed of a feeding circuit, radiating slots on radiating waveguides, and dipoles for polarization conversion. By integrating the feeding circuit and the radiating waveguides into a single dielectric layer, the total number of dielectric layers is reduced to two which greatly increases ease of mass production. The feeding circuit divides power into two and feeds the two radiating waveguides from their center. 8 × 2 radiating elements are composed of a slot and a dipole placed on the radiating waveguides. The elements are designed by standing-wave excitation. The antenna is fabricated by printed circuit board technology and its dimensions are 44.5 × 20.0 × 2.16 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . The measured results show a 2.1-dB axial ratio, 15.6-dBi gain, and 57.2% efficiency at 61.5 GHz. The proposed antenna realizes a circular polarized array antenna with the minimum number of dielectric layers and electric performance comparable to conventional antennas.

Simulation and Calculation of Sum Beam Feeding Phase in 8-Element Sequential Rotating Circularly Polarized Antenna Array

Abstract The beam forming network is a key component of the realization and difference function of the single-pulse antenna array. Obtaining the amplitude and phase information of each port of the network is the premise of designing the beam forming network. This paper gives and calculates the feed phase expression of the generated and beam in the 8-element sequential rotating circularly polarized antenna array. The circular polarization components and axial ratio characteristics of the φ=0°, φ=45° and φ=90° planes are calculated by left-hand and port feeding. The results show that the pure circularly polarized wave is obtained in the direction of θ=0° when the φ=0° surface is left-handed and the port is fed. The circular polarization of the antenna is good when the angle is smaller than θ=0°. It shows that the antenna unit obtains a circularly polarized wave after adopting the sequential rotation technique; the circular polarization characteristic on the φ=45° plane and the φ=90° plane is consistent with the φ=0° plane.

W-Band LTCC Circularly Polarized Antenna Array With Mixed U-Type Substrate Integrated Waveguide and Ridge Gap Waveguide Feeding Networks

In this letter, a low-temperature co-fired ceramic (LTCC) substrate integrated 8 × 8 circularly polarized (CP) antenna array is proposed for the wideband and high-gain W-band antenna-in-package application. By introducing the planar L-probe together with the original coupling probe, the E-fields in the substrate-integrated-waveguide (SIW) cavity are changed, and additional E-field components with a 90° phase difference are produced. Then, a CP antenna array is obtained. To reduce the losses in the feeding network, the gap waveguide technology is utilized with the SIW technology, as a mixed feeding network. To validate the proposed CP antenna array design, an 8 × 8 CP antenna array is fabricated by the LTCC technology and measured. Measured results show that the LTCC CP antenna array obtains a gain of 22.3 dBi, and its axial-ratio (AR) bandwidth is from 89 to 98.5 GHz for AR <; 3 dB. Besides, good agreements of the radiation patterns between the simulations and measurements are achieved within the operational frequency range.

Dual-Band Dual Circularly Polarized Antenna Array Using FSS-Integrated Polarization Rotation AMC Ground for Vehicle Satellite Communications

This paper presents a new dual-band dual circularly polarized (CP) high gain patch antenna array for vehicle satellite communications. The array consists of 16 linearly polarized dual-band elements backed with a new frequency-selective-surface (FSS)-integrated polarization rotation ground. The polarization rotation ground is located underneath the array, which not only acts as a reflector to increase the array boresight gain but also enables the array's dual CP radiation. The electromagnetic (EM) waves reflected by the ground retard either 90° or 270° with respect to the EM waves of the array directly radiated to the upper sphere at two frequency bands, leading to the dual-band dual CP radiation. This is totally different from many of the former counterparts which are based on either the perturbation on the stacked patch or external feeding network. Measured results show the −10-dB impedance bandwidth is from 7.8 to more than 8.5-GHz for X-band and from 14 to 15.3-GHz for Ku-band. The 3-dB axial ratio bandwidth is from 8.15 to 8.35-GHz for the lower band (right-hand CP) and from 14.2 to 14.8-GHz for the higher band (left-hand CP), respectively.

Shaped-Beam Circularly Polarized Antenna Array of Linear Elements for Satellite and SAR Applications

A circularly polarized planar antenna array consisting of linearly polarized elements is proposed for satellite and synthetic aperture radar applications. The individual linearly polarized elements are arranged in a linear or planar array form with the feed relations of the elements is adjusted to produce circularly polarized radiation. A subarray element of four λ/2 dipoles arranged in a planar cross form is proposed as a sub-element of the high gain arrays. Ten of these subarrays are arranged in a linear form to produce high gain circularly polarized radiation. The particle swarm optimization algorithm has been used in a new manner to reduce the computation time and producing reasonable results at the same time. This has been implemented by applying the PSO algorithm on two perpendicular linear arrays of point sources, without the need to apply the PSO to calculate the amplitudes and phases for the entire elements of the planar array. For 10 × 10 subarray elements arranged in a square planar form, an isoflux beam is generated in the range plane to realize 16° beamwidth radiation pattern with circular polarization. Also, another planar array of a cosecant squared beam is produced using the same array size in the range plane. The beam is flat-topped in the other perpendicular azimuth plane for both the isoflux and cosecant-squared shaped beams.

A Wideband Circularly Polarized Array Antenna With Compact and High-Efficiency Feeding Network

A wideband circularly polarized (CP) waveguide array antenna is proposed in this article. The proposed array antenna consists of four antipodally ridged elements and a compact feeding network with two orthogonal septa inserted to a stepped cavity. Both the components are wideband and they can work independently or together. The proposed topology gives a good solution to feed a $2 \times 2$ waveguide subarray which is the basis of large-scale arrays. It exhibits a larger working bandwidth than the array antennas fed by high-order mode cavities. A prototype is fabricated using 3-D printing and milling technologies. Measured results demonstrate a bandwidth of 40.3% from 9.9 to 14.9 GHz, in terms of the reflection coefficients less than −15 dB and the axial ratios smaller than 3 dB. An expanded $8 \times 8$ CP array antenna is explored based on the proposed $2 \times 2$ subarray to show the potentials of our design, and a total efficiency over 78% within a bandwidth of 38.7% is obtained by simulation.