Dual Circularly Polarized Antenna Research Articles

Ultra-Wideband Dual-Circularly Polarized Crossed-Dipole Antenna With Stripline Coupler and Parasitic Elements for Vehicular Sensing and Communications

Ultra-Wideband Dual-Circularly Polarized Crossed-Dipole Antenna With Stripline Coupler and Parasitic Elements for Vehicular Sensing and Communications

Ultrathin Single Layer Transmissive Dual-Band Linear to Circular Converter for Non-Adjacent Dual Orthogonal Circularly Polarized Antenna

Ultrathin Single Layer Transmissive Dual-Band Linear to Circular Converter for Non-Adjacent Dual Orthogonal Circularly Polarized Antenna

Dual Circularly Polarized and Linearly Sweeping Leaky-Wave Antenna

Dual Circularly Polarized and Linearly Sweeping Leaky-Wave Antenna

High-Gain Dual-Circularly Polarized Leaky-Wave Antenna for Point-to-Point Communications

In this letter, a high-gain low-profile dual-circularly polarized (CP) leaky-wave antenna (LWA) with fixed beam is presented. The proposed LWA comprises only two-layered substrates, in which the top layer constructs the annular LWA array while the bottom layer realizes the feeding network. To obtain the fixed beam, the differential excitation generated by the proposed coupler is employed. Furthermore, the dual-CP feeding network provides two sequentially rotated phase excitations for the slot coupler, then the dual-CP radiation with fixed beam is realized. The profile height of the proposal is only 0.15 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> at 28 GHz, while the measured peak gain is up to 27.2 dBic; this could be attractive for point-to-point communications.

Simple Dual-Feed Dual-Circular Polarization Antenna with High Isolation

A dual-feed antenna system with circular polarization (CP) diversity and high isolation is proposed in this paper. The proposed antenna consists of two bent monopole antennas and an isosceles triangular partial GND on a single layer. To simply design an antenna with dual-feed dual-CP characteristics, CP bandwidth (BW) is optimized based on a single antenna. The proposed antenna is structurally different from conventional antennas in three ways. Structural asymmetry is realized by bending the shape of the antenna and moving the position, and thus good CP characteristics are obtained. The feeding structure is changed from a linear type to a meander type. As a result, a single monopole antenna has a CP BW of 36%. Next, an antenna system with dual-CP characteristics is introduced by implementing two monopole antennas on a single layer. In this structure, the resonant frequency is controlled by the antenna geometrical parameters, and the null frequency at S21 is controlled by the distance between the two antennas. The measured results show that the CP BW of the proposed antenna is 40.6% (1.51–2.28 GHz). The measured isolation is below -20 dB within the operating BW.

Three-Dimensional Printed, Dual-Band, Dual-Circularly Polarized Antenna Array Using Gap Waveguide Technology

A gap waveguide (GW)-based 4 × 4 dual-band, dual-circularly polarized antenna array is proposed. The antenna is composed of two stacked layers which are responsible for right-handed circularly polarized (RHCP) radiation in K-band and left-handed circularly polarized (LHCP) radiation in Ka-band. Each stacked layer consists of a GW power distribution network to excite 16 radiating units from a single input. A waffle grid is mounted on top of the array structure to increase effective aperture areas and reduce grating lobes. A prototype was fabricated using stereo lithography appearance (SLA) 3D printing and metallization technology, which significantly decreased the fabrication cost and complexity. Measurement results for the antenna prototype demonstrate the operating bandwidths of 19.91–20.52 GHz in K-band and 28.26–29.19 GHz in Ka-band, over which the reflection coefficients of &lt;−10 dB and axial ratios of &lt;3 dB are achieved. The prototype provides peak gains of 20.1 and 20.3 dB with total efficiencies of &gt;90% in the two respective bands. The combination of dual-band, dual-circularly polarized capability, high gain, high efficiency, lightweight, low cost and compact size renders the proposed design a potential candidate for commercial millimeter wave communication applications.

A Wideband Endfire Dual Circularly Polarized Antenna for 5G Millimeter-Wave Applications

In this letter, an all-metallized wideband dual circularly polarized antenna with endfire radiation is proposed for fifth-generation (5G) millimeter-wave applications. By introducing two rectangular notches on the side walls of open-ended waveguide, the vertical components are increased and close to the horizontal components in the broadband range so that the axial ratio (AR) bandwidth is enhanced. The simulated results show that the proposed antenna excited by wave port has 63.9% operation bandwidth (22.7–44.0 GHz), where reflection coefficients less than −10 dB, isolations greater than 20 dB, and AR less than 3 dB are achieved. To verify the design, the proposed antenna excited by coaxial connectors is fabricated and measured. Based on the measurement results, the reflection coefficients less than −10 dB, isolations greater than 20 dB, and AR less than 3 dB are achieved from 23.0–40.0 GHz, the endfire gain varies from 5.1 to 8.5 dBic at the frequencies mentioned above.

A Tunable Dual-Circularly Polarized Antenna With Broadband Triple-Branched Feed Structure

A novel reconfigurable circularly polarized (CP) patch antenna with tunable operation band and switchable polarization states is proposed. Four varactors are placed symmetrically across the cross-shaped slot on the upper square patch so that the operation band of the proposed antenna can be continuously controlled through the specially designed bias. Meanwhile, a triple-branched broadband switchable feed structure loaded with p-i-n diodes is specially designed to achieve polarization reconfigurability (LHCP, RHCP). The structure novelly integrated a 180 <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> broadband phase shifter with a 90 <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> one by a shared reference branch. Simulation results of the feed structure exhibit stable phase-shift in a wide bandwidth of 58.7 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\%$</tex-math></inline-formula> under <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\pm 5^{\circ }$</tex-math></inline-formula> phase imbalance. A prototype of the antenna is fabricated while both measured and simulated results agree well. The antenna achieves good impedance matching from 2 to 2.7 GHz and the axial ratios at both polarization states are smaller than 3 dB. The frequency and polarization reconfigurability make the antenna potentially suitable for satellite applications, such as multifrequency satellite data link transceiver.

Electromagnetic Performance of Waveguide Polarizers with Sizes Obtained by Single-Mode Technique and by Trust Region Optimization

Modern wireless networks, stationary terrestrial and satellite systems use many modern technologies to increase communication channels information capacity. They save limited frequency resources. In satellite communications the polarization signal processing is applied to reuse the allocated frequency bands. Usage of circularly polarized electromagnetic waves, which transmit useful signals, reduces fading effects and eliminates disadvantages introduced by multipath propagation interferences. In this case the distortion levels for signals with an odd number of electromagnetic waves reflections in the receiving antenna systems will be reduced down to the thresholds of their cross-polarization isolation. Besides, in the case of orthogonal polarizations usage, the achieved information capacity of the applied wireless communication channel multiples almost by the factor of two. The type of polarization of the used electromagnetic wave strongly determinates the peculiarities of the process of its propagation in the space or transmission line. Polarization signal processing is frequently carried out in horn feed systems of the reflector antennas. Such feed networks and systems allow to transmit and receive signals with several kinds of polarization at the same time. The fundamental element of dual circular polarization antenna feed networks is a waveguide polarization duplexer. The phase, isolation and matching characteristics of a polarization converter strongly influence on the functionality and polarization discrimination possibilities of the entire reflector antenna system. Therefore, the development and optimization of the characteristics of waveguide polarizers for satellite communication antennas is a crucial technical problem, which must be solved by fast and accurate methods. The comparison of electromagnetic performance of waveguide polarizers with sizes obtained using a fast single-mode technique and by more accurate trust region optimization method is carried out in this research. The results for differential phase shift, level of voltage standing wave ratio, ellipticity coefficient and cross-polarization discrimination are shown and discussed.

A Portable 5.8 GHz Dual Circularly Polarized Interferometric Radar Sensor for Short-Range Motion Sensing

The conventional short-range interferometric radar sensors usually employ two separate transmitting (TX) and receiving (RX) antennas for improved TX–RX isolation. However, they are subject to increased system size and misalignment of the TX/RX radiation patterns. In this article, a portable 5.8 GHz dual circularly polarized (CP) interferometric radar sensor is presented, which leverages the proposed dual CP common-aperture antenna that reduces the size of the entire radar system. The common-aperture nature gets rid of the radiation pattern misalignment and ensures that the object can be in the optimal boresight direction. Cross polarization, i.e., right-hand CP (RHCP) for TX and left-hand CP (LHCP) for RX or vice versa, was employed based on the sequentially rotated array (SRA), which not only improves the TX–RX isolation but also adapts with the polarization change in radar sensing. Moreover, a near-field cancellation technique was proposed to further increase the TX–RX isolation in the small form factor. A portable 5.8 GHz radar sensor integrated with the proposed dual CP antenna was custom-designed. Compared to the conventional two-antenna architecture, the proposed radar sensor is reduced in size by 140% but can still achieve a high TX–RX isolation of >60 dB at 5.8 GHz. Experiments were carried and the results illustrate that the proposed radar sensor has high micrometer accuracy in detecting the predefined displacement motions and is able to precisely track the human vital signs in the office environment.

Single Layer Dual Circularly Polarized Antenna Array Based on Ridge Gap Waveguide for 77 GHz Automotive Radar

A single layer 77 GHz dual circularly polarized (CP) antenna array is proposed based on ridge gap waveguides (RGWs) technology. The antenna consists of eight U-shaped slots, fed by two feeding networks for generation of dual CP. The proposed antenna array has been fabricated and measured. The experimental results show good agreement with the simulations. The axial ratio is below 2 dB, and the return loss and port isolation are better than 13 and 18.6 dB over 76–81 GHz, respectively. The measured gain for the integrated array is 14.8 dBi at the center frequency of 78.5 GHz. With integration of feeding networks and the radiating elements in a single layer, this antenna has potential to be used in automotive radars.

High‐Gain Dual Circularly Polarized Antenna for Air‐to‐Ground Wireless Link

High‐Gain Dual Circularly Polarized Antenna for Air‐to‐Ground Wireless Link

Novel series fed dual band circular polarization antenna for navigational satellite system

A novel series fed dual band stacked microstrip patch antenna (SMPA) offering circular polarization (CP) over wide beam is proposed for Indian regional navigation satellite system (IRNSS). The antenna is designed to function at far apart dual frequencies 1.176 GHz (L5 band) and 2.492 GHz (S band) intended for the receiver terminals of IRNSS system. The dual band performance with large frequency ratio (about 1:2.1) has been obtained by two stacked patches with an air layer between them. The square notches at the corners along the diagonal of lower square patch, one sided corner truncation along the diagonal of upper square patch and feeding along central axis is used to obtain CP (with axial ratio &lt; 2) at both the operating bands. The square patches are excited with novel series feed technique. The proposed novel antenna has been designed, simulated and developed to meet the stringent design requirements for IRNSS navigation system. The antenna has achieved an impedance bandwidth of 2.6% and 2.2% at L5 and S band frequency respectively. It possesses positive gain beamwidth of 120and 3 dB axial ratio beamwidth of 120 ◦ and 60 ◦ at L5 and S band frequencies respectively.

A Ku-band Low-profile Dual Circularly Polarized Antenna Based On QMSIW

A Ku-band Low-profile Dual Circularly Polarized Antenna Based On QMSIW

새로운 6-단자 급전 회로망을 이용한 이중 직교 원형 편파를 갖는 소형 고이득 GPS 안테나

In this study, the design, fabrication, and performance of a small high-gain global positioning system (GPS) antenna that generates dual orthogonal circular polarization using a novel six-terminal feeding network is presented. The proposed six-terminal feeding network has two input quadrature terminals and four output terminals having the same amplitude and 0° or 180° phase. Therefore, it is suitable for feeding the four radiating elements with linear polarization characteristics. To realize a dual orthogonal circular polarization antenna with miniaturization and high gain characteristics, the six-terminal power supply network is positioned in the center of the antenna, and the four radiating elements are arranged on the outside. The radiating element selected after considering the limited space is a three-dimensional printed dipole element with linear polarization characteristics which is rotated by 90°. The antenna size designed optimally in the GPS L1 band (1,575.42±12 MHz) is less than 130 mm (0.68 λ0) in diameter (D) and 40 mm (0.21 λ0) in height. The antenna’s input return loss and port isolation characteristics measured with a vector network analyzer are excellent within the band at 17.1 dB and 18.0 dB or more, respectively. In addition, the antenna gain, and efficiency measured in the anechoic chamber are 8.69 dBi (@bore-sight) or more and 83 % or more, respectively. Furthermore, it can be seen that the axial ratio characteristics of the dual orthogonal circular polarization wave are very good, with less than 0.2 dB (@bore-sight) and less than 1.8 dB (@ 3 dB beam width).

Wideband Dual Circularly Polarized Antenna for Intelligent Transport Systems

A wideband dual circularly polarized (DCP) antenna is presented for intelligent transport system (ITS) applications, which can be used to improve the receiver sensitivity and communication quality of ITS. The presented DCP antenna is composed of an orthogonal power divider (OPD) with two orthogonal input ports, four phase shifters for quadrature phase output, and four crossed dipoles for DCP radiation. Detailed equivalent circuit analysis shows that the OPD has two orthogonal inputs and four equal magnitude in-phase and out-of-phase outputs. To achieve two sets of orthogonal quadrature output signals for DCP radiation, the lumped element based differential right-hand transmission line unit cell and left-hand transmission line unit cell are elaborately introduced as the ±45° phase shifters, and incorporated into the OPD. Eventually, orthogonal quadrature signals are successfully obtained and fed to the crossed dipoles for DCP radiation. The proposed antenna was then designed, fabricated, and measured for ITS applications. The measured results show that the overlapped impedance bandwidth of both two input ports is 1.07–1.85 GHz (53.4%), and the isolation is higher than 15.2 dB. Moreover, low axial ratio (<1.7 dB) and symmetrical radiation patterns are achieved for unidirectional DCP radiation.

Design of a Compact Dual Circular-Polarized Antenna for L-Band Satellite Applications

In this letter, we propose a design of a dual circular-polarized antenna for L-band applications (1.1–1.6 GHz). The designed antenna has been developed by considering crossed-dipoles on top of which a circular patch has been placed, to properly act on the mutual coupling between the dipoles. The dual circular polarization is achieved by feeding dipoles in quadrature. Moreover, to increase the antenna gain and polarization purity at high elevation angles, a fence of passive monopoles has been added. The proposed antenna can profitably used as primary feed of a low-frequency parabolic reflector.

A Compact Hollow Dual Circularly Polarized Antenna With Folded Coupled Feed Structure for Distance Detection Application

A wideband and dual circular polarization hollow patch antenna fed by a tapered fold coupled structure is presented for distance detection application. The proposed antenna consists of a gear-shaped ring radiation patch etched on a three-layer dielectric substrate, four tapered folded feedlines, a ring ground plane and a feeding network. To achieve right-handed circular polarization (RHCP) and left-handed circular polarization (LHCP) characteristics, four hybrids are employed. The proposed hollow antenna can be seamlessly integrated and installed under the cover of sharp shaped aerobat without effect on its flight characteristics. As a proof-of-concept, an antenna working at 1.8 GHz is prototyped and tested. The measured and simulated results show that the proposed antenna exhibits a wide impedance bandwidth of 270 MHz (1.695 - 1.965 GHz) and a wide 3-dB axial ratio (AR) beamwidth of 140 degree.

A Compact Dual Circularly Polarized Antenna With Wideband Operation and High Isolation

This paper presents a dual-sense circularly polarized (CP) antenna with compact size, high isolation, and wideband characteristics. The antenna consists of a microstrip patch, an array of parasitic metal plates positioned around the patch, and a 90° branch line coupler as feeding structure. Unlike the conventional design method, we demonstrate that the wide isolation bandwidth can be achieved with an imperfect coupler and imperfect matching at the radiating element. The final design with overall dimensions of $0.59\lambda _{c} \times 0.59\lambda _{c} \times 0.06\lambda _{c}$ ( $\lambda _{c}$ is the free-space wavelength at center operating frequency) was fabricated and tested. Measurements on the fabricated prototype show that the antenna has a bandwidth of 16.5% (5.0–5.9 GHz) with port isolation of better than 15 dB. In addition, a peak broadside gain of about 6.6 dBic is attained. In comparison with other related works in literature, this antenna has advantages of wide operating bandwidth with high isolation while possessing a compact footprint.

Miniaturized Circularly Polarized Doppler Radar for Human Vital Sign Detection

In this paper, a miniaturized circularly polarized (CP) continuous wave Doppler radar system operating at 2.4 GHz is presented. The radar front end consists of one left-handed CP (LHCP) antenna and one right-handed CP (RHCP) antenna, which share a single patch antenna aperture. Orthogonal polarization is achieved through a modified ring-shaped quadrature hybrid coupler (QHC), and the resulting isolation between the two CP antennas is better than 30 dB. With 0 dBm input power to the transmitting antenna, the proposed radar system can accurately detect heartbeat and respiration movements of human test subjects under 1 m and over a wide angular range. The single dual CP antenna achieves 280% size reduction compared to a traditional two linear polarization patch antenna array with the same isolation level.