Wide Beam Circular Polarization Research Articles

Compact Wide-Beam Circularly Polarized End-Fire Antenna Combining Ground Radiation Mode and Vertically Polarized Mode

A compact wide-beam endfire antenna with ground radiation mode and vertically polarized mode for circular polarization (CP) is presented in this article. The antenna is constructed based on a configuration of coupled-mode patch antenna (CMPA), which consists of two coupling cavities with a shorting wall, and can generate vertically polarized modes. The CP is realized through a pair of orthogonally polarized modes of horizontal and vertical polarizations. Meanwhile, rendering them acquires an equal amplitude and a 90° phase difference. The horizontally polarized radiation mode is realized through inserting a crossed ground slot. Offset probe feed is used to excite all the radiation modes and introduce an additional phase shift for the CP. A set of offset ground slots (OGSs) are then applied to perturb the electromagnetic coupling of the modes and adjust the phase and magnitude of the radiating electric fields (E-fields). Several effects are synthesized, which results in a wide-beam circularly polarized (CP) endfire radiation. Aiming to improve the radiation performances, a cavity-backed planar reflector was applied in the experiment. Simulated and measured results are detailed and analyzed, which demonstrate that the measured 3 dB axial ratio (AR < 3 dB) bandwidth (ARBW) ranges from 3.385 to 3.428 GHz (1.2%), and the peak gain can be up to 3.4 dBi if the planar reflector is added. The measured half-power beamwidth (HPBW) and 3 dB ARBW can be up to 88°/114° and 53°/112° at 3.4 GHz, respectively. The antenna size (excluding the reflector) is maintained at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.49\lambda _{0}\times 0.25\lambda _{0}\times 0.017\lambda _{0}$ </tex-math></inline-formula> , where <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{0}$ </tex-math></inline-formula> is the wavelength in free space, performing a compact configuration.

A Novel Design of Flat-Top Beamforming Anti-Multipath Antenna

This article discusses a novel design method of wide-beam circular polarization array antenna for satellite navigation. For special applications such as satellite navigation guiding aircraft landing, high-performance ground reference station antennas are required. In the system of satellite navigation guiding aircraft landing, the antenna of satellite navigation receiver needs to have the following radiation characteristics: the shape of antenna pattern is close to an ideal hemisphere, the upper half of space has uniform right-hand circular polarization gain, and the beam has the characteristic of sharp cutoff below 5 degrees of elevation. Whether the GNSS reference station antenna can have a wider beam circular polarization characteristic to receive more navigation satellites signal; whether it can suppress the multipath effect to a greater extent to reduce the multipath error; and whether it can work in a wider frequency band, so that several major satellite navigation systems work together, the above factors directly affect the satellite navigation and positioning accuracy of the entire system. The beam of this antenna has the following feature: sharp cutoff near the horizon for multipath mitigation at low elevation angles. Comprehensive design thereby accelerates system design. It owns wide beam, good circular polarization characteristics, low elevation angle sharp cutoff, and ultralow sidelobe radiation characteristics that achieve the purpose of receiving satellite navigation signal and multipath. The low sidelobe characteristic of the antenna is beneficial to suppress multipath effect. According to the theoretical knowledge of the symmetrical dipole and the four-arm helical antenna, the simple structure of the symmetrical element is fully utilized, and the printed balun easily realizes the dual-frequency operation of the antenna. Combined with the wide-beam circular polarization characteristic of the four-arm helical antenna structure, the shaped beam array antenna is designed. The wide-beam circularly polarized antenna unit not only covers the frequency band of the satellite navigation system but also satisfies the system performance and key feature requirements of the array antenna for the unit; that is, it satisfies the wide-beam circular polarization characteristics of the upper half space. According to the linear array basic theory and array antenna synthesis theory, Woodward Lawson sampling synthesis algorithm is used to synthesize the array amplitude and phase weights corresponding to the specific antenna pattern required for the Ground-Based Augmentation System (GBAS) engineering. The shaped beam array antenna consists of 21 units, of which 11 antenna units are directly fed, and the feeding ports of the rest are dummy ports. It is an equally spaced array antenna. The spacing between antenna units is close to half wavelength. They are fed according to the value corresponding to the excitation function. The array antenna is simulated by HFSS (High-Frequency Structure Simulator). Compared with traditional satellite navigation antennas, the antenna in this paper has excellent front-to-rear ratio and flat-top beam pattern. The results show that the wide-beam circularly polarized array antenna meets the engineering requirements of GBAS applications and lays the solid foundation for GBAS engineering applications.

A Broadband Wide-Beam Circularly Polarized Antenna Array for Urban Macrocell Base Stations

An eight-element broadband wide-beam circularly polarized (CP) antenna array is developed for mobile wireless communications. The CP antenna element consists of two rectangular loops with gaps for circular polarization and parasitic elements for bandwidth enhancement. A wide beamwidth is achieved in the horizontal plane because the CP antenna elements have a narrow cross section in the plane. The CP antenna array also has higher isolation between antenna elements than a linear polarized (LP) array with the same element space, which is due to the polarization mismatch caused by the currents in the CP antenna elements. The eight-element CP antenna array achieves a bandwidth of 40% (1.7–2.55 GHz) for return loss >15 dB and a bandwidth of 47% (1.67–2.7 GHz) for axial ratio (AR) < 3 dB. The half-power beamwidth and the 3 dB AR beamwidth in the horizontal plane are ~65° ± 8° and approximately 100°, respectively. The antenna gain for the array is about 17 dBi. The CP antenna array is suitable for applications in urban macrocell base stations.

Wide‐angle scanning circular polarization phased array based on polarization rotation technology

A wide-beam circular polarization (CP) antenna and a wide-angle scanning phased array based on novel polarization rotation reflective surface (PRRS) are proposed. The CP wide-beam pattern is obtained by the combination of the radiation wave from the patch antenna and the orthogonal reflected wave from the PRRS with a 90° phase difference. The proposed CP wide-beam antenna obtains the patterns with the 3-dB beamwidth more than 136° and the axial ratio (AR) beamwidth more than 132° in the xoz-plane. Furthermore, an eight-element phased array based on the wide-beam CP antenna element is also developed. The measured results show that the main beam of the array can scan from −65° to 65° with a gain fluctuation less than 3 dB and the ARs at every scanning angle less than 3 dB.

A Compact Broadband and Wide Beam Circularly Polarized Antenna With Shorted Vertical Plates

In this paper, a compact broadband and wide beam circularly polarized (CP) antenna are with novel vertical plate structure is proposed. The antenna is composed of two pairs of crossed dipoles, a slotted ground plane with four vertical right-angle plates and four shorted vertical plates. The shorted vertical plates are introduced to balance the current between the dipoles and the slotted ground. With this structure, the performance of bandwidth and beamwidth is improved significantly, and a good match is achieved. Also, a simple coaxial feed is applied without other feed networks. A prototype is fabricated and measured. The results show that the proposed antenna has a -10 dB impedance bandwidth of 92.6% and a 3 dB axial ratio (AR) of 71.8%. Simultaneously, a half-power beamwidth (HPBW) more than 120° and a 3-dB axial ratio beamwidth (ARBW) more than 100° are achieved within a passband of 62.8%. The antenna patterns are identical and symmetrical within the 120° beam range over the operating frequency. Moreover, the antenna has a compact size of 0.4λ 0 x 0.4λ 0 x 0.15λ 0 .

Wide Beam Circularly Polarized Microstrip Antenna with Parasitic Ring for CNSS Application

Wide Beam Circularly Polarized Microstrip Antenna with Parasitic Ring for CNSS Application

A broadband and wide beam circular polarization LTCC microstrip antenna analysis and design with characteristic modes theory

In this paper, characteristic modes theory was used in analysis and design of a broad axial ratio band circular polarization LTCC microstrip antenna. An ellipse slot couple structure was proposed to take the place of traditional circular slot couple structure for enlarging circular polarization broadband. And the theory of how to improve the axial ratio band was researched in detail by characteristic mode method. The characteristic angle phase difference of two orthogonal characteristic modes and the phase difference of feed line in whole frequencies are the key points in these kind of designs. Finally, the designed broadband axial ratio band circular polarization LTCC microstrip antenna was been successfully implemented, and the experimental results are presented and discussed. Good agreement between simulation and testing was achieved.

A Novel Wide-Beam Circularly Polarized Antenna for SDARS Applications

In this letter, a novel wide-beam circularly polarized (CP) antenna is presented for satellite digital audio radio service (SDARS) band (2320-2345 MHz), intended for application in portable terminals. This new antenna is comprised of four independent radiation units that are axial symmetrical around the center. The radiation unit is miniaturized by using a distributed capacitive load and a short point in its configuration. The antenna is excited by a compact four-way, quadrifilar power splitter, which is implemented by using microstrip phase shifter and couplers. Simulation results match well with the experimental ones, demonstrating a half-power beamwidth (HPBW) of 120°, a 3-dB axial-ratio beamwidth of 180°, and a good match at 2100-2400 MHz. The developed antenna is based on low-cost printed circuit board (PCB) technique and can be easily integrated with other microwave circuits.