A broadband and wide-angle scanning linear polarization (LP)-to-circular polarization (CP) converter based on a dual-layer structure is presented. The elementary cell is composed of conventional Jerusalem crosses (JCs). The design procedure is based on transmission line circuit model and on full-wave simulations. The proposed equivalent circuit has been generalized to include the oblique incidence in the model. Simulated results demonstrate a 24% axial ratio bandwidth for an incidence angle $\theta = \pm 50^{\circ }$ in both x z and y z planes. The proposed converter provides a unique combination of wide bandwidth, thin profile, and stable response with respect to the angle of incidence. It can be integrated into any LP antenna system to generate CP without significantly affecting the antenna performances.

A Broadband, Wide-Angle Scanning, Linear-to-Circular Polarization Converter Based on Standard Jerusalem Cross Frequency Selective Surfaces

Antenna arrays have potential applications in Radar, mobile, broadcasting, astronomy and other defense and commercial platforms. The design of antenna arrays is essential as they are capable of controlling the radiation pattern in terms of sidelobe level (SLL), beamwidth (BW), nulls and beam steering. Among several geometries of antenna arrays, the circular antenna arrays have the advantage in terms of inherent capability to control the phase implicitly. In this paper, circular antenna array synthesis is presented using novel metaheuristic techniques like the Social Group Optimization Algorithm (SGOA) and Modified SGOA (MSGOA). The main objective of the synthesis process is to synthesize radiation patterns with suppressed SLL while the BW being equal to the uniform distribution. A comparative study is performed to analyze the performance of various synthesis techniques like amplitude only, inter-element spacing only, and amplitude spacing. The MGSOA and SGOA have proved to be performing well in accomplishing the objective. Further, the CAA synthesis problem is translated into single-variable and multivariable optimization problems following which the obvious advantage associated with the inclusion of additional variable as an additional degree of freedom is demonstrated. The simulation is carried out in Matlab®, and results are analyzed using the plotted radiation patterns.

Circular antenna array optimization using modified social group optimization algorithm

A dual-band linear-to-circular planar polarization converter based on a multilayer printed circuit board (PCB) is proposed and demonstrated. Each cell of the periodic surface is formed by six substrate layers separated by five foam spacers. The three top layers are identical and contain an ‘I’-type strip, while the three layers on the bottom side are realized with three identical Jerusalem crosses (JC). A linearly polarized (LP) wave tilted 45° relative to the x- and y-axis of the converter is used to illuminate the polarizer. In this configuration, right-handed circularly polarized (RHCP) waves are generated at the Ka-band while left-handed circularly polarized (LHCP) waves are generated at the K-band. An equivalent circuit model based on transmission lines is proposed and used to design the polarizer together with full-wave simulations. The simulated/measured axial ratio (AR) remains below 3 dB in the bands 19.4–21.8 GHz (12.5%) and 27.9–30.5 GHz (8.7%) with an insertion loss better than 0.5 dB.

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Dual-Frequency Linear-to-Circular Polarization Converter for Ka-Band Applications

A 3-D-printed dielectric lens is proposed in this paper to widen the 3-dB axial-ratio beamwidth (ARBW) of conventional circularly polarized (CP) patch antenna. The proposed lens is constructed by a solid dielectric cylinder with a cone-shaped air cavity. To illustrate the working principle, the geometric optics method is introduced, then refractions of the CP wave caused by the lens are theoretically analyzed and the related equations of axial ratio (AR) are derived. Besides, the key parameters that affect the ARBW of the CP antenna are adequately investigated, and the general rules are summarized to design it conveniently. To provide two orthogonal modes at center frequency, a dual-feed network is used to drive the patch antenna. To demonstrate, prototypes with and without lens are designed, fabricated, and measured. The experimental results show a good agreement with the simulated ones in terms of returned loss, radiation pattern, gain, and AR. The measured 15-dB impedance bandwidth is 20.4%, the 3-dB AR bandwidth is 17.5%, and the peak gain at main radiated direction is 5.5 dBic. Furthermore, the compared results in measurements show that by using the proposed lens, the 3-dB ARBW of CP antenna can be extended effectively from 82° to 162°, which is highly demanded in global navigation satellite system for reducing multipath interference. Finally, the applicability of the proposed lens is discussed including the available frequency bandwidth, the size of ground plane, and the feasibility for other types of CP patch antennas.

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3-D-Printed Dielectric Lens With Cone-Shaped Cavity for Axial Ratio Beamwidth Enhancement of Circularly Polarized Patch Antenna

The invention provides a dual-frequency shared-aperture array antenna. The dual-frequency shared-aperture array antenna comprises a Ku-frequency-band substrate integrated waveguide loaded Dipole antenna, a Ka-frequency-band metal waveguide antenna formed by a substrate integrated waveguide wall and a copper plate, a Ka-frequency-band integrated waveguide feed structure and a Ku-frequency-band substrate integrated waveguide feed structure, wherein a feed network of the Ka-frequency-band substrate integrated waveguide feed structure and the Ku-frequency-band substrate integrated waveguide feed structure is integrated on a same medium substrate. In the dual-frequency shared-aperture array antenna provided by the invention, a substrate integrated waveguide transmission portion of the Ku-frequency-band substrate integrated waveguide loaded Dipole antenna not only forms an antenna of a Ku frequency band, but also serves as a wall of a Ka-frequency-band rectangular metal waveguide together with the copper plate playing a role in fixation, so that the aperture multiplexing is realized, the mutual coupling of the antennas is greatly reduced, the aperture size of the antenna is reduced, andthe dual-frequency shared-aperture array antenna is realized.

Dual-frequency shared-aperture array antenna

The invention discloses a dual-port dual-frequency dual-circular polarized micro-strip array antenna, comprising a dielectric substrate (1), four dual-frequency shared radiation patches (21, 22, 23, 24) arranged on the upper surface of the dielectric substrate (1), a first feeding port (3) and a second feeding port (4), wherein a first-frequency output end of the four radiation patches (21, 22, 23, 24) is connected with the first feeding port (3) through a series-feed power division network (5), and a second-frequency output end of the four radiation patches (21, 22, 23, 24) is connected with the second feeding port (4) through a parallel-feed power division network (6). The dual-port dual-frequency dual-circular polarized micro-strip array antenna disclosed by the invention is simple in structure with a low section plane, good in bandwidth and low in cross polarization, can be expanded into a large-scale array conveniently, and has unique advantages for dual-circular polarization application of two frequency points with close frequencies, and the two ports have good isolation.

Dual-port dual-frequency dual-circular polarized micro-strip array antenna

The invention discloses a high gain dual-frequency dual circularly polarized common-caliber planar array antenna which comprises a radiation array (1), a first frequency power divider (2) and a second frequency power divider (3), wherein the first frequency power divider (2) and the second frequency power divider (3) are respectively connected with the left end and right end of the radiation array (1). The high gain dual-frequency dual circularly polarized common-caliber planar array antenna has good polarization isolation and high frequency isolation.

High gain dual-frequency dual circularly polarized common-caliber planar array antenna

An improved measurement method of circularly-polarized (CP) antennas based on linear-component amplitudes is proposed in this paper. By utilizing two sets of orthogonal linear polarization (LP) amplitudes, measurement on axial ratio (AR) of CP antennas can be realized without phase information. However, the rotation sense of the co-polarization cannot be determined due to the absence of the phase information. Above problem is discussed here for the first time, and a solution is presented to determine the rotation sense of the co-polarization by using common auxiliary CP antennas. In addition, there will be some particular cases with large errors in actual measurement. Here a corresponding solution method is given. Finally, co-polarization and cross-polarization patterns can be further obtained from AR results. To verify this improved method, a self-developed CP microstrip array was measured. The measured results are in agreement with the simulated results, which prove this method is correct, effective and practical.

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Improved Measurement Method of Circularly-Polarized Antennas Based on Linear-Component Amplitudes

A novel circularly polarized (CP) microstrip antenna with wide beam and high front-to-back ratio is proposed for compass navigation satellite system (CNSS) application. Based on the single-fed patch antenna, parasitic strips are loaded on the same layer to broad the beamwidth. Reactive impedance structure (RIS) is designed as a reflector to obtain a high front-to-back ratio. More importantly, good circularly polarized performance can be obtained in a wider range of beamwidth by adjusting reflection phase. Experimental results show that the measured half-power (HP) beamwidth is approximately 147° and the 3dB axial-ratio (AR) beamwidth is more than 180°. A front-to-back ratio of 20 dB can be achieved within the bandwidth.

Wide-beam circularly polarized microstrip antenna with high front-to-back ratio for CNSS application

A circularly polarized antenna array is proposed by loading a cavity-backed cross-slot antenna over the longitudinal slots on the SIW upper layer in this paper. The longitudinal slots are etched to couple energy to array from SIW. The cavity-backed cross-slot antenna is designed to achieve CP radiation. The radiation unit has good isolation characteristic, which is desirable to design a circularly polarized antenna array. A 1-by-8 circularly polarized array operating at 10 GHz has been developed. Simulated impedance bandwidth of 4.6%, the 3-dB axial ratio bandwidth of 2.1%, the gain of 13.82dB and cross polarization levels of about 24.22dB have been achieved. Moreover, the proposed antenna owns the easy processing and the low profile. It can be conveniently expanded to a larger wideband CP array with a higher gain, which is preferred for the specific satellite communication applications.

Min Wang

Papers

Dual-port dual-frequency dual-circular polarized micro-strip array antenna

High gain dual-frequency dual circularly polarized common-caliber planar array antenna

Improved Measurement Method of Circularly-Polarized Antennas Based on Linear-Component Amplitudes

Wide-beam circularly polarized microstrip antenna with high front-to-back ratio for CNSS application

Circularly polarized cross-slot antenna array fed by substrate integrated waveguide