A novel reflectarray (RA) with ultra-low-profile and 2-bit phase quantization beam-steering ability is presented in this paper. To reduce the profile, a Leaky-wave feed is used to excite the RA with enhanced illumination efficiency. Moreover, simultaneous sum and difference patterns are also obtained to provide beam flexibility. The entire thickness of the proposed RA is less than 3% of that of the conventional front-fed RA with the same aperture. To increase the efficiency of the RA, a novel unit cell consisting of a polarizer layer and a reflection layer is developed, which is configured to provide polarization rotation and 2-bit phase shifts by using a hybrid of tunable polarization and discrete resonator. The operation principle, theoretical explanation, and implementation of the proposed antenna are elaborated in this work. To prove the design concept and beam scanning performance, an array with 9×7 unit cells operating at Ka-band is designed and simulated firstly. 2-D beam scanning within the range of ±30º has been verified. Then, a passive prototype with 9×67 unit cells is designed, fabricated and measured. Experimental results show aperture efficiency of 35.1% and illumination efficiency of 43.4%. The developed RA is scalable, and it provides a viable low-cost solution to develop low-profile, high-gain and beam-steering array antennas for satellite applications.
A highly integrated K/Ka-band phased array with duplexing channels for transmitting and dual circularly polarized channels for receiving is presented. To increase both the efficiency and channel isolation, a novel architecture is proposed to integrate the horn antenna, polarizer, ortho-mode transducer (OMT), and filters within a very compact radiating aperture as the element. Based on this element, one large-scale phased array with 416 elements was developed, fabricated, and measured. Experimental results show that the proposed phased array has high aperture efficiency of larger than 56% in both transmitting and receiving channels, high channel isolations of 50 dB between different frequency channels and 20 dB between different polarization channels. Furthermore, beam scanning performance within ±20 and ±18 at 20 and 30 GHz are achieved, respectively. The developed multifunctional phased array is an attractive and feasible frontend for K-/Ka-band SatCom system.
K E Y W O R D Sdual-band, high channel isolation, multi-channel, satellite phased array
The depolarization effect of carbon‐fiber reinforced plastics (CFRP) reflector is studied and a cross‐polarization discrimination (XPD) compensated method for dual‐reflector antenna without metallizing reflectors is presented in the paper. By setting the fibers direction of the main reflector orthogonal to that of the subreflector, the phase difference of the reflected electric field components from the first‐ and second‐layer of the CFPR sandwich can be compensated and depolarization effect would not happen. A dual‐reflector antenna operating at Ku band is designed, simulated and measured. The measured XPD of both the compensated and uncompensated designs are compared, and results show that XPD improves more than 3.0 dB. This method is a valid and low‐cost solution for dual‐reflector antennas in circular polarization to pursue excellent XPD performance, which is highly suitable for satellite larger‐aperture CFRP reflector antennas.
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