Sarah M. Dever

A novel flat-panel 8×8 wideband dual circularly polarized electronically-scanned phased array antenna is proposed, which covers the satellite communications bands of 22.55–23.55 GHz and 25.5–27.5 GHz. A circularly polarized stacked microstrip patch antenna is used as the element radiator with a structural modification on the parasitic patch to minimize gain variation. Since the axial ratio (AR) bandwidth of the element radiator is inherently narrow, sequential rotation is employed to yield a wide AR bandwidth while forming the 2×2 subarray, which is then used as a building block to construct the larger 8×8 phased array. The phased array has a simulated scan range of ±51°, ±46° and ±36° at 23 GHz, 24 GHz and 26.5 GHz, respectively, assuming ≤3-dB scan loss and AR. A beamforming network (BFN) is integrated within the stackup of the phased array that comprises a commercially available silicon beamforming chip. This facilitates beam steering through the independent control of the input amplitudes and phases of the individual element radiators. The practical effects of the BFN on the scanning performance of the 8×8 phased array is studied, which is found to slightly degrade the scan ranges. Finally, experiments were performed on the fabricated prototype, and the measured scan data showed good correspondence with their simulated counterparts with >41° and 35° scan ranges (in +θ direction) at 24 GHz and 26.5 GHz, respectively. The corresponding EIRp and G/T of the 8×8 phased array are also estimated through measurements.

In this paper, a wideband (22-28 GHz), polarization reconfigurable, flat panel, 8x8 transmit (Tx)/receive (Rx) phased array antenna (PAA) is proposed. The array offers a realized gain of 22-23 dBi/dBic in the broadside direction and scans to approximately ±50° while maintaining 3dB gain drop/scan loss, low cross-polarized fields, and axial ratio (AR) below 3dB (in case of circular polarization (CP)) over the entire bandwidth within the given scan range. By utilizing the amplitude and phase control mechanism of the Radio Frequency Integrated Circuits (RFICs) employed for the beamforming network (BFN), each single radiating element of the array can work in four polarization cases such as horizontal (X-), vertical (Y-), left-hand circular and right-hand circular polarizations. The single element is a novel stacked patch configuration with L-shaped stubs at the two opposite corners of the driven patch and stubs on radiating edges of both the driven and parasitic patches. The radiator offers a wideband performance in addition to resolving the poor isolation between the two ports, thereby improving the cross-polarized fields and AR over the entire bandwidth. The radiating elements are arranged in a unique way in the array such that the benefit of element mirroring is achieved during the dual linear cases, whereas the benefit of sequential rotation of elements is achieved in dual CP cases, which further improves cross-polarized fields and AR. The simulated results are validated through the measurement results for a fabricated PAA prototype for the scanned radiation patterns for all four polarizations in receive mode, antenna gain-to-noise temperature (G/T) in receive mode, and effective isotropic radiated power (EIRP) in transmit mode.