Millimeter-Wave Wideband Lens Loaded Circularly Polarized Phased Array Antenna With Limited Field of View

This letter introduces a millimeter-wave wideband circularly polarized (CP) phased array antenna (PAA) with limited field of view, which employs a lens loaded sequentially fed CP 2 x 2 patch subarray as an element. Using the element significantly boosts the aperture size of the PAA, enhancing gain without the need for extra channels and incurring additional costs. However, this augmentation usually results in high grating lobes during beam scanning. To tackle this issue, a lens is added to the element, enabling aperture field adjustment to generate a flat-top active element pattern, effectively suppressing grating lobes. A prototype of a 4 x 4-element PAA is designed and measured. Experimental results demonstrate that the proposed PAA achieves a notable high gain (ranging from 20.1 to 23.7 dBic) with acceptable impedance matching and isolation across the 26-32 GHz range (20.7%). The scanning range spans +/- 15 degrees, with a modest 2 dB gain variation, a -10 dB grating lobe level, and a favorable axial ratio. Compared to its counterparts with a similar number of elements, the proposed PAA achieves a much higher gain while maintaining a low cost.