Millimeter-Wave Phased Array Antenna With High Gain, Low Grating Lobes, and Fewer Phase Shifters via Overlapped Large-Sized Elements

This paper presents a millimeter-wave (mmWave) phased array antenna (PAA) design that reduces the required number of phase shifters while achieving high gain and low grating lobes for both horizontal (HP) and vertical polarization (VP) arrays. The design leverages a novel approach using overlapped large-sized elements (LSEs), each comprising a driven subelement with multiple passive and parasitic subelements, all implemented as patches. By configuring the LSEs with tailored aperture fields that approximate a sinc function distribution, the array achieves a flat-top active element pattern (AEP), effectively reducing scan loss and suppressing grating lobes. To demonstrate, 24-GHz 1×5-element HP and VP linear PAAs with λ0 element spacing are developed, which further form 1-D scanning 4×5-element HP and VP planar PAAs, respectively, fed by just five phase-shifted ports. The measurements show that the HP/VP array achieves a peak gain of 22 dBi/21.7 dBi with a scanning range of ±20°/±18°, scan loss below 2 dB/1.2 dB, and grating lobes below −10 dB. This design provides a cost-effective and simple structural solution for limited field-of-view applications requiring high performance and low grating lobes, with potential scalability for future mmWave vehicle systems.