Design of a Low-SLL SIW Slot Array Antenna With a Large Declination in $Ka$ -Band

A small-size large-declination longitudinal slot array antenna based on substrate integrated waveguide (SIW) technology was proposed. Compared with the conventional SIW slot array, the proposed antenna achieves a larger declination and a lower SLL. The antenna is mainly composed of three parts, a dielectric substrate, a coaxial port, and a matched load. The antenna contains 13 radiation slots, and the adjacent slot spacing is greater than half of the waveguide wavelength, so the main beam is biased towards the load. To achieve low sidelobe levels (SLL), the amplitude distribution of the 13 slots is based on Taylor synthesis of SLL = -25 dB. The antenna was processed and measured. From the measured results, the antenna achieved a beam declination of 26° and a SLL below -20 dB from 35.2 to 35.8 GHz. With the same number of slots, the length of the slot array of the SIW structure is only 44.8% of the length of the standard metal hollow waveguide. Based on the performance achieved, the SIW slot antenna is an excellent candidate for carrier conformal and large declination applications.