Miniaturized SIW-CBS Planar TX/RX Antenna Arrays For Microwave CW/FMCW Doppler Radars

Miniaturized Substrate Integrated Waveguide Cavity-Backed Slot (SIW-CBS) planar transmit and receive (TX/RX) antenna arrays are presented. A composite right/left handed (CRLH) structure is used as an interdigital slot on the topside of the SIW cavity to achieve the miniaturization. A two-layer substrate structure is used to isolate the antenna from the potential radar electronics. The resonance frequency and bandwidth are set to be 5.8 GHz and 50 MHz. The array miniaturization ratio achieved by the antenna element employing the CRLH structure is ~60% and ~20% compared to a rectangular slot SIW-CBS antenna array and a patch antenna array, respectively. Each array shows a pure radiation pattern with the gain of ~15 dB and 12 dB of front-to-back ratio.