Substrate integrated waveguide slot array antenna with enhanced scanning range for automotive application

A modified substrate integrated waveguide (SIW) slot array antenna has been proposed for the low cost 24 GHz Doppler radar system. All radiating slots are connected in series using a short circuit ended SIW; therefore, its radiation beam can be steered with frequency. The modified antenna with meandering structure is proposed to enhance the scanning range. The physical slot spacing is kept at about half free space wavelength, while the electrical spacing is about 540° at the center frequency of 24 GHz. A broadside radiation is achieved at 24 GHz frequency and a ±30° continuous scanning range is experimentally confirmed with the frequency band from 23 GHz to 25 GHz.