Design of an Electrically Long Leaky Wave Antenna Based on a Substrate Integrated Waveguide for a 24 GHz Doppler Radar

The paper describes the design technology for a leaky-wave antenna based on a substrate integrated waveguide that radiates waves at a given angle. Doppler speed measuring devices with improved accuracy characteristics use these antenna types. The presented results for a short antenna are used to adjust the dimensions of the substrate integrated waveguide and radiating slots. The proposed design utilizes the RO3003 substrate. The radiation pattern and the electromagnetic field strength in the near field are presented for electrically long leaky-wave antennas. The amplitude distribution over the antenna surface decreases and distorts the radiation pattern for a structure with uniform periodical slots. The slots are combined into groups with different lengths to equalize the amplitude of the near-field distribution and overcome this drawback. Thus, it is possible to obtain a distribution close to uniform. This paper presents the simulation results of the near-field distribution, directivity, and S-parameters of the optimized antenna structure.