Antipodal strip broadband leaky-wave antenna

The radiation characteristics of a broadband leaky-wave antenna based on antipodal strip conductors are investigated in this paper. This structure has only two single-strip conductors on opposite sides of the dielectric substrate. By using the full-wave integral equation method in the spectral domain and the method of moments, the EH/sub (1)/, leaky mode of this single-conductor strip structure is investigated and found to possess a broadband radiation regime. To excite this first higher order leaky mode, a feeding network utilizing broadband planar baluns is developed from the balanced microstrip lines and the balanced microstrip line phase inverters. Both the numerical simulation and the measurement data are presented. The measured return loss exhibit a bandwidth of 3.64:1 (from 11 GHz to 40 GHz) for a VSWR/spl les/2.