Broadside Radiation in Leaky-Wave Antenna Using Multiperiodic Width-Modulated Microstrip Lines

An analytical-numerical method in a multitone modulated dielectric medium is presented for the transverse magnetic mode of which the wave equation is in the form of the Hill equation. In order to suppress the second stopband, dispersion characteristics are analytically considered in terms of “stability chart” and “dispersion diagram.” Having suppressed the second stopband in the multitone modulation of a dielectric medium, an effective value of the dielectric constant is realized by width-modulated microstrip lines in a grounded dielectric substrate. Then, a new planar leaky-wave antenna is designed and fabricated based on multitone periodicity for broadside radiation at 14 GHz. The fabricated antenna is able to scan through the broadside without any drop in the gain near the broadside. Simulation and measurement results are in a good agreement with theoretical results.