1-D Combline Leaky-Wave Antenna With the Open-Stopband Suppressed: Design Considerations and Comparisons With Measurements

The design of a 1-D planar periodic combline leaky-wave antenna that avoids the open-stopband effects as the beam is scanned through broadside is discussed and verified experimentally. This antenna radiates from nearly resonant stubs, which ensures a small leakage constant and hence a high directivity, and shows a single beam scanning through its n = -1 space harmonic in the X-band frequency range. The open-stopband suppression is obtained by applying a recently proposed matching technique within the unit cell that is experimentally validated here for the first time. Measurements are made of the phase and leakage constants, the S-parameters, and the realized gain patterns. Comparisons are made with numerical values obtained from specialized and commercial software and very good agreement is found in all cases.