Uniform Periodic Leaky-Wave Antennas With Eliminated Open Stopbands

This letter studies an open stopband elimination method for a class of periodic leaky-wave antenna (PLWA) composed of two varied uniform transmission lines in alternatively cascading arrangement. By using a transmission line model, a dispersion diagram is extracted and an equal phase shift condition of β1L1= β2L2is proposed to eliminate the open stopband at broadside. The working principle is illustrated by numerical extraction and calculation. To verify the proposed method, an antenna prototype with two kinds of transmission lines-microstrip lines with and without covering strips-is accordingly designed and fabricated. Furthermore, simulated and measured results coincide well with the numerical prediction, showing that the proposed strip-covered uniform PLWA owns a certain radiation capability to continuously scan through the broadside direction.