Simple surface-wave launching by parallel-plate and microstrip feeding for leaky-wave antennas and other planar guided-wave applications

A simple parallel-plate waveguide (PPW) with a microstrip feed is proposed for efficient TM0 surface-wave (SW) mode excitation. In particular, by means of a truncated PPW and a printed sub-wavelength matching section, phase constants can be tailored and matched at discontinuities. This surface-wave launcher (SWL) offers an attractive microstrip feeding approach to LWAs and is an alternative to more conventional feeding networks that are typically employed for dielectric image guides (DIGs) and other planar structures because of its good performance, low cost and simple implementation. The proposed SWL has been designed to operate at K and Ka bands in a substrate with a relative permittivity of 10.2. In order to validate its performance in a LWA or for other planar applications, several scenarios have been designed and simulated: an end-to-end test circuit, a 1-D LWA and a DIG feeder. High efficiency and wideband operation have been obtained for all these structures. The proposed SWL with a microstrip feed can also be useful for other planar wave guiding structures at microwave and millimeter-wave frequencies.