Travelling wave antenna with non dissipative termination - has waveguide with matched open end which reinforces main lobe

摘要

An end-fire travelling wave antenna consists of a dielectric filled waveguide with non-resonant slots (23) cut across the wide side. A non-dissipative radiating termination is formed by continuing the waveguide a quarter wavelength beyond the last slot and leaving the end of the guide open. Three slots, longer than the antenna slots, are cut in this section to alter its impedance. This forms a quarter wave transformer to match the open end impedance to the antenna. Radiation from the open end adds in pahse and polarisation with the main antenna lobe. Measurement of an X-band antenna of this type showed a gain of 15.5dB compared with 15.2dB for the same antenna with a more expensive resistive termination.