Composite right/left-handed waveguide beam-steering leaky-wave antennas using a cut-off waveguide and short-ended stubs

Simple and scalable composite right/left-handed (CRLH) waveguide slot antennas using a cut-off waveguide and periodic short-ended stubs are proposed for low-loss and high-power applications. It is shown that the balanced CRLH condition can be realized and the CRLH waveguide can be used as a leaky-wave antenna with backward to forward radiations including broadside radiation by introducing small radiation slots. In addition, it is shown that the CRLH waveguide can be excited directly by a standard rectangular waveguide with an appropriate Bloch impedance design. A balanced CRLH waveguide antenna is designed at X-band and a wide range beam steering operation from -61 deg to 78 deg is confirmed.