Theory

A new leaky-wave antenna is presented here that possesses many desirable features and is suitable for application to both the millimeter-wave and microwave ranges. These desirable features, some of which are unusual, include a simple configuration, a wide flexibility in the range of available beamwidths, the ability to control the beamwidth and the direction of the beam essentially independently, and negligible cross polarization at all scan angles. The antenna structure consists of a parallel-plate stub guide of small height, less than a half wavelength, located off center on the top of rectangular waveguide. The beamwidth is easily controlled from very wide to very narrow by adjusting the stub width or location. Part I presents the principle of operation and the theory, employing a new transverse equivalent network that is accurate, but also simple, so that it permits rapid and inexpensive numerical calculations. Part II describes and derives the modifications required in the theory to account for flanges and/or finite stub length, and Part III is devoted to measurements at X-band and from 40 to 60 GHz on both the propagation properties and the radiation patterns; excellent agreement with the theory is demonstrated. Index Terms - Leaky-wave antennas.