A Rectangular Waveguide Antenna with Filtering and Beam-steering Capabilities

In this contribution, we discuss a convenient technique for designing rectangular waveguide filtering antennas with reconfigurable radiation properties. The basic structure we consider is an open-ended WR-137 rectangular waveguide working in the frequency range 5.85-8.20 GHz, with a stable realized gain around 7 dB. We will show that by placing two electrically small resonators at the end of the waveguide, the bandwidth of the overall structure can be reduced with important advantages in terms of noise/interference rejection. Moreover, by loading each resonator with a varactor diode, the phase shift introduced by the two elements can be controlled and, thus, exploited for steering the radiation pattern of the antenna.

I. Introduction

Open-ended waveguides are standard radiators exhibiting moderate directivity and a stable radiation pattern over a wide impedance bandwidth. They are typically used for feeding reflector antennas but, for satellite communications, some filtering strategies should be employed to narrower their operating bandwidth and, thus, reducing the out-of-band noise. A possible solution is to integrate the filtering elements directly inside the radiating structure, such that the overall complexity, cost and dimensions of the system are minimized [1]–[6].