Dual-band Ku-band Scanning Leaky-Wave Antenna for Satellite Communications

Fabry-Perot (FP) cavity type Leaky Wave antennas (LWA) have been extensively used to tailor the radiation pattern of low directive sources [1-4]. One can realized these antennas by placing Partially Reflecting Surface (PRS) over a ground plane (GP) forming a half-wavelength Fabry-Perot cavity. The cavity, excited by a source located at the center of the structure, is capable of concentrating the radiated power into highly directive pencil-beams at the frequency of operation and conical beams above it. In the last few years, these antennas have received significant attention due to their interesting properties, low complexity feeding network, high efficiency and compatibility with established manufacturing technologies. There is a significant effort to improve their efficiency, thickness and more recently their bandwidth. Indeed, the higher directivity typically results in a narrower bandwidth which is a disadvantage in modern communication systems. Different approaches have been adopted to overcome the bandwidth limitation. Some authors proposed to replace the feeding network by using a sparse array feed rather than a single element unit, increasing the radiating aperture size and thus widening the bandwidth of the antenna for a fixed gain value [1]. However, this design adds complexity in the antenna implementation due to the multiple feeds. Different approaches also involve tapering the PRS employed or using artificial magnetic conductors [2-3]. Mateo-Segura et al. [4] proposed a broadband FP antenna design with compact lateral dimensions using double-layer metallo-dielectric PRS with different array element size (i.e. arrays with dissimilar reflectivity). The double-layer array configuration provided a reflection phase response that increased almost linearly with frequency within a frequency range. As a result, the resonance condition of the cavity was satisfied over a wider range of frequencies thus increasing the antenna bandwidth. However these antennas are bulky. In this work we present a novel reconfiguration mechanism were by physically modifying the cavity thickness of the FP type LWA the operating frequency of the antenna can be tuned. Figure 1 shows the near fields for a varying antenna cavity. As expected from a ray optics model, lower cavity profiles yield operation at higher frequencies.