Measurements of a compact Ku- and Ka-band 4×4 array for remote sensing

This paper presents the measurement results of a dual-band (Ku and Ka), dual polarization 4×4 array that fits within the surface of a Cubesat satellite. Each sub-array has two polarizations, namely vertical and horizontal (or 0° and 90°). The design uses a multi-layer structure such that the Ka-band (35 GHz) array is embedded within the empty space provided by a 2×2 Ku-band (14 GHz) sub-array. The feeding networks for both arrays are etched on the same substrate layer without overlapping of the transmission lines, while adequate space is provided to incorporate amplifier chips directly onto the network. The proposed array has similar radiation patterns at both frequencies with high gain and large front-to-back ratio. Adequate space for integrated phase-shifters is provided for beam steering and a proof-of-concept digital calibration scheme. The array is fabricated on a stack of PCB milled substrates. Measurements of scattering parameters are performed and matched the simulations. This array is compact and offers additional functionality compared to traditional single frequency and/or single polarization designs, and is suitable for airborne and small-satellite remote sensing applications.