The Ka-band (20/30GHz) satellite offers excellent potential for transportable and mobile communications due to the wide bandwidth available and the high gain achievable with small antennas. There are some difficult technical challenges in realizing this potential. While relatively small antennas, such as 500-1000mm parabolic reflectors, give high gain of the order of 40dB the beam widths are quite narrow, of the order of 1deg, and the antenna has to operate at both the 20GHz receive band and the 30GHz transmit band.