Effectiveness of tape treatment in improving the performance of a panelled CATR at millimetre waves

The panelled approach is the technique usually adopted for the construction of the reflector(s) of a compact antenna test range (CATR) in order to fulfil the requirements of high surface accuracy needed for millimetre wave operation. However diffraction due to the edges of the interpanel gaps can affect the radiation pattern measurement accuracy by the formation of spurious lobes. In an attempt to rectify the situation a thin metallic tape can be used in order to cover the gap. This approach has been studied experimentally. The potential of improvement has been demonstrated, but this approach does not lead automatically to the complete elimination of the problems caused due to the discontinuity of the reflector surface at the interpanel junctions. Some results of a theoretical study concerning the tape induced scattering are presented in order to provide a realistic view about the effectiveness of tape treatment mainly at the 180 GHz bands