Two dimensional modelling of antenna pattern measurements in a panelled compact range at millimetrewaves

Antenna measurements at high millimeter-wave bands with a paneled compact range are influenced by the existence of gaps. The main effect here is the formation of spurious lobes. Its angular extent is determined by the rotation angles resulting in strong illumination of the gap, assuming the test antenna is transmitting. The effects of gaps directly in the measured pattern were studied, mainly at the frequencies around 180 GHz, where some experimental results were available. The strength of the lobe is affected by many factors: gap width, gap edge misalignment, relative antenna position, antenna size, polarization, and in 3-D the relative orientation between the gap and the path determined by the test antenna axis during rotation. However, the influence of the gap edge misalignment is quite significant. This will be true as long as the misalignment is larger than about lambda /50, especially when the gaps are electrically small. To this end the construction of a paneled CATR should favor the biggest possible size panels.<>