Suppression of second order beam for traveling wave slot arrays

Second order beams in the far-field patterns of a typical two-dimensional edge slot array antenna is in general unavoidable and severely deteriorates the antenna far-field pattern performance. For instance, the peak level of cross component lobes could far exceed the originally designed side lobes level of the principal polarized component of the far-field antenna patterns and as a result, increases the susceptibility of the corresponding search radar when detecting spurious target echoes. The purpose of this work is that an empirical guide line can be summarized for the suppression of the second order beam magnitude by tuning the depth of the ground plane from the antenna aperture surface of a two-dimensional edge slot array. Due to its frequency-independent feature, the effectiveness of applying this suppression technique for antennas operating at different bands other than the tested 8/spl times/21 element S-band edge slot array is expected.