Planar 9-element quasi-Yagi antenna array for X-band application

In this paper, a new planar antenna array based on 9 identical Quasi-Yagi elements is presented. In contrast to conventional designs, the feeding network is composed of 3-way power dividers, which are carefully designed in order to provide synchronised output signals over a wide frequency range. The use of spline-shaped microstrip lines suppresses coupling effects by parallel lines. Thus, signal distortions within the feeding network are minimised. Compared to conventional designs with 8 elements, the additional antenna element will enhance the gain of the array, which is between 10.5 and 13 dB in the XBand. The input return loss of the antenna array is below -15 dB over most parts of the relevant spectrum, with a total bandwidth of 45%. The planar antenna array is well-suited as a radiating element in linear phased arrays for multifunction radars including SAR and MTI.