Broadside radiation from radial arrays of substrate integrated leaky-wave antennas

In this work it is proposed a radial array formed by N = 8 substrate integrated waveguide (SIW) leaky-wave antennas (LWAs) which are fed in the centre by a vertically-polarized point source. It is shown how, by properly designing three parameters of the SIW LWA element (namely the radiating length L_A, the SIW width W, and the spacing between SIW vias P), the split-off condition for optimized broadside radiation can be satisfied, while keeping high radiation and illumination efficiency. In order to efficiently obtain the printed-circuit parameters of the LWA, a design technique based on a simple transverse equivalent network of the antenna cross section will be used. In addition, the designs will be validated with commercial full-wave software HFSS at the operating frequency of 15 GHz. Finally, a comparative between the directivity of a single LWA element (D_E) and the complete radial array (D_A) will be done for different antenna lengths, and the benefits of using this radial configuration will be addressed.