An X-Band Substrate Integrated Waveguide Fed Patch Array Antenna: Overcoming low efficiency, narrow impedance bandwidth, and cross-polarization radiation challenges

Abstract

In this article, the efficient development of a new class of multilayer microstrip patch antenna (MPA) fed by a substrate integrated waveguide (SIW) for X-band applications is presented. It consists of performing the feed network in the SIW and the radiating structure in the microstrip technology. The proposed structure demonstrates that the best alternative to a costly, heavy, and bulky rectangular waveguide feeder is an SIW, which provides miniaturization, performance enhancements, cost reductions, and ease of integration with MPAs. The proposed patch array is composed of three stacked layers from top to bottom, including two SIW layers as a feeding network and one layer as the antenna layer. To verify the concept of the proposed antenna, a prototype of a 2 × 2 SIW patch array with a 39 × 41 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> physical aperture was fabricated and measured with an impedance bandwidth of 9.18% for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\left|{{S}_{11}}\right|{&lt;}{-}{10}\hspace{0.33em}{\text{dB}}$</tex-math></inline-formula> and a radiation efficiency above 78% in the whole operating frequency bandwidth. The maximum measured gain of the proposed array at 10 GHz is 11.1 dB, which is equivalent to 57.7% of the aperture efficiency. The proposed array can be easily developed to be used in larger arrays, and it is a good candidate for generating a symmetrical unidirectional pattern with a low cross-polarization level.