Design and optimization of a shaped-beam ka-band substrate integrated waveguide antenna array

Millimeter-wave antenna array Beam Forming Networks in Substrate Integrated Waveguide (SIW) technology are an attractive alternative to the use of TEM transmission lines, such as microstrip or stripline. SIW allows reducing the transmission losses while maintaining low price and simple, yet accurate, fabrication of the Printed Circuit Board technology. However, SIW design has additional restrictions and limitations when compared to TEM transmission lines. This includes increased footprint, a need to use additional transitions to other transmission lines or some types of radiating element as well as a more complicated overall design. In this contribution the authors propose the design of a Ka-band antenna array, which extensively uses SIW technology. The design is based on the requirements of a real-life satellite application. These include limitations imposed on return loss bandwidth, gain, radiation pattern shape, and polarization. Moreover, also the feeding method is imposed and the antenna array footprint should be minimized. A prototype of the proposed design has been fabricated and measured. The results show a 8.9% return loss bandwidth, a 12% circular polarization bandwidth and a radiation efficiency over 60%. The obtained RF performance as well as other aspects, such as footprint, are compared with an alternative state-of-the-art design, which has been developed according to the same requirements but using different architecture and technologies.