Analysis of Wideband Dual-Polarised Vivaldi Sub-Array Topologies at Ku and Ka Band

A <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$2 \times 2$</tex> sub-array of Vivaldi antennas for dualpolarised and low-cost antenna measurements is proposed with three alternative methods of antenna transformation. In each case the antenna design is considered from a cost and complexity perspective and simulated to characterize the performance of each design. The Vivaldi antenna element can achieve wideband coverage from <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$10-30 \text{GHz}$</tex> and dual polarization is enabled by each sub-array. While each design performs almost identically at lower frequencies, at higher frequencies it is found that there are some impacts to the radiation pattern and polarization discrimination. As a result of this work, it is found that the topology that uses a translated element provides the best performance at the lowest cost. As the translated design does not require any rotation between elements of the same polarization, no phase difference is required for constructive combination of the two channels. Hence, only a simple combiner is required to enable both elements to be added to a single RF channel. This work provides a clear analysis of three common forms of such subarrays and presents recommendations on both cost and performance trade-offs.