Wilkinson Combiner and Antenna for High Power Microwave Applications : Development of a semiconductor-based HPM system in S-band

Sammanfattning

High power microwaves (HPM) typically have frequencies between 0.5 to 10 GHz. Using vacuum electronics such as the relativistic magnetron and backward wave oscillator, output powers in the range between hundreds of megawatts up to a few gigawatts can be achieved. These are used generate large electric far-field magnitudes, making them able to disrupt or destroy electronic equipment. Achieving such large power in a semiconductor-based system was previously not possible. However, recent advances in the semiconductor domain have enabled high power transistor amplifiers based on Gallium Nitride (GaN). This thesis aims to investigate the viability of such a semiconductor-based HPM system by the development and analysis of a power combiner and patch antenna module operating in the S-band. The module is intended to be used in a larger array structure, improving the antenna gain and total output power. A 4-1 Wilkinson power combiner and modified rectangular patch antenna module implemented on Aluminum Nitride (AlN) substrates is proposed. Simulations suggest that a combined average power of 25 kW is achievable without dielectric discharge or overheating. The patch antenna element is able to handle an average power of 15 kW. A 16-by-16 planar array consisting of such modules was able to achieve a realized antenna gain of 28.7 dBi and handle a total peak power of 3.84 MW, resulting in an electric far-field magnitude of 827 V/m at a 500 m distance. The proposed module consisting of a power combiner and patch antenna matched at 3 GHz can be suitable for a semiconductor-based HPM system, as it can handle powers close to 20 kW without the risk of breakdown or overheating.