Differentially Fed High-Power Microwave Antennas Using Capacitively Coupled Hyperband Inverters

Abstract

For high-power electromagnetic (HPEM) applications at high-repetition rate, conventional microwave inverters based on pulse transformers are not practical. At high-repetition rates, the magnetic materials used in the inductive coupling saturate. In this paper, we present an alternate concept for an inverter based on the technology used for ultrawideband baluns which provides isolation through capacitive coupling. Design of the device is discussed through numerical modeling, and two implementations are built and demonstrated: a circuit element version and a transmission line version. The devices are demonstrated at charge voltages of 6 kV and repetition rates up to 100 Hz, with excellent performance between 20 MHz and 2.5 GHz. The circuit element device has a rise time of 445 ps with an insertion loss of less than 3 dB, while the transmission line device has a rise time of 240 ps with an insertion loss of less than 2 dB for most frequencies. The inverter is demonstrated as part of the feed network for a hyperband HPEM antenna with a differential input.