A multiple burst, variable frequency, high power driver for antenna characterization

Abstract

Compact high power antennas are actively being developed at the University of Missouri. While the antennas are preliminarily characterized through network analysis techniques at low power, high power evaluation is also necessary to ensure operation is consistent when driven at high voltage. Thus a high power driver was required to evaluate antennas in two ways that cannot be accomplished at low power. First, high power evaluation enables diagnosis of potential points of insulation failure due to solid dielectric breakdown, flash over, or corona formation on the antenna structure. Second, the peak radiated fields can be directly measured when the antenna is driven at high power. The high power antenna driver was designed for flexibility in the peak output voltage, the driving frequency, and operation as a single or multiple burst source. An inductive energy storage system with an exploding wire fuse is utilized to achieve the high peak power levels required for testing. The current profile of the capacitive discharge feeding the inductive energy storage system can be modified from that of a simple capacitive discharge to that typical of an explosive generator. Upon vaporization of the exploding wire fuse, the inductive energy storage system charges a high voltage transmission line, which is discharged at peak voltage to form an oscillator in the VHF to UHF bands. The antenna under test is driven in parallel with the high voltage transmission line. The peak charging voltage and output power can be modified through adjustments to the inductive energy store, the exploding wire fuse, and the energy delivered to those components. The frequencies at which the antenna is driven can be tuned by modifying the parameters of the high voltage transmission line and exploding wire fuse. Lastly, the driver can operate in single or multiple bursts by modifying the impedance of the exploding wire fuse in time. A detailed description of the high power antenna driver is provided, and descriptions of the critical component designs are given. Simulated results of the driver's performance are presented to demonstrate the peak power and multiple burst capabilities designed into the system.