Folded Horn Antennas

Antennas for radiating high-power mesoband electromagnetic signals are critical to the mission of upsetting electronics at a distance. High Power Microwave (HPM) weapons require highly efficient antennas that can fit into a small volume. An example of such an antenna is the half Impulse Radiating Antenna (IRA) driven by a switched oscillator source in the MATRIX system. However, the half IRA has a relatively low aperture efficiency of 25-35%, because it has been optimized for Ultra-Wideband (UWB) operation. To address this problem, we propose the folded horn. When operating at 500 MHz, this will have an aperture size of 0.3 X 1.2 meters (0.5 X 2 lambda), with a nearly focused aperture field, due to a parabolic bend. This design provides nearly uniform aperture illumination, with no losses due to spillover. Furthermore, two folded horns may be positioned back-to-back, to create a 1.5 X 3-meter aperture, both of which are driven by a dual source using a single trigger. When compared to a comparably sized half IRA operating at the same voltage, the folded horn will deliver 2.8 times the radiated field and 8 times the power on target, according to calculations provided here.