The Tapered Impedance Half-Impulse Radiating Antenna

In this article, we introduce the tapered impedance half-impulse radiating antenna (TI-HIRA). This innovative version of the HIRA allows the direct connection of COTS, 50 Ω generators to the antenna, without requiring external transformers and without using the large, blocking, plates that would be required in the traditional constant-impedance case. The idea relies on the use of feeders having a characteristic impedance that increases progressively, as a function of the radial distance between the focal point and the parabolic reflector. The additional effort required for manufacturing the new profile is offset by the reduced number of electrical and mechanical parts required for operating the radiating system. Various impedance profiles for the feeders are presented and compared. The design is discussed and validated, both analytically and by full-wave simulations demonstrating that the performances of the original HIRA remain.