Dr Felix Vega has introduced an innovative version of the HIRA (Half Impulse Radiating Antenna), called the Tapered-Impedance HIRA (TI-HIRA). TI-HIRA simplifies the complete radiation system chain. HIRA is a well-known antenna used to radiate very high-voltage electromagnetic pulses that are useful in various applications. These uses include in radar systems, electromagnetic susceptibility tests of electronic equipment and infrastructure, communications systems, electromagnetic warfare, and ground-penetrating radar.
In his paper entitled “The Tapered-Impedance Half Impulse Radiating Antenna”, Dr Vega describes how the innovation relies on the simplification of the complete radiation system chain by avoiding the necessity of using external impedance adaptors, which are bulky, expensive, and difficult to manufacture. This new TI-HIRA allows the direct connection of commercial pulsed generators directly to the antenna. In this way, pulses up to 75 kV, from generators already available in the market, can be straightforward radiated into space.
This approach uses shaped feeders, mathematically conformed to give the optimal voltage level at the reflector dish of the antenna, as depicted in the figure below. The name, “Tapered-Impedance”, (impedance is a key parameter that characterises any radiator) comes from the fact that the proposed TI-HIRA implements an impedance progression within the antenna itself.
The additional effort required to manufacture the new profile is offset by the reduced number of electrical and mechanical parts required to operate the new radiating system. The design is discussed and validated in the paper, both analytically and by full-wave simulations demonstrating that the performance of the original HIRA remains.
The figures below present the proposed TI-HIRA, as well as a close view to the conformal feeder of the TI-HIRA, compared to a conventional one.
(a) General view of the proposed TI-HIRA with exponential progressive feeders, directly connected to a 50 Ω generator. (b) Conformal feeder profile of the TI-HIRA (continuous line) and its counterpart, the feed of the conventional HIRA (dashed line).