Design and optimisation of a high-frequency EMC wideband horn antenna

Abstract

A new approach for the design of high-frequency electromagnetic compatibility (EMC) broadband double-ridged horn (DRH) antennas is presented. In this approach, first a conventional DRH antenna at 1-18 GHz frequency band is considered. Using a thorough sensitivity analysis of different structural parameters of the 1-18 GHz DRH antenna, several modifications are applied to this antenna to overcome its deficiencies especially in its radiation pattern at higher frequencies. The final achieved design is then scaled up in the frequency to arrive at a design suitable for higher frequency ranges. A wideband DRH antenna for 18-40 GHz frequency band is then designed using this approach. The lower frequency ratio of 1:2.2 in the new antenna as opposed to the 1:18 ratio in the conventional antenna permits us to choose the best frequency window for the scaling up process. Besides, an optimisation technique is employed to further improve the antenna performance to meet the design goals over the entire new frequency band, that is, to have a single main lobe directed along the horn axis without any deterioration, and to have acceptable broadband gain with the minimum of 10 dB, and voltage standing wave ratio (VSWR) of less than 1.5. The final design which is more compact compared with the other commercial antennas has been used to make a prototype antenna. Measurements show that the built prototype meets the design goals very well