Additional lens for TEM horn antenna and transient high-power application: Design and Characterization in time domain

This paper presents the design of a dielectric lens dedicated to transient High Power Microwaves (HPM) short pulses radiation. The proposed lens has been developed as an optional component that could be used to increase the directivity, and therefore the range, of a mobile HPM source. The associated emitter consists in a TEM horn, powered by a Marx generator and a dedicated pulse forming line (400 kV - 50 Ohms output voltage, total duration of 1.5 ns) [1]. The emission of very high amplitude nanosecond signals covers an ultra-wideband of frequencies, so the design of the lens was carried out in time domain. Here, the goal was to convert the pseudo spherical wave into a plane wave at the aperture of the aerial, for the considered impulse. Once manufactured, the near fields and the far fields have been measured with and without the lens. The maximum gain increases by at least 6 dB beyond 1.3 GHz and can reach 12 dB for higher frequencies. In time domain, the peak amplitude has been multiplied by a factor 2.65 allowing to reach a figure of merit of 2 MV/m.