A bi-cylindrical lens for a DRGH antenna

Abstract

Broadband double-ridged guide horn (DRGH) antennas are extensively used in antenna measurement and electromagnetic compatibility and interference testing, especially the 1–18 GHz DRGH antenna, which is widely accepted as a standard for this band. Increasing the gain of the DRGH will result in higher field strengths for EMI testing and increased sensitivity in antenna testing facilities. In this paper, a complete wideband near-field E- and H-plane phase center analysis is performed with CST, at observation points over a region inside the flared section and also outside the aperture of the DRGH. A new plano-convex intersecting bi-cylindrical lens was designed using the two discrete phase centers corresponding to the statistical mode of samples from the population of phase centers obtained from the simulated phase distributions. This new lens is a practical implementation with both convex surfaces on the inside and a planar surface on the outside of the DRGH. This makes manufacturing and mounting the lens much easier without significantly increasing the size of the DRGH antenna. The bi-cylindrical lens significantly increases the boresight gain of the DRGH antenna, while simultaneously reducing the variation in 3 dB beamwidth over most of the operating band.