Advanced Feeds for mm-Wave Antenna Systems

Abstract

Millimetre-wave antenna systems have traditionally required high performance feeds in order to fulfil its stringent requirements. Therefore, this goal has been achieved by corrugated horns. However, in the last years new applications mainly in the communication area have driven the use of other types of antenna feed with slightly reduced performance but simpler manufacturing and reduced cost. The simplicity of manufacturing is especially critical as frequency increases and in fact corrugated horns are extremely difficult and expensive to manufacture at submm-wave frequencies.This chapter will cover the different alternatives currently used for mm-wave and submmwave antenna feeds: corrugated horns, smooth walled horns where multi-flare angle horns and splined horns will be introduced as alternatives to corrugated horns at mm-wave and submm-wave frequencies. Finally, the chapter will finish with the perspectives and actual research results regarding metamaterial based feeds towards future applications. Advanced corrugated horn antennasThis section describes the actual corrugated feed horn technologies employed at mm-wave frequencies. It begins explaining the principles of the electrical behaviour of the electrical fields inside a corrugated waveguide. The hybrid mode basis as a tool to help in the analysis of corrugated horns and the relation between waveguide modes and free space gaussian modes are explained to understand the behaviour of the different types of corrugated horn antennas.In fact, corrugated feed horns are difficult to manufacture as frequency increases and usually are not usually used above W band. The reason is that their manufacture results quite difficult being necessary to use for the manufacture expensive electroforming techniques or even stacked rings if the weight is not an important parameter. 4.2.

Wideband Corrugated Feedhorns, for Radar, Communications, Radiometry and Quasi-Optics

“…Constant gain horns have previously been outlined by Olver [2], who pointed out that wide angle linear tapered horns had approximately constant gain for certain taper lengths over limited bandwidths, albeit with rather poor broad beam patterns. A highly compact design with a constant gain operating over 20% bandwidths has also been described for a body scanner application, with low sidelobes and cross-polar < -30 dB and return loss < -22 dB [4]. It can be shown that such a constant gain horn requires precise dispersive properties between modes and in Section IV we demonstrate a design that can operate over full waveguide bands with reasonable beam quality.…”

“…Today, beam patterns from corrugated feedhorns can be modelled with extraordinary accuracy using mode matching software and there is now a significant literature on their design and optimization including a number of books and review articles [1], [2], [3], [4]. Often, initial designs are based on general geometric arguments and improved by computational optimization programs [5].…”

A Wideband Millimeter-Wave Corrugated Horn at 30–50 GHz Taking Advantage of All-Metal 3-D Printing Fabrication

“…Commonly, mm-wave corrugated horns are fabricated by direct machining [9] or electroforming [10], but these fabrication techniques require medium to high cost and long delivery time. Recently developments propose the use of platelet technique to fabricate wideband mm-wave corrugated horns which is able to reduce the cost [11], [12], but the mechanical robustness during thermal cycling is one of the main concerns of this technique.…”