Design and Construction of a Corrugated Feed Horn for Reflector Dishes

Student: Fook-Shin Mah

Supervisor: Nick Shuley

Category: Engineering Thesis Project - Communications

This thesis deals with the design and construction of an inexpensive conical corrugated horn that will produce symmetric radiation patterns, a good impedance match and low crosspolarisation. The principles of propagating modes have to be reviewed and this will facilitate the understanding of a hybrid mode that consists of transverse electric (TE) and transverse magnetic (TM) modes. This hybrid mode will produce an almost linear aperture field, and this field at the aperture will produce symmetrical E and H plane radiation patterns with low crosspolarisation. These radiation characteristics will determine the conical corrugated horn’s performance as a feed for reflector dishes.

One of the objectives of this thesis is to produce a low cost, small and compact antenna without compromising the copolar patterns. With limited resources provided, a unique design methodology was used. The conical corrugated horn was manufactured with aluminium plates. These plates have varying diameters in the centre and when bolted together, slots and ridges also known as the corrugations were formed. These plates have equal widths and changes can be easily made to the design by either removing or adding plates to it.

A PCAAD software was used to simulate the final design as well as to look at the differences in radiation characteristics between pure mode and hybrid mode horns. The conical corrugated horn was tested in the anechoic chamber for measurements of E and H plane patterns, crosspolarisation and return loss.

The final design has shown successful results with symmetrical E and H plane radiation patterns, good impedance match with a VSWR of 1.22, low crosspolar levels and a compact design.

Thesis Document (PDF)