Elliptically Profiled TEM horn
Image of the Elliptically Profiled TEM horn.

Horn antennas are used in many different applications - ranging from electromagnetic sensing to reflector feeds and biomedicine. Where a directional antenna that operates over a very wide band is required, TEM horns offer a good solution. These horns are designed by considering the transition from a bound TEM wave system to free space to achieve the best impedance match over a wide bandwidth.

The new TEM horn added to Antenna Magus (shown in the image below) is based on the basic TEM horn, but makes use of a modified Hecken taper in order to obtain an ultra-wideband impedance match. The separation between the metallic plates of the TEM horn is chosen based on an elliptic profile. Starting from a Hecken taper, an iterative optimisation is used to find the optimal width profile, achieving an excellent VSWR (below 2:1) across a bandwidth of 20:1 for a typical design.

Total gain 3D patterns at (a) 2 x fmin, (b) 8 x fmin, (c) 16 x fmin and (d) 20 x fmin
Typical VSWR behavior versus frequency