A cone shaped taper anechoic chamber for antenna measurements in the 200 MHz to 18GHz frequency range

Traditionally Taper chambers are constructed using a square based pyramidal shaped taper. The taper is then shaped into an octagon and finally transformed into a cylindrical launch section. This approach is related to the manufacturability of different absorber cuts. This presentation introduces a chamber where the conical shape of the launch is continued through the entire length of the taper chamber. The results of the free space VSWR test over a 1.5m diameter quiet zone are presented at different frequencies in the range from 200MHz to 18 GHz with quiet zone reflectivity levels that exceed -30dB. The conical taper appears to have a better illumination wave front and better QZ levels even at frequencies above 2GHz than the standard traditional approach. The conical taper also appears to be more forgiving to the use of lower gain antennas as the feeds for the taper range when compared with traditional designs.