Notch Antennas

Reflector Systems

Passive Components

Multiband Systems

Wideband Systems

Installed Performance

High-power Components

High-power Antennas and Components

MAAS has successfully designed and built many antenna and passive components for high power, a few of which are described below.

• a C-band feed chain for the 25m reflector at Defford was built for use with many kilowatts of CW power (Figure 1). The feed chain was for use in Circular Polarisation and a polariser was required. Because of the power requirements, this was implemented as a squashed plate polariser (Figure 2)

• a D-band horn for high power which had a very restricted permitted volume (Figure 3). The horn was shaped internally to provide good Return Loss and gain performance. Peak gain is 12 dBi.

• a very short D-band horn for high power, for a very restricted volume (Figure 12). The horn was provided with radiused steps which resulted in a good Return Loss and a peak gain of 17dBi. The final horn length was 45% of that of a standard horn of the same gain.

• a scanning reflector covering 8 to 12 GHz (Figure 4). Because of the exceptionally high CW power, a rotating joint was not possible. The exponential horn (Figure 5) was fixed and the reflector alone was rotated.

• a side entry coupler for use over 8 to 18 GHz in a Free Electron Laser (Figure 6 and Figure 7). The Return Loss was better than -24 dB across the 8 to 18 GHz band required (Figure 8).

• a CVD diamond window for use over 8 to 18 GHz with a Free Electron Laser (Figure 9). This window was curved with a radius of 35 mm. The thickness was 130 +/- 10 microns and Figure 10 shows the measured and predicted insertion loss. Figure 11 shows the measured Return Loss compared with predicted Return Loss for various thickness of the diamond window.

Figure 1 Feed Chain for C-band. Comprising exponential horn, squashed plate polariser, transition from circular to rectangular waveguide, transition to coaxial line

Figure 2 Sectioned view of squashed plate polariser

Figure 3 D-band Shaped Horn

Figure 4 Scanning Reflector for high power

Figure 5 Horn for scanning high power reflector. The transitions are for testing

Figure 6 Side Entry Coupler

Figure 7 Solidworks model of Side Entry Coupler showing interior

Figure 8 Return Loss of 2 versions of the Side Entry Coupler

Figure 9. Photograph of CVD diamond window inserted in its waveguide housing

Figure 10 Measured and Predicted Insertion loss for CVD diamond window

Figure 11 Measured and Predicted Insertion Loss for CVD diamond window

Figure 12. Photograph of short D-band horn looking into the aperture