A triple frequency feed for the QUASAT antenna

Connecting Early VLBI to SKA capabilities

“…Based on technical and mission considerations it was decided to combine systems and explore the use of a triple coaxial feed previously done in Westerbork in a dual feed 6/50cm arrangement in the seventies. Results were excellent [18] and a picture of the design is shown in Figure 9. Around the same time, it was decided to replace the multitude of receivers in the Westerbork array to reduce the operational load and maintenance, to increase observing bandwidths and to increase observing capabilities by accommodating a S/X receiving capability required for e.g.…”

Frequency multiplexing excitation network for ultra‐wideband coaxial waveguide feeds

“…Concentric coaxial waveguides have found successful application in feeds for reflector antennas that serve two or more operating bands, widely spaced in frequency, with separate TEM outputs for each band [1, 2]. Wideband operation has also been reported for nested concentric coaxial waveguides [3], also with separate TEM output ports for each frequency band.…”

“…2) show specific field patterns for TE 11 , TE 21 , and TE 31 modes. Anti-phase driving of the TEM port, commonly used in coaxial waveguide feeds [1,2], suppresses the TE 21 mode, which has an in-phase field pattern around the inner conductor as shown in Fig. 2c.…”

“…4 for a perfectly matched aperture. The frequency multiplexing and mode suppression are evident in the sub-band responses, and the overall input return loss is approximately 10 dB over the complete [1][2][3][4][5][6][7][8] Experimental verification: A feed incorporating the excitation network was built and tested. An important design step was to determine the waveguide scaling ratios.…”