KL7UW

  1296-1420 MHz Septum Feed:

   The septum feed is a square waveguide that utilizes a stepped metal septum plate which results
   in both RH and LH circular polarization appearing at coax probes mounted on opposite sides
   of the feed. This permits using the dish for EME, transmitting RHCP and receiving LHCP;
   RA and SETI reception is also LHCP.  A coax relay inserted between the feed and the LNA
   increases isolation from the transmitter input.  It also provides a 50-ohm ambient termination
   for making noise comparisons with cold sky.

   For more information on this feed design look at OK1DFC's website or W1GHZ's analysis.
   Read also the 2007 update to W1GHZ's analysis: 
   Also read my Microwave Update paper on the septum feed
   Here is the Power Point presentation (1.32 Mb) made to SARA at Greenbank NRAO in June, 2006.

   Here are a couple photos of my septum feedhorn:
 

















  For info on the original helix feedhorn at RA Feed page.
  Here is more info on the 1296 EME station.



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