16 X 12 Element NBS 2.2 wavelength Yagi array

     (Replaced in Oct. 2000 with THE DISH)

 

These are the results of my strip chart recording of sun noise which shows interesting lobing and nulls on the radiation pattern of the 16 by 12 element array.  This antenna is no longer in service. I believe some of the irregularities were due to bad solder connections in a couple of the 4-way power dividers which I found when I took the array down.

Notes:

  1. The noise baseline at a relative value of 10 was set at cold sky noise.
  2. The array is pointed at 180 degrees azimuth and 52 degrees elevation and the measurement was run for about 3 hours.
  3. The strip chart is linear mode only
  4. Based strictly on graphical measurement, the beam width of the array taken at the -3 dB points (relative 40) appears to be about 16 degrees (ignoring the chop on the + side)
  5. This recording was taken with significant breeze which caused the array to rock +/- 3 or 4 degrees.
  6. The peak signal reading = relative 80 compared with cold sky of relative 10 equals about 9.0 dB of sun noise? I don't have a step attenuator to do an absolute measurement.

 

Observations:

  1. The sidelobe at +18 degrees is fairly clean whereas the sidelobe at about -18 consists of 3 distinct lobes.
  2. The pattern between about +3 and +12 degrees consists of various lobes and nulls and is not at all clean.
  3. The peak of the beam at 0 degrees is very flat and almost appears to be clipped, perhaps a problem with my test setup, although I find no obvious problems.

 

Comments are welcome at kl6m@arrl.net

 

Thanks.

 

KL6M