NVIS Test Update #1

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Larry Gispert

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Mar 1, 2020, 10:07:06 AM3/1/20
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Reminder:  NVIS Test scheduled for Saturday March 7th at 0900.  The following frequencies may be used:

 

75 meters = 3.913 Mhz LSB

60 meters = 5.370 Mhz USB (CH-3)

40 meters = 7.282 Mhz LSB

 

Note: 60 meters is USB in order to keep emissions within the F.C.C. mandated channel limits

 

We will obtain the Maximum Useable Frequency (often called the FoF2) info to determine which freq to use. NVIS theory suggest using the amateur band that is closest but below the projected FoF2 frequency.

 

Antenna height above ground – NVIS Theory suggest that your horizontal antenna should be between .10 and .15 wavelengths high. We selected 10 to 15 feet because we normally would be setting up portable using PVC pipe as antenna supports and that height is a good compromise for 80, 60 and 40 meters which would be the normal amateur bands used for NVIS communications. The U.S. Military utilizes an AS-2259/GR antenna with a center support pole of 15 feet for NVIS communications. You can do a web search and find the plans for building such an antenna.  DX-Engineering sells a kit (minus PVC pipe) for building such an antenna.

 

If you are interested in learning more about the Theory behind NVIS Communications you can do a web search and find a free PDF download of the manual: Near Vertical Incidence Skywave – Theory, Techniques and Validation by: Fielder and Farmer. This manual is considered by many to be the “Bible” of NVIS.

 

I will be putting out a “Communications Procedure Plan” for the test as we get closer to Saturday.

 

Enjoy the Hobby

 

de KR4X 73

 

 

 

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