On Sun,4/30/2017 11:34 AM, [email protected] wrote:
Plus the antennas can be ad hoc - tossed into trees or even an old fence line.
There's a bit of fiction in the belief that antennas must be very low for NVIS. Fact is that higher is better, up to a quarter wave. The optimum height for a horizontal antenna for NVIS is a quarter wave length, and performance declines only slightly (1 dB) up to 3/8 wavelength. High angle radiation for an antenna a quarter wave high is 4dB stronger than for one at one-tenth wavelength high. Thus, optimum heights are 30 ft for 40M, 60 ft for 80M, and high angle radiation is only 1dB down for 45 ft on 40M and 90 ft on 80M.
http://k9yc.com/AntennaPlanning.pdf addresses this with a table and graphs. See Fig 36 and Table 1 on page 11.
73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
