About

My name is Russell Roberts and I am the administrator of “KH6JRM’s Amateur Radio Blog” (http://kh6jrm.com).  I am the retired news director of Pacific Radio Group stations on Hawaii Island.  I am also a retired Lt. Col., USAF Reserve.  I have been a FCC-licensed amateur radio operator since 1977, holding all classes of amateur radio license–novice, technician, general, advanced, and amateur extra class.  My particular interest is the designing, building, and erecting of stealth or hidden antennas.  I have lived in areas where amateur antennas were either prohibited or severely restricted by lack of space and proximity to utility lines.   I gained most of my antenna knowledge through my military career and almost 40 years of broadcast engineering at both commercial and university (student) radio stations.  Now that I am semi-retired, I can devote more time to my amateur radio interests.  My wife and I spend our retirement years as substitute teachers for the state of Hawaii Department of Education.

I am always looking for new antenna ideas. If you have any antenna projects that have turned out well, please share them with our blogging community.  I welcome your input.  The journey continues.

Aloha, Russell Roberts, KH6JRM

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2 Responses

  1. Please send me information about NVIS. I have a mystery antenna 10 thru 160m and want to know how to set it properly, my email is kd8cee@gmail.com. Heights from center and ends. Currently 30 ft. center to 6 ft. ends.
    Thanks in advance, 73,
    Dan KD8CEE

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    • Greetings from the Hamakua Coast of Hawaii Island! NVIS (near vertical incident skywave) are ideal for local communications out to about 200 to 300 miles. Most of the radiation from these antennas goes straight up, thus giving the antenna the name of “cloudwarmer” or “scatter beam.” The military has been using this type of antenna for decades to maintain reliable, strong regional communications. According to what I’ve read, the radiating element should be between 15 and 20 percent of a wavelength above ground. For 40 meters, a NVIS should be anywhere from 19 to 26 feet above ground. My 40 meter NVIS is only 10 feet above ground and it works very well for local (200-300 miles out) contacts. The signal enables me to join a daily 40 meter net without having tall mountains interfer with the signal. The signal goes straight up, clears the mountains, and drops into the many valleys common in the state of Hawaii. Your design should work well even at a low height for 160 meters (24 to 46 feet above the ground). A reflecting wire under the main element will add extra punch to the signal. You will probably experience a lower noise level than a regular dipole erected 1/4 wavelength above ground. There are several good articles explaining the NVIS phenomenon. My favorite can be found here:
      “Understanding Amateur Radio NVIS Antennas and Propagation”, Harold Milton, KV5R, http://www.athensarc.org/nvis.asp. I hope this helps. Aloha, Russ, KH6JRM

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