AboutChris Bushman Expertise I have been an amateur radio operator for about 36 years.
Experience In real life I manage a small motion picture film lab in Hollywood. I've been a fireman, a teacher of English in Okinawa, a personal computer tutor.
I am an Advanced Class Ham radio operator using my originally issued callsign WB6EEQ. I have operated for extended periods of time from Okinawa (KR6FX & KR6OP), Texas (K5VXG), and Mississippi (K5TYP).
While in the Air Force, I was a Manual Morse Radio Intercept Operator.
BS Zoology, UC Davis
Member, Society of Motion Picture/Television Engineers http://www.smpte.org/ - Member, American Radio Relay League http://www.arrl.org/ - Member, Quarter Century Wireless Assn. http://www.lockport-ny.com/radio.htm - President, Zen Nippon Airinkai, So Cal Chapter http://ourworld.compuserve.com/homepages/Chris_Bushman/ - Member, Maltose Falcons Homebrewing Society http://www.westval.com/mfalcons/ - Alumni, American Brewers' Guild http://www.abgbrew.com/
Expert: Chris Bushman Date: 1/18/2008 Subject: antenna location
Question Hi, Chris.
I'm contemplating the installation of a Butternut vertical antenna on my 1 1/2 acre lot, which is moderately wooded with oaks and maples. I'm torn between mounting it on the roof of may house--something that my wife would frown upon---or mounting on the ground in the woods and burying the radials under a layer of mulch. The latter would require a run of about 150 feet of transmission cable. Though I've read dozens of articles on the subject, the question of RF absorption from trees and length of the antenna transmission line is hardly addressed. Would you mount it on the roof and risk marital strife and tribulation, or would you mount it in the woods? What would you consider too long a transmission cable and what kind would you use? Your thoughts are appreciated!
Thanks,
Jim
Answer Well, Jim, if it were me, in order to avoid celibacy, I would mount it on the roof with a flag on top that said, "I love my wife!!!" What spouse could complain about anything so romantic?
...but if you want to wimp out and plant it on the lawn, here are a couple of thoughts.
Use the lowest loss coax you can afford. RG-8 is probably a good compromise between RG-58 and RG-218. (loss for 150' at 10mhz is 2.1db for RG-58; .6db for RG-8; .23db for RG-218). Losses are lower at lower freqs and higher at higher freqs.
Make sure your connectors are put together really well. Good solder connections and no melted dielectric insulator. If you have to go 150 feet, make the coax all one piece. No fair using three fifty foot pieces joined together.
Have you considered mounting it on top of a short tower or out building? If you mount it above ground, you can adjust the angle of the radials to adjust the impedance. I don't know if it applies to a Butternut, but a simple quarter wave spike adjusts out to 50 ohms at something like a 45 degree radial angle.
You might want to keep things loose and experiment with different setups. Even the conductivity of the soil counts a lot. Maybe that side of the house would work better than this side of the house.
Trees are such a big variable, I'm not surprised that it is rarely addressed in articles. Suffice it to say, they will interfere with the radiation pattern of the antenna, but the extent of that disruption could only be determined by measurement in your particular situation, with your particular trees.
