Now that the leaves are off the trees and the cold weather has returned it's time to do antenna work.
I have an inverted L between two trees with 34 radials on the ground. Four radials are 135 feet long, the rest 70 feed long. I choose these lengths because they fit my yard. During the summer I keep the radials in the wooded area of my property in an arc of about 210 degrees. Once the leaves are off the trees I spread the radials into a full 360 degrees. I normally measure the feed impedance with my N2PK VNA with requires lugging a laptop along with me. I built a FA-VA5 Antenna Analyzer. While cumbersome to used standalone it is battery powered and quite handy. My Inverted L is longer than a quarter wavelength on 160. I also use it on 80 meters and don't have to worry about matching a high impedance. I wanted to see what effect changing the radial field diameter. I measured at the resonant frequency, 160 and 80 meters. Here are my results: 210 degree radial field: Freq(MHz) Rs Xs 1.62 21.2 -1.7 (close to resonance) 1.8 30.7 +112 2.0 46.5 +237 3.5 111.0 -654 4.0 65.6 -346 360 degree radial field, relocated 7 radials. Freq(MHz) Rs Xs 1.62 16.7 -5.6 (close to resonance) 1.8 23.6 +107 2.0 36.4 +233 3.5 124.0 -661 4.0 59.7 -351 I wanted to move more radials but unfortunately they are stuck under a frozen leaf cover. I'll get to these when it warms up. I was surprised that moving just a few radial made such a difference. Mike N2MS _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
