Back about 10 years ago - I played around with a parasitic element and had good results.
One method I used to determine how well - and where the antenna worked was to use a wide band noise source. You can build one - or I know Elecraft has one. For long distances - I would use my amplifier to make it louder (only do this during the daytime). You can then put a receiver on the back side of the antenna and quickly find the frequency where you have the best rejection (front-to-back). I feel the main drawback of the parasitic elements is that they work over a pretty small portion of the band. This is probably okay for DX work - but if you are doing contests and need to go up the band some, your performance will quickly drop off. Tree N6TR On Mon, Jan 29, 2018 at 10:40 AM, N7DF via Topband <[email protected]> wrote: > > From southcentral New Mexico working Europe on 160 meters is pretty much > an exercise infrustration with a single vertical antenna. So I decided to > see if I couldimprove on things by adding a parasitic reflector element to > my cage antenna. Since I could not find any specificinformation about > doing this I decided to experiment a little and see what Icould come up > with. After looking at a lotof designs for two element antennas and taking > into consideration the physicalparameters of being in a juniper forest I > finally came up with a design that Icould build. My antenna is a > Collins27W-1X conical monopole fed with an MFJ 998 remote tuner located in > a 120 footdiameter clearing. The parasitic reflector would be 88 feet > southwest of the monopolein a small clearing. From what I coulddetermine > from various sources, in order for it to be effective at thatdistance, it > would need to be resonant at 1.787 MHz to provide maximum gain at1.825 > MHz. The reflector elementconsisted of a 30 foot tall section of 2 inch > diameter irrigation pipe restingon a plexiglass sheet with a top hat wire > strung at right angles to the linebetween the transmitting antenna and the > reflector. In the opposite direction a ground radial waslaid out along the > ground surface. Aftera lot of measuring with an antenna analyzer and > cutting to length the top hatwire ended up as 86 feet 4 inches long and the > ground radial at 112 feet 3inches to get resonance at 1.787 MHz. The bottom > of the vertical is connectedto the ground radial with a clip lead so it can > be taken out of the circuitwhen I want the monopole to be omnidirectional. > The array turned out to be veryeffective in changing the pattern of the > monopole and there is a markedimprovement on signals from the northeast > both in North America and from Europeas realized in the recent 160 meter > contest. The best measure, though, turned out to be courtesy of WD5COV who > isabout 125 miles southwest from me. Hissignal is usually about 40 over S9 > when he has his 4 square pointed myway. After installing the > parasiticelement his signal dropped to about 20 over S9 on peaks. > Unfortunately the antenna has not improved mynoise problems but that is > another story. > N7DF > _________________ > Topband Reflector Archives - http://www.contesting.com/_topband _________________ Topband Reflector Archives - http://www.contesting.com/_topband
