Part 3- some notes on the parasitically enhanced vertical


Jeff     VE1ZAC

Sept 2007


I have mentioned several times that I have a less than ideal location for RF activities. I am in the city of Halifax, about a Km. from the harbour’s salt water, about 100 feet in elevation, on loose pyretic slate rock and granite with almost no soil to speak of. On top of that the antenna is stood up against  a garden shed full of metal objects, there is an aluminum boat parked right in front about 8 feet from the antenna, a 12 foot steel basketball post is 6 feet away and a 50 ft feed line for one of my windoms is about 20 feet away.  That’s pretty much everything on the “Don’t Do” list. Yet, this thing still works. With less than ideal radials too. I have maybe 4 for each band tossed on the ground and not very symmetrically placed. The point is… it doesn’t have to be perfect to work, or be an improvement over some other antenna option.  It is often worth the effort to lash something up and give it a whirl.

Here is the model with the steel post and windom feedline in play with 30M currents. You can see there is little effect on the antenna’s current distributions.















Here is the matching device at the base of my antenna, and a sketch of the matching circuit I use for 80,40 and 30M. The 1:1 UNUN is now a switchable 4:1 UNUN.




























Now for the dimension sketch:



Note: these dimensions are particularly dependent on my antenna and location. If you try this, without modeling, allow adjustments in the geometry and monitor the feedpoint impedance for a good “Dip” where the Yagi effect develops. Personally, I think it’s easier to model the thing and then cut wire. Caveat Emptor.


Working the ether :  Last night the 3B7C operation was on in full swing. I monitored for a while. 20M was weak but possibly doable with the Stepir beam, 30M and 40M were pretty fair and 80M was pretty fair.  The vertical was the best listening antenna for 30 and 40. The windoms brought up a lot more noise and a lot more hams in the US and Canada calling 3B7C. The switch to the vertical ( array, as I guess it should be called) was pleasing to my ear. Called  with 30M  and 100 watts… bang, second call. That was cool. Called on 40M with 100 watts for an hour… nahda. Amp comes on.. 300 watts to antenna, and got through.

Kept trying 20M and 80M with other antennas, power ( my little homebrew amp can do up to 600 watts out.) and no power.. no luck. Well, looks like Mr. Vertical array was the right thing for the job !


“To infinity…. ….And beyond !  ( Buzz Lightyear)