Showing posts with label qth. Show all posts
Showing posts with label qth. Show all posts

Friday, November 21, 2008

QTH part 2: Bird's Eye View




Here's a diagram of my lot. North is to the bottom. Existing antennas are shown in red (click on the diagram for an enlarged version).

The lot is about 90 feet wide by 70 feet deep. It's a corner lot (the corner is at the lower left of this diagram).

One major issue is that the electrical service in our neighborhood runs through everyone's backyard, instead of being along the street. Our service comes across our back yard diagonally and enters through the garage. This means that I can't use any antenna supports in the right-rear of the house. Any new support structures will need to be to the rear and the east (left side of the drawing - to the left of the G5RVjr in the photo).

Some of the ideas I've thought of are:
  • A multiband vertical mounted where the G5RV feedpoint is now. It will be difficult to attach a decent set of radials, since this is 11 feet from the rear of the property.
  • Some sort of roof-mounted vertical. It would be easier to create a good radial field in that case, but the antenna will be pretty visible. There are some "no radials required" verticals (I guess they're really vertical dipoles) but I'm not sure how well those would perform).
  • A small mini-beam on some sort of mast/tower that can be raised/lowered when not in use. For example, the Butternut HF5B seems like it could be parked down at the lower roof line so that it would not be visible from the front of the house. The mast/tower for this could go at the rear of the house, about 10 feet to the left of where the G5RV is now.
  • A ground-mounted vertical in the front or side yard, disguised as a flagpole.
  • A BiggIR vertical:
    • Ground-mounted with an adequate radial field in the front or side yard.
    • Roof-mounted with a set of resonant counterpoises.
  • Extending the 40M vertical and turning it into a multi-band wire vertical.
  • Tower + beam: I think this would be a tough battle to fight, but maybe...
Any other ideas?

Overview: My QTH, part 1



Here's some information about my QTH.

First, here's a photo from the front of the house, looking south. I've drawn some red lines to show where the current antennas are.

At the left (in the Gingko tree) is a 40M 1/4 wave wire vertical. The feed point is in the lowest crotch of the tree, about 5 feet above the ground. At this time, there are 6 radials that run down the trunk and fan out in the front yard. Since the tree is up against the sidewalk, the radial field is not symmetrical, and this does perturb the radiation pattern (I'll include some EZNEC plots in a subsequent post). As I mentioned in a previous post, this antenna seems to work fairly well on 40M and 15M, and I made about 180 contacts using it during the 2008 Sweepstakes.

Above the house is a G5RVjr mounted on a mast attached to the chimney of the house. I recently installed this, and it generally doesn't perform as well as I'd hoped:
  • On 40M, it picks up a lot more noise (local, I assume) than the vertical, and signals seems to be about the same level.
  • On 20M, it seems to work, but I think it's up high enough that it exhibits a typical dipole pattern (e.g. not NVIS) and therefore there are nulls off to the east and west. It seemed to work well for stations to the north and south, however.
  • On 15M, stations to the north were better on the G5RV, and stations to the east were better on the vertical.
So that's what I have today. Next I'll post an overhead drawing of the lot.