Long wire antennas?

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George Oakes:
I am in a 2 story appt. I can get into the attic, but the complex recently replaces the asphalt shingles for new "Tin" roof on all the buildings.

So an antenna in the attic is now out of the question.
I have a nearby tree that I could probably get some Thin wire into for a fairly invisable long wire.

I have an antenna tunner, and I know I could use a long wire, my question is this.

Is the entire length of the wire the radiating element?
if so, if it touches the "tin" roof will that be a problem.? can I use insulated wire, till I clear the roof, and then go with the invisable stuff? i was thinking 26 guage magnet wire? for the rest of the long wire?

I am fairly new to the concept of long-wire antennas, and I dont know all the properties of this type of antenna.

thanks a bunch

Steve Katz:
I'd make the whole wire antenna from insulated wire, and pick a color that blends in best with the background, whatever that is.

#26 magnet wire is unlikely to last very long outdoors because it's not strong.  A large bird like a crow flying into it, or finding it a challenging place to roost and have some friends over for a visit (yielding several crows all trying to balance on the wire, which they are absolutely amazing at doing) is very likely to simply break the wire.

If the far end is supported by a tree limb or branch, the first windstorm that flexes that limb is also likely to snap the wire, unless the wire has a lot of slack in it to begin with; and the problem with a lot of slack means the wire is hanging down and more visible than a taut wire would be.

An end-fed wire antenna also needs a second conductor for RF return current.  Usually, that's "ground," and an RF ground on a second story of a building can be difficult to achieve, so you might need a second wire, maybe one running around on the floor inside the apartment and connected to the tuner chassis, to make the outdoor wire work.

If an end-fed wire seems the only option, I'd go for about #20, insulated, with a dark color insulation.  It will be a lot stronger than #26 and more likely to survive birds, wind, etc.

WB2WIK/6

Bob Lewis:
Yes, the entire length of the wire from where it exits the tuner will be the radiating element. It will be a problem if it touches the tin roof. Insulated wire will help but if very much of it is laying on the tin roof then you will still have capacitive coupling into the roof. The farther you can keep it away from the roof, the better.

An end fed wire will always need an RF ground or counterpoise of some type at the tuner. Otherwise the tuner and radio case will be "hot" with RF.

Just a thought - if you had an automatic tuner (an SGC for example) that you didn't have to access to tune then perhaps you could place it in the attic. The counterpoise could be the tin roof if you can make a short connection to it. Then feed the wire with the tuner output thru an insulator in the soffett or something (to keep it away from the tin roof as much as possible). The pieces that make up the tin roof probably don't have a super good electrical connection between them but there may be enough overlap to provide some good capacitive coupling. Make sure the piece you connect to is as large as possible.

Bob Macklin:
I have a similar problem.

I am in a 4th floor senior complex. No outside antenna possible. So I am currently recieveing with a 33ft wire run around the wall just below the celing. That seems to work reasonably. But it is the best I can do in this apartment. This is a wood frame building but I don't know about the insulation in the wall. It may or may not have aluminum covering.

And I don't have access to metal water pipes for a ground. I have been looking at a MFJ antenna tuner with the tunable counterpoise. How well does that work?

My bigger problem is TVI. My 2M FM tranceiver blocks my TV. I suspect it is probably getting into all the adjacent apartments. I have not tried fixing that problem yet.

Bob Macklin
K5MYJ/7
Seattle, Wa.

Howard Barnes:
Although I have never tried them, there are two antenna designs I read about in one of the Yahoo groups that are useable inside an apartment.  One is a "broomstick antenna" with about 200 ft of insulated wire wound around a long pvc pipe or broomstick.  This antenna sometimes has a metal pie plate "hat" at the top end of the stick.  Another design is a "slinky" dipole that can be hung inside the apartment.  Use the original style metal slinky toy as each end of the dipole -- you can solder more than one slinky together to create a longer antenna.  The metal roof you described would probably interfere with propagation -- you may want to hang the antenna on an outside wall to maximize radiation.

Just some possibilities.

For what it's worth,
Howard

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