Homemade Dipole

[Trotter70]

Hi Guys,

Ive read a couple of things about the homemade dipoles,

my question is do these antennas work if you use them vertically in an attic, across the top beam for example

as an alternative to having a large Ariel in the garden or on the house.

if they do work and its worth doing does any one have a link to build one please?

I've only just returned to radio after 35 years so I'm not up to speed so any help much appreciated.

Thank you
Paul.

[ghost123uk]

Hi Paul,

It's certainly worth a try, especially as it will be free, as in, all you need is about 18.5 feet of wire (for 11Mtrs). There is no "building" to do really. Just string it up, connect the centre ends (neatly) to the coax (see note below re "ugly ballun") and trim the ends until the SWR is good.

my question is do these antennas work if you use them vertically in an attic, across the top beam for example

Do you mean vertically? as in standing 18 feet tall? because you say "across the top beam" which to me makes it horizontal, unless I am misunderstanding you (which is quite possible).

A horizontal aerial is always going to be directional, as in, won't receive well from its "ends" direction.

If you do go ahead with a Dipole, then, at the feed point, it's a good idea to fit an "ugly balun" (Google it) consisting of 5 turns of your coax feeder wound neatly and as close together as possible around a 4" diameter bit of plastic pipe. The bare ends at the top of the coil attach to each of the centre ends of your dipole. This makes sure all your RF gets to the dipole and is not radiated from the feeder. Well worth doing, especially as it's so cheap (as in free) and easy to make.

Depending on the space available in this roof area, consider a home made "ground-plane" consisting of a "spokes of a wheel" type arrangement of copper wires (the more, and the longer, the better), all joined to a metal plate at the centre ("hub") with a home made loaded 1/4 wave vertical aerial in that centre place, obviously with the actual aerial isolated electrically from the ground-plane.

If you need any more detail, shout out.

[Trotter70]

Thanks for that,
yes i meant horizontally sorry, but i think you have confirmed what
i suspected which is it would make it directional which is no use really,
looks like back to plan A and get a sirio gain master.

thanks for your input.

[Buick Mackane]

An inverted V is another option, See link below.
http://www.hamuniverse.com/dipivcal.html

[2E1IIP]

You may also want to consider a Halo which is a folded half wave into a square configuration so would only need a 4 foot square footprint.
This will give a reasonable omni-directional pattern horizontally polarised.
You will need to match it using a variable capacitor and inductive tap to be able to use it with 50 ohm coax feeder.