antenna-theory.com

[JerryJ]

Hi Folks: New here

I have a back ground in ham radio and have built a few home brews, mostly sucessful but have encountered the odd flop, just by experimenting.

My question is:

I want to build a multi-band RX (only) antenna that would capture the same as a Discone. Many told me just to go buy a new discone. How easy is that? IMO that certainly takes away from the hobby of learning designing and building. Would I save any money? Who knows and in some cases who cares !!! ???. It's like a long trip. Is it the destination or the trip itself? So now you know where my intention is.

I'm planning on building a simplified version (based on MY design) of a multiband RX antenna that covers VHF, UHF, 220MHz and 900MHz trunking.

Aside from creating element that may be "fatter" to allow a more broadband capture, my question would be how much spacing between elements. Is there a hard and fast rule via formula.

I can understand gain between elements for a yagi whether for TX or RX but for simple local RF reception (local means within 50+miles).
But how close dare I place elements? I'm also planning on image or counterpoise
Thanks for any help

[JerryJ]

I'm just redefining my question
Since this is only an Rx antenna, with never any intention of Tx, I realize that not so much is critical. However, I want to do the best I can for the design prior to build.

If I use metal rods, copper, aluminum, for example, "touching each other" then we know that the elements in essence would become one "solid mass"
If, in theory, I have a series of plastic coated wires acting as those vertcial elements, touching each other, while they may be isolated and insulated, I sense their proximity to each other may be too close. And, that is where my question beigins. How much separation from each other should they be? Or, does it really matter, as long as they are separated?

I suppose one of my main reasons for asking this question is to allow my Rx antenna to be considered being a 50 Ohm antenna, used with a 50ohm transmission line (RG58) and the reciever itself
Thanks