[amsat-bb] Re: TransAtlantic Balloon on 28 MHz ?

[John Magliacane]

--- On Thu, 2/16/12, Roger <Rogerkola at aol.com> wrote:

> CB uses vertical beams...the difficulty is that they have to have
> a non metallic mounting pole extending into the beam or be end
> mounted (think torque)

The mounting pole may contribute some capacitive or inductive loading effects on the elements adjacent to it, but a smart antenna designer can modify the antenna's element lengths to compensate for these effects.

The pole itself will have a negligible effect on antenna performance, unless it happens to be resonant (or very close to resonant) at the operating frequency.  Otherwise, it's essentially transparent.

> On 2/16/2012 12:18 AM, Bob Bruninga wrote:
>
> Just wondering if anyone has a vertical beam.

If the signal is strong enough (and/or the receiver sensitive enough), an electrically small loop antenna can be used for 28 MHz radio direction finding purposes.

A vertically oriented loop will respond to vertically polarized RF.  (In reality, it's responding to the horizontally polarized H-field).

The ARRL Handbooks and Antenna Books have carried designs regarding 28 MHz RDF antenna for many decades.


73, de John, KD2BD