5 ghz antenna

Can you use a 5 ghz antenna in the 2.4 range and what will happen to gain.
Thanks Ed

> Can you use a 5 ghz antenna in the 2.4 range and what will happen to gain.
> Thanks Ed

Depends on the design, but it probably won't be a good experience.

Antenna designs can be scaled in frequency, allowing you to take a design at
1 MHz and simply scale it up to 10 MHz, and so on, but for an antenna to
operate on two bands so far apart, takes special attention, or luck. A half
wave dipole for instance, becomes a full wave dipole at twice the original
frequency, and that isn't a bad thing. A full wave loop becomes a two wave
loop though, and that IS a bad thing.

On Mon, 24 Jan 2005 13:34:47 -0500, "Ed Williams" <(E-Mail Removed)>
wrote:

>Can you use a 5 ghz antenna in the 2.4 range and what will happen to gain.
>Thanks Ed

In general, it won't work. You'll have high VSWR (reflected power),
lousy gain, crummy radiation pattern, and a huge waste of time and
effort. This isn't universally true as there are some very broadband
antennas that will work on both bands.

So, what are you trying to accomplish and what do you have to work
with?


--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 AE6KS 831-336-2558

Ed Williams wrote:
> Can you use a 5 ghz antenna in the 2.4 range and what will happen to
> gain. Thanks Ed

Generally one made for only one frequency/band won't work very good, however
they do make a few "dual band" antennas, for WiFi stuff that does both 2.4
and 5.

Think of it in more common terms..(not technically exact, but hopefully
similar enuf to make sense and be understandable) They make VHF TV antennas,
but if you try and use em for UHF, they sortof work-but not very good,
however, they do also make combo VHF-UHF antennas, and those work pretty
good in the correct bands.

"Dave VanHorn" <(E-Mail Removed)> wrote:
>> Can you use a 5 ghz antenna in the 2.4 range and what will happen to gain.
>> Thanks Ed
>
>Depends on the design, but it probably won't be a good experience.
>
>Antenna designs can be scaled in frequency, allowing you to take a design at
>1 MHz and simply scale it up to 10 MHz, and so on, but for an antenna to
>operate on two bands so far apart, takes special attention, or luck. A half
>wave dipole for instance, becomes a full wave dipole at twice the original
>frequency, and that isn't a bad thing. A full wave loop becomes a two wave
>loop though, and that IS a bad thing.

A full wave dipole is a *very* bad thing! The feed point
impedance won't be anything like a half wave dipole... instead
of a low impedance like the half wave dipole, it will be
extremely high.

A half wave dipole, however, will work just fine at any *odd*
multiple of the design frequency. Of course, the raditation
pattern is not the same at any of those odd multiples, so if it
is oriented correctly for any given direction at one frequency,
it won't be at any of the other multiples in frequency.

To put it mildly, "takes special attention" was the operative
phrase!

--
Floyd L. Davidson <http://web.newsguy.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska) (E-Mail Removed)