Hi Gain Antenna - What is its best use?

I saw a fiberglass looking antenna, about five or six feet in length,
with a metal tip on one end.

I was wondering if there was a given length that would be good for
certain freq. ranges, and what applications something like this might
plug into.


TBerk

On Aug 12, 9:09*pm, TBerk <bayareab...@yahoo.com> wrote:
> I saw a fiberglass looking antenna, about five or six feet in length,
> with a metal tip on one end.
>
> I was wondering if there was a given length that would be good for
> certain freq. ranges, and what applications something like this might
> plug into.
>
> TBerk

I hope you are wearing flame retardant.

TBerk wrote:
>
> I saw a fiberglass looking antenna, about five or six feet in length,
> with a metal tip on one end.
>
> I was wondering if there was a given length that would be good for
> certain freq. ranges, and what applications something like this might
> plug into.

Impossible to tell...

Most likely you're looking at a co-linear antenna. Lower frequency
antennas are longer, higher gain antenna are longer. So you might have
a low frequency and low gain antenna or a high frequency high gain
antenna.

An 18 ft antenna at VHF 152 MHz is typically about 6 dB gain, at
UHF 460 MHz about 9 dB. A 5 to 6 ft antenna at 2.4 Gig and 5.8 Gig
could be anywhere from 10 to 15 dB.

On Aug 12, 10:38*pm, m...@sushi.com wrote:
> On Aug 12, 9:09*pm, TBerk <bayareab...@yahoo.com> wrote:
>
> > I saw a fiberglass looking antenna, about five or six feet in length,
> > with a metal tip on one end.
>
> > I was wondering if there was a given length that would be good for
> > certain freq. ranges, and what applications something like this might
> > plug into.
>
> > TBerk
>
> I hope you are wearing flame retardant.

While not intentionally Trolling, I am aware i can sometimes act in
the role of 'Big Spoon', stirring things up.

It isn't for dramas sake, and in this case I'll try and get more info
on this thing I saw in passing, perhaps post a link to picture in the
next few days.

TBerk

TBerk wrote:
> I saw a fiberglass looking antenna, about five or six feet in length,
> with a metal tip on one end.
>
> I was wondering if there was a given length that would be good for
> certain freq. ranges, and what applications something like this might
> plug into.
>
>
> TBerk

ok... simple background -

antennas are related to their frequency,
which in turn is related to their physical wavelength.

Just like grade school science - slap your hand in water = freq,
and the wave crests are the wavelength.... faster slap freq = shorter waves.

Given that - a shorter antenna is used for higher freqs,
and longer antenna is for lower freqs.
You can stack antennas inside a fiberglass pole to produce gain,
but that gain is omni all around the pole - like a donut.

Other antennas use a reflector - a dish - like a flashlight - to focus.

Sometimes the entire tower is the actual antenna,
like with AM radio stations, very low freq compared to CB, 2-way, Wifi

780khz AM vs 101.9mhz FM vs 27mhz CB, vs 150mhz/450mhz/900mhz 2-way
or 800mhz/900mhz/1900mhz for cellular phones,
and Wifi using same freq as your microwave oven at 2.4Ghz

SO... not sure what your real question is -

A fiberglass pole you happen to see could,
as was mentioned, be a single antenna for a low freq - like CB radios -
or a gain antenna like for police, fire, WiFi etc.

On Aug 14, 12:13*pm, Jeff Liebermann <je...@cruzio.com> wrote:
> On Tue, 12 Aug 2008 21:09:20 -0700, TBerk <bayareab...@yahoo.com>
> wrote:
>
> >I saw a fiberglass looking antenna, about five or six feet in length,
> >with a metal tip on one end.
>
> If the metal tip is pointed and kinda gold colored, it's made by
> Antennex. *If flat top and chrome, Maxrad. *If rounded and dull red,
> Antenna Specialists.
>

Flat Top, Chrome. Off white body, chrome bottom as well. A half doz
were sitting up in a fiber barrel at a surplus place, no real markings
or signage to describe what they were in detail.


> >I was wondering if there was a given length that would be good for
> >certain freq. ranges, and what applications something like this might
> >plug into.
>
> Nope. *The number of elements and their length determine the frequency
> and gain. *There are almost an infinite number of combinations that
> can be used, making identification rather difficult. *I've seen enough
> antennas that I can usually guess the maker and frequency. *Knowing
> the location, which identifies the user, might help determine the
> service, and thus the frequency. *However, just the length and the
> description is insufficient.
>
> --
> Jeff Liebermann


Alright, Thx for the info.

TBerk

On Aug 16, 4:34*am, Jeff Liebermann <je...@cruzio.com> wrote:
> On Fri, 15 Aug 2008 23:10:06 -0700 (PDT), TBerk
>
> <bayareab...@yahoo.com> wrote:
> >Flat Top, Chrome. Off white body, chrome bottom as well. A half doz
> >were sitting up in a fiber barrel at a surplus place, no real markings
> >or signage to describe what they were in detail.
>
> If there are no markings, the only way to tell is to crack one open
> and look inside. *If it's 5-6ft, it's probably a CB or marine antenna.
> The chrome bottom is most unusual and is not common among commercial
> antennas. *My guess(tm) is some consumer application like a cordless
> phone extender (46/49mhz), CB, marine, or something similar.
<snip>

What I'll try and do in the next couple of days is take a picture and
post a link online.

Considering my schedule, it might be a week from now.


TBerk

On Aug 17, 1:46*am, TBerk <bayareab...@yahoo.com> wrote:
> On Aug 16, 4:34*am, Jeff Liebermann <je...@cruzio.com> wrote:> On Fri, 15 Aug 2008 23:10:06 -0700 (PDT), TBerk
>
> > <bayareab...@yahoo.com> wrote:
> > >Flat Top, Chrome. Off white body, chrome bottom as well. A half doz
> > >were sitting up in a fiber barrel at a surplus place, no real markings
> > >or signage to describe what they were in detail.
>
> > If there are no markings, the only way to tell is to crack one open
> > and look inside. *If it's 5-6ft, it's probably a CB or marine antenna..
> > The chrome bottom is most unusual and is not common among commercial
> > antennas. *My guess(tm) is some consumer application like a cordless
> > phone extender (46/49mhz), CB, marine, or something similar.
>
> <snip>
>
> What I'll try and do in the next couple of days is take a picture and
> post a link online.
>
> Considering my schedule, it might be a week from now.
>
> TBerk

For the antenna to be resonant and a decent impedance match to your
wireless router it is going to have to be an odd multiple of 1/4 wl
long.
Since you say the antenna you are interested in has a metal tip I
assume it is adjustable witha screw that moves in and out a couple of
inches.
If you have the proper test equipment it should not be difficult to
adjusttthe antenna to the proper length.
The antenna will have a considerable amout of gain in the direction
of the axis of the antenna. Radiation perpendicular to the axis will
be pretty much nil.
IF you have the test equipment to tune it up and the radiation pattern
is what you want then go for it.


Jimmie

TBerk wrote:
>
> Flat Top, Chrome. Off white body, chrome bottom as well. A half doz
> were sitting up in a fiber barrel at a surplus place, no real markings
> or signage to describe what they were in detail.
>
>
asked & answered -

you're asking us to tell you what a plain paper box antenna has inside,
and what it can be used for ....

sorta like the "is this a good router" question -

if you don't understand all the details of this electronics stuff,
maybe you should not have a "client" just yet -