Thanks,

Great info!

So you could take that 8.25cm wire and wrap it into a coil and it would be
just about as effective as leaving it straight?

Can I use just normal stranded ~24AWG hookup wire for the antenna?  Does
the insulation around the wire matter?

Thanks,

Gary

At 09:25 AM 5/14/2002 -0700, you wrote:
>Antennas are a whole subject in itself. They come in all sizes, shapes, and
>colors. Simply put, a monopole is a simple antenna which is a single piece
>of wire, usually called a whip in most forms. Antennas should be tailored to
>the frequency being used. Moreover, they need to be tuned to listen in for a
>specfic frequency's wavelength or a function of it.  Depending on the
>frequency and type of usage, there are different antennas for different
>applications. Higher frequencies tend to be more directional as you go up in
>freq which creates the need for antennas that can transmit or listen in all
>or specified directions.
>
>A 1/4 wave antenna works fine for most applications. Use this relation to
>figure this out required length:  C= lamda x V, where c= 3 x 10^8, V =
>frequency, and lambda = wavelength.
>
>For example, a 900MHz device would need:
>
>3 x 10^8 / 900 x 10^6 = .333 meter wavelength. Dividing this by 4, only a
>8.25 cm long antenna is needed. This can be a loop, coil, etc.
>
>Linx technologies has a good primer on antennas.
>http://www.linxtechnologies.com/ldocs/pdfs/AN00500.pdf
>
>Also, they have an antenna site.
>http://www.antennafactor.com/adocs/f_prod.html
>
>Hope this helps,
>Michael
>
> > [Original Message]
> > From: Gary Neal <gln103@PSU.EDU>
> > To: <PICLIST@MITVMA.MIT.EDU>
>  > Date: 5/14/02 8:57:12 AM
> > Subject: Re: [EE]: RF modules
> >
> > Guys,
> >
> >          Recent discussion has peaked my interest especially since the
> > relatively cheap Laipac modules were introduced.  I'm looking at using the
> > TLP434 modules outside in an open field.  I'd like to get the most range
> > that I can.  At least 150' but would be nice to get to ~600'.
> >          Anyway, I have no experience with RF, specifically the
> > antenna.  Can someone shed some light on this?  How do you know how long a
> > wire to use?  Do you just use a piece of wire?  What gauge?  Can it still
> > have the insulation on it?  What is "loop", "whip" style that I see listed
> > on the Laipac page?  Is the antenna different for the transmitter and
>receiver?
> >          As you can see, I'm a novice at this antenna stuff.  I don't
> > really want a whole bunch of analytical antenna design mumbo jumbo.  Be
> > nice if someone would say something like "Ya, just connect a piece of
>24AWG
> > wire to the antenna that's about 3" long and that'll give you pretty good
> > reception".  Something like that.
> >
> > Thanks,
> >
> > Gary

Gary Neal
Research Assistant - Drivetrain Technology Center
Applied Research Laboratory - Penn State University
PO Box 30
Research Building West
North Atherton Street
State College, PA 16801
814-863-5468 (phone)
814-863-6185 (fax)

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