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Guest
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 Posted:
Fri Feb 11, 2005 2:54 pm Post subject:
Making FM Dipole Antenna |
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I live out in the boonies and it's hard to get decent Radio stations,
especially since I live in a home with metal siding and roofing. I
dont want to spend anything on this project, just use some of the odds
and ends I got laying around, and plan to put this on a board and
mount it outside with coax coming in the house.
I found the simple plans on this website.
http://www.northcountryradio.com/Articles/fmdip.htm
The only problem is that I dont have any of those ferrite rods or
toroids. However, I got one of those outdoor converter devices for tv
antennas that have 2 spade clips on the wires on one end, and a coax
connector on the other. (made to convert a tv antenna to coax). Can
I just hook the two wires from this converter to the two home-made
antenna wires and run my coax into the house?
And, just for the heck of it, I have an old busted tv antenna. Would
it work to use 2 of the "rods" from the antenna (length as shown in
the website), and screw them to a piece of plaxiglass in the middle as
an insulator? That way I can mount it on a nearby tree.
Thanks all
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Jerry G.
Guest
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| Posted:
Fri Feb 11, 2005 7:52 pm Post subject:
Re: Making FM Dipole Antenna |
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Antennas are tuned devices, and as simple as they look, they have to be
properly constructed. Get some books on antenna design and start from there.
The ARRL Antenna hand book is a good start. It is distributed by the Amateur
Radio Relay League. Your next step, will be to understand the contents of
the book.
The simplest antenna are a pair of wires cut to the proper length, and fed
down a properly matched coax cable to the receiver. At the receiver end, a
proper matching coil is used to match the antenna impedance, to the
receiver.
Your best solution, if you are not familiar with antenna design, and want a
fast working solution, is to go to the local Radio Shack and buy the
necessary pieces you need. This should work for you.
--
Jerry G.
======
<myself@no-email.com> wrote in message
news:oqro011eriol1i0s0pjpnbkt1emagdoe4j@4ax.com...
I live out in the boonies and it's hard to get decent Radio stations,
especially since I live in a home with metal siding and roofing. I
dont want to spend anything on this project, just use some of the odds
and ends I got laying around, and plan to put this on a board and
mount it outside with coax coming in the house.
I found the simple plans on this website.
http://www.northcountryradio.com/Articles/fmdip.htm
The only problem is that I dont have any of those ferrite rods or
toroids. However, I got one of those outdoor converter devices for tv
antennas that have 2 spade clips on the wires on one end, and a coax
connector on the other. (made to convert a tv antenna to coax). Can
I just hook the two wires from this converter to the two home-made
antenna wires and run my coax into the house?
And, just for the heck of it, I have an old busted tv antenna. Would
it work to use 2 of the "rods" from the antenna (length as shown in
the website), and screw them to a piece of plaxiglass in the middle as
an insulator? That way I can mount it on a nearby tree.
Thanks all |
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Guest
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| Posted:
Fri Feb 11, 2005 10:33 pm Post subject:
Re: Making FM Dipole Antenna |
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I figure you're talking about FM here. Here are some sites for that:
http://pages.cthome.net/fmdx/FincoFM.html
Here's a very good and complete one.
http://members.shaw.ca/weskyscan/Antennas.htm
I've built Yagis like this using copper water pipe or aluminum tube.
Solid copper wire is also ok. a board maybe not so good. plexi better
or really any plastic.
It helps to know where the signals are coming from or you could just
rotate the yagi to find the best signal.
Richard
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Mark Zenier
Guest
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| Posted:
Sun Feb 13, 2005 3:24 am Post subject:
Re: Making FM Dipole Antenna |
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In article <oqro011eriol1i0s0pjpnbkt1emagdoe4j@4ax.com>,
<myself@no-email.com> wrote:
| Quote: | I live out in the boonies and it's hard to get decent Radio stations,
especially since I live in a home with metal siding and roofing. I
dont want to spend anything on this project, just use some of the odds
and ends I got laying around, and plan to put this on a board and
mount it outside with coax coming in the house.
|
Search around on Don Lancaster's web site, www.tinaja.com or go back
a dozen years or so in Radio-Electronics/Electronics Now Magazine.
He had several columns where he wrote about his efforts to get some
distant FM station and had some interesting antennas.
Mark Zenier mzenier@eskimo.com Washington State resident |
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Isaac Wingfield
Guest
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| Posted:
Mon Feb 14, 2005 12:55 pm Post subject:
Re: Making FM Dipole Antenna |
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In article <oqro011eriol1i0s0pjpnbkt1emagdoe4j@4ax.com>,
myself@no-email.com wrote:
| Quote: | I live out in the boonies and it's hard to get decent Radio stations,
especially since I live in a home with metal siding and roofing. I
dont want to spend anything on this project, just use some of the odds
and ends I got laying around, and plan to put this on a board and
mount it outside with coax coming in the house.
|
In order to be effective, any antenna (except one with an amplifier in
it) must have elements about half a wavelength long, and if the signal
is really weak, the antenna will need several of those -- five to seven,
say.
The FM band is around 100 megahertz, where a wavelength is about three
meters. A set of meter-and-a-half rods is going to take a pretty big
"board" if you build it that way; most people don't.
Good FM antennas are around the same size as good TV antennas. Do you or
any of your neighbors have outside TV antennas? As a general guess,
whatever it takes for TV, that's what it will take for FM.
NOTE: TV channels 2-6 are below the FM band, and channels 7-13 are quite
a ways above it. The relation of those two sets of frequencies (about
three to one) is such that it's possible (and economical) to build quite
good VHF TV antennas that are *no good at all* for FM -- and that is
eaxctly the way most of them are made. Any antenna that is good for FM
as well as TV will definitely be so labeled, and if it's not, it
probably won't be. It's just about impossible to tell just by looking,
unless you're a real antenna guru.
Unless you really do want to learn a lot about antennas, you'll get what
you want for a lot less money if you just buy one; fifteen years ago
when I needed one, it was about $25-30 at Radio Shack.
Don't forget the ten-foot metal pole to get it up above your house (yes,
height matters, particularly because of that metal roofing. Twenty feet
might be better), guy wires to keep it from blowing over, and most
definitely a lightning arrestor and GOOD ground system. DO NOT install
any external antenna without one, if you value your electronic gear and
your house.
I'd use low-loss shielded 300 ohm twin lead to get the signal from the
antenna down to the receiver, and convert to 75 ohms there if the
receiver can't handle a300 ohm balanced input. Do the lead-in or the
impedance conversion improperly, and you can lose all the advantage you
gained from that high-gain, high-in-the-air antenna.
Side note: no matter how you do it, you must have a *much* stronger
signal for stereo than for monaural -- about thirty dB better, in fact.
If the signal is not strong enough, you'll get a lot of "hiss" when you
switch to stereo that goes away when you select mono.
Isaac |
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