How do i make an FM radio antenna?

[chiwawa626]

I finaly got my tv tuner working properly agian, and i want to get better FM reception on it. I heard theres an optimum length and stuff for antennas to get best reception...Any sites or ideas? The station id prolly be listening to most is 94.9 FM if that helps?

 

[notfred]

1 wavelength at 94.9 mhz would be ideal. Followed by half wavelength, then 1/4 wavelength. To find a wavelength, figure that waves travel at the speed of light, and you have 94.9 million wavelengths per second.

 

[chiwawa626]

I forgot all my physics, so in english that means my antenna would be ____ shaped, ____ long, and made out of ____.

 

[notfred]

Try this:

Here's a link

 

[sohcrates]

buy a cheap fm antenna (unpowered) at radio shack.

or just get a lenth of wire and cut it until station comes in good.

not too complicated really

 

[conjur]

chart of some wavelengths

 

[ultimatebob]

Geez, whatever happened to just unbending a coat hanger and using that as an antenna? It worked miracles when I was a kid!

 

[Analog]

best to match impedances, so check what you have (75 ohm? 150 ohm?). Use a piece of matched coax to an arial, and based on your frequency, the wavelength is 3.16 Meters. So extend a wire horizontally in one direction at half that length, and in the other direction the same. FM transmission is polarized in both the horizontal and vertical plane, so it doesn't matter the angle of the wire once extended. But you may try rotating it to get the best reception. BTW, 94.9 is my favorite frequency out of Lansing, MI>

 

[Antisocial Virge]

Originally posted by: ultimatebob
Geez, whatever happened to just unbending a coat hanger and using that as an antenna? It worked miracles when I was a kid!

Gone high-tech now, steelwool is involved.

 

[ScottMac]

A dipole antenna is a half wavelength end-to-end. each leg should be 1/4 wave.

A basic FM antenna is ~4 ft of 300 ohm twinlead. cut ONE conductor in the middle and strip the cut ends ~1/2 inch. Use another length of twinlead to descend to the tuner (a 300-to-75 ohm adapter should be used to connect to the FM input of the tuner).

You could use coax (50 ohm - RG/59 or RG/6) to make the connection to the antenna. There's a 4:1 impedence mismatch, but it's not really gonna matter much.

Soldering is recommended, but anything that give you a good physical connection will work OK.


Possibly easier:

Use a length of coax (RG/59 or RG/6). The length should be ~4 feet + the distance to the tuner.

Strip off ~ 2 - 4 ft of the outer jacket. Pucker the braid at the beginning of the jacket (the end that goes to the tuner) and pull the center conductor through the hole made in the pucker. The center conductor is one leg of your dipole, the braid is the other leg. You don't have to strip the center conductor. It's still a 4:1 impedence mismatch but you don't have to deal with soldering or joining two pieces of cable or using an adapter.

Good Luck

Scott

 

[Gillbot]

Tin Foil

I just use an old set of rabbit ears!!

 

[JOSEPHLB]

I dont know how many freaking times I've wrapped tinfoil around my set of rabbit years to pick up a football game back when I was younger..