Electronics > Beginners

FM antenna

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fixit7:
It picks up some FM stations but not many that don't fade in and out.

https://www.dropbox.com/s/i1hhzwj7kgr0n7y/RadioAntenna.jpg?dl=0

richnormand:
Before going too complicated see if your receiver has a 300 ohm input for the antenna.
If so, it is easy to fabricate an antenna with simple 300 ohm twinlead lines. It can then be taped to a window or the ceiling.
If your receiver only has a coax input (75 ohm ) a simple balun will change the balanced 300 to unbalanced coax at 75 ohm. They cost only a few dollars.
http://users.wfu.edu/matthews/misc/dipole.html


It may not be the best but it is easy to conceal in an unobtrusive spot (if you want, I have not :-DD).
Here is mine in my workshop in the basement. Works very well. Depending on the weather I sometime have to move one arm to a different angle with a thumbtack.
The antenna is about 150cm long but was designed for TV. If I remember correctly FM is located between the old channel 6 and 7 in US Canada if you want to use the table in the link.
At any rate if you are about to change the angle between the two legs for best reception this should work fine.


ocw:
Whatever antenna that you use, you will have much better reception the higher and more in the clear that it is placed.  If it has to be inside, keep it away from computers and cheap switching power supplies.  Some of the switching supplies used with LED lights have measured harmonics up past the FM broadcast band.  And if the supply is not built into the bulb, the connecting cable becomes a good transmit antenna.  Some traffic lights with supplies in their support poles wipe out weak signal reception near them.  I have seen the same happening with inside lights.  One person complained about bad reception only at night.  I said to watch for outside lights coming on--they soon found that as the source of their problem.

I wouldn't expect much benefit from using vertically stacked elements of the type shown INSIDE.  A single element near the ceiling (without electrical wires above it) might work better.

fixit7:

--- Quote from: richnormand on May 27, 2019, 08:05:19 pm ---Before going too complicated see if your receiver has a 300 ohm input for the antenna.
If so, it is easy to fabricate an antenna with simple 300 ohm twinlead lines. It can then be taped to a window or the ceiling.
If your receiver only has a coax input (75 ohm ) a simple balun will change the balanced 300 to unbalanced coax at 75 ohm. They cost only a few dollars.
http://users.wfu.edu/matthews/misc/dipole.html


It may not be the best but it is easy to conceal in an unobtrusive spot (if you want, I have not :-DD).
Here is mine in my workshop in the basement. Works very well. Depending on the weather I sometime have to move one arm to a different angle with a thumbtack.
The antenna is about 150cm long but was designed for TV. If I remember correctly FM is located between the old channel 6 and 7 in US Canada if you want to use the table in the link.
At any rate if you are about to change the angle between the two legs for best reception this should work fine.

--- End quote ---

My radio has a 75 ohm coaxial connection and one for a loop antenna for am.

richnormand:
Then a simple balun will work for you.
https://skyviewelectronics.com/tv-antenna/300-75-ohm-transformer-video-balun-0
They are bi-directional.
Also available much cheaper in the US.  The link provided as an example is in CDN $.

Also noted on your previous post (reply #10) a photo showing the antenna but with a Venetian blind on the window. If it is made on metal it could affect your reception greatly depending of Tx and Rx geometry. Does the signal change if you roll it full up?

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