FM antenna - Page 1
Forum section: electronics / beginners

author: fixit7
author_rank: Regular Contributor
timestamp: May 27, 2019, 01:35:18 pm
content: I want to make a FM antenna for my home radio.I would like to use the materials I have on hand.https://www.dropbox.com/s/jado8izsvmhro00/FM_Antenna_Materials.jpg?dl=0I also have wood.Thanks.

author: Audioguru
author_rank: Super Contributor
timestamp: May 27, 2019, 01:52:33 pm
content: You can make a simple antenna or a good one.My high quality home stereo and car radio use a piece of wire or a single whip antenna and they pickup the 25 FM stations in my city and many more stations in cities all around me.My cheap clock radio has its AC cord as its FM antenna and it also picks up the 25 FM stations in my city but none of the others.1) Is your FM radio high quality or cheap?2) Why do you want an FM antenna? What do you use now that does not work?3) Are there far away FM stations that you want to receive?3) is there a building or mountain blocking the signal?

author: fixit7
author_rank: Regular Contributor
timestamp: May 27, 2019, 02:17:13 pm
content: Quote from: Audioguru on May 27, 2019, 01:52:33 pmMy radio is a Denon AVR-1801. Should be high quality.It has no antenna. It has a coaxial connection for a FM antenna.My current antenna is show in my pick.It consists of a UHF/VHF matching transformer with 2 6 foot lengths of spearker wire connected to the spades.It picks up radio stations some of the time.I live in a second story apartment. No mountains near by.Andy

author: Muttley Snickers
author_rank: Unknown
timestamp: May 27, 2019, 02:27:34 pm
content: Is there an existing television antenna connection or socket in the apartment ?.

author: pwlps
author_rank: Frequent Contributor
timestamp: May 27, 2019, 02:30:58 pm
content: Quote from: fixit7 on May 27, 2019, 01:35:18 pmWooden antennas are cute.This one was made by my daughter as a school project.

author: fixit7
author_rank: Regular Contributor
timestamp: May 27, 2019, 02:33:18 pm
content: Quote from: Muttley Snickers on May 27, 2019, 02:27:34 pmThere is what looks to be a coaxial jack.20 feet away from radio.

author: Muttley Snickers
author_rank: Unknown
timestamp: May 27, 2019, 02:46:03 pm
content: Quote from: fixit7 on May 27, 2019, 02:33:18 pmI would try using that connection first and if possible re-locate the receiver or run a cable underneath the carpet. If the socket is working and connected to an external antenna it might also be suitable for FM reception.

author: fixit7
author_rank: Regular Contributor
timestamp: May 27, 2019, 02:51:19 pm
content: That would involve extra expense.I want to make an antenna myself.I once made a tv antenna using my materials, so this should be a doable project and a learning experience.

author: fixit7
author_rank: Regular Contributor
timestamp: May 27, 2019, 02:52:39 pm
content: Quote from: pwlps on May 27, 2019, 02:30:58 pmThanks.I have everything I need.

author: MarkF
author_rank: Super Contributor
timestamp: May 27, 2019, 03:08:08 pm
content: I gathered this info that may help.

author: fixit7
author_rank: Regular Contributor
timestamp: May 27, 2019, 07:37:20 pm
content: 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

author: richnormand
author_rank: Unknown
timestamp: May 27, 2019, 08:05:19 pm
content: 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.htmlIt may not be the best but it is easy to conceal in an unobtrusive spot (if you want, I have not).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.

author: ocw
author_rank: Regular Contributor
timestamp: May 27, 2019, 08:29:01 pm
content: 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.

author: fixit7
author_rank: Regular Contributor
timestamp: May 27, 2019, 08:34:04 pm
content: Quote from: richnormand on May 27, 2019, 08:05:19 pmMy radio has a 75 ohm coaxial connection and one for a loop antenna for am.

author: richnormand
author_rank: Unknown
timestamp: May 27, 2019, 08:43:57 pm
content: Then a simple balun will work for you.https://skyviewelectronics.com/tv-antenna/300-75-ohm-transformer-video-balun-0They 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?

author: MarkF
author_rank: Super Contributor
timestamp: May 27, 2019, 09:19:44 pm
content: Your whiskers and spacing may be too short.The previous design was for HD Over-the-Air TV. I think the FM band is a little lower.And his last picture looks like he has a 300 to 75 ohm balun.HDTV design source ishttps://m4antenna.eastmasonvilleweather.com/index.htmlThe FM band is just below analog VHF TV channel 7.

author: fixit7
author_rank: Regular Contributor
timestamp: May 27, 2019, 09:21:22 pm
content: Is there anyway to test my balun?

author: ocw
author_rank: Regular Contributor
timestamp: May 27, 2019, 09:34:05 pm
content: The main problem is using a UHF TV antenna to receive the FM broadcast frequencies. The elements should be close to 5 feet (1.5M) from tip to tip. The vertical spacing should be about the same distance for a short vertically spaced antenna, over twice the width for normal full wavelength spacing.

author: MarkF
author_rank: Super Contributor
timestamp: May 27, 2019, 09:34:33 pm
content: Quote from: fixit7 on May 27, 2019, 09:21:22 pmI doubt that it is bad.I believe they are just a transformer inside.For a sanity check, you can check continuity between the input terminals and between the output terminals.

author: richnormand
author_rank: Unknown
timestamp: May 27, 2019, 09:47:45 pm
content: 1)As I said in my reply #11 the antenna length is about 150cm (152.4cm is 5 feet). Close for FM 88 to 108MHz.2)Baluns rarely go bad. In particular if used inside. Simple DC conductivity test will tell. You have an ohm meter? If not a battery with an LED will do.

author: fixit7
author_rank: Regular Contributor
timestamp: May 27, 2019, 10:13:43 pm
content: Quote from: MarkF on May 27, 2019, 09:34:33 pm1.41.41.41.6

author: james_s
author_rank: Super Contributor
timestamp: May 27, 2019, 10:19:17 pm
content: There are all kinds of antenna designs out there, usually I find that a simple piece of wire works adequately for FM broadcast. If there is a specific station that you wish to receive then you can optimize for the frequency it is transmitting or a directional antenna can improve reception from a specific area. It's all a matter of compromise, you can have an antenna that does a fair job of a lot of things or you can have one that does a good job at one specific thing or set of circumstances.

author: fixit7
author_rank: Regular Contributor
timestamp: June 02, 2019, 01:18:31 pm
content: I am using this. It picks up many FM stations in stereo.https://www.dropbox.com/s/6kuf4bgb9f32p8q/dipole_Antenna.jpg?dl=0But there is one station (90.5 MHz) that I can only hear in mono.Would it help if I extended the length of the two pieces of the 2 wires at the top of the Y?https://www.dropbox.com/s/ueual4kkympw5nm/Fm_Radio_Antenna.jpg?dl=0Thanks.

author: james_s
author_rank: Super Contributor
timestamp: June 03, 2019, 12:52:00 am
content: That's just a basic dipole, you could measure it and see whether you'd want to extend or trim it shorter in order to optimize it for the wavelength you want. You'll likely find that location and orientation has a greater effect than length.

author: fixit7
author_rank: Regular Contributor
timestamp: June 03, 2019, 02:40:32 am
content: thanks.I will try mounting it at different angles.

author: radiolistener
author_rank: Super Contributor
timestamp: June 03, 2019, 07:04:10 am
content: get away your antenna from walls and place it outside home, as far as possible. And as high as possible, it should be at least 1.7 meters away from the ground and from any objects.