FM Antenna Over Ethernet
Intro: FM Antenna Over Ethernet
Problem: I ran cat6 and coax throughout my house. But for some reason the notion of installing an extra coax or simple antenna wire never occurred to me. Now I have no way of using my nice FM tuner unless I hang an ugly dipole from the wall.
Solution: I have an extra Ethernet connection available near my audio equipment. I simply used the cat 6 run as an extension - allowing me to hang a dipole antenna in my data closet out of site.
Solution: I have an extra Ethernet connection available near my audio equipment. I simply used the cat 6 run as an extension - allowing me to hang a dipole antenna in my data closet out of site.
STEP 1: Tuner Side
(pictures could be provided if there is adequate interest)
I made the connection at the tuner by putting an rj45 connection on one end of the cable. Then at the other end I simply unjacketed about 1.5 inches of wire. then stripped off one inch of insulation from all 8 wires. Then I twisted 2 pairs into one bundle and the other 2 pairs in the other. Then connecting one of each of the wire bundles to the two FM antenna connectors on the tuner. The pairs you use doesn't matter just as long as you stay consistent. I used the Blue pair and green pair together and the orange and brown pair together.
I made the connection at the tuner by putting an rj45 connection on one end of the cable. Then at the other end I simply unjacketed about 1.5 inches of wire. then stripped off one inch of insulation from all 8 wires. Then I twisted 2 pairs into one bundle and the other 2 pairs in the other. Then connecting one of each of the wire bundles to the two FM antenna connectors on the tuner. The pairs you use doesn't matter just as long as you stay consistent. I used the Blue pair and green pair together and the orange and brown pair together.
STEP 2: Antenna Side
At the other end in my data closet, I basically repeated the process.
1) Putting a rj45 connector on one end of my cable (using the same wiring order as the connector at the tuner end)
2) then I measured to see how much extra wire is needed to get the antenna dipole up and way from the wiring hub. ***
3) then I added another 50cm of wire
4) then I stripped a full 50cm of jacket off.
5) then stretched approximately 49cm of the Blue/Green pair along one half of a 100+cm dowel , and then stretched the other 49 cms of orange/brown pair along the other half. Then i firmly taped them to the dowel to ensure they don't sag (apparently keeping both legs the same length is essential).
*** in case you dont know better - DONT attach your antenna to your router/hub - you want only dead wire - no network traffic anywhere near your antenna.
1) Putting a rj45 connector on one end of my cable (using the same wiring order as the connector at the tuner end)
2) then I measured to see how much extra wire is needed to get the antenna dipole up and way from the wiring hub. ***
3) then I added another 50cm of wire
4) then I stripped a full 50cm of jacket off.
5) then stretched approximately 49cm of the Blue/Green pair along one half of a 100+cm dowel , and then stretched the other 49 cms of orange/brown pair along the other half. Then i firmly taped them to the dowel to ensure they don't sag (apparently keeping both legs the same length is essential).
*** in case you dont know better - DONT attach your antenna to your router/hub - you want only dead wire - no network traffic anywhere near your antenna.
STEP 3: Where It Might Be Improved
I suspect there is a person out there with some RF knowledge that could fill me in on some balancing issues - but hey it definitely works!
1) I suspect I didnt need all 4 pairs to make the antenna. And if a person didn't have a full ethernet connection avaialble they could just pull a couple pairs off an existing ethernet or availalble phone line to do the same (being very cautious abour any current in the phone or network connections)
2) Sure I could have bought a digital tuner and used that on the ethernet - but that would have been more expensive.
3) I suspect the same could be done for AM tuning - simply eliminating the dipole and using the ethernet as a long wire antenna.
1) I suspect I didnt need all 4 pairs to make the antenna. And if a person didn't have a full ethernet connection avaialble they could just pull a couple pairs off an existing ethernet or availalble phone line to do the same (being very cautious abour any current in the phone or network connections)
2) Sure I could have bought a digital tuner and used that on the ethernet - but that would have been more expensive.
3) I suspect the same could be done for AM tuning - simply eliminating the dipole and using the ethernet as a long wire antenna.
28 Comments
DanM2 9 years ago
for wifi, use a pi microcomputer and a wifi dongle, connected with ethernet to your router. or use LMR-1200 cable. using cat 5/6 with wifi will radiate the signal in the transmission line, and you will get very little signal out.
cat6 has 100ohms between twisted pairs so your impedance when using all 8 is 25homs. best stick to 4 not all 8 and balun between the antenna, and cat6
brianlee 10 years ago
I wonder if this would work for WiFi. I really would like to extend my WiFi coverage around the house and if only I can utilize existing CAT5! The telephone wire antenna hack also sounds intriguing!
Cameron657 13 years ago
techwiz 16 years ago
cowen 14 years ago
jaydenthorup 14 years ago
Drofnats 15 years ago
static 14 years ago
static 14 years ago
lukethedog 14 years ago
I also once knew but have long forgotten the length that a dipole needs to be to receive 88mhz to 108mhz (US FM broadcasting).
I found loads of information at this site in my search
http://www.educypedia.be/electronics/antennadipole.htm
static 14 years ago
ThinkBeforeYouSpeak 14 years ago
biospot 14 years ago
However.. I would point out one simple change that may make an improvement on your system.. or may not. The test would be very interesting to me.
The idea is that each twisted pair rejects the pickup of radio interference if each wire of a twisted pair is connected to opposite sides. The way you have wired it, each twisted pair is actually a single long antenna wire, and picks up radio waves. So, the wire traveling from your radio to the computer closet itself is a very long antenna.
IF you changed the wireing by untwisting the pairs at the ends, and wired them as 4 wires "solid" and 4 wired "striped", then each twisted pair would reject noise from Flourescents, computers and other EMI generators.
The big question in my mind is does your method gather more radio waves, or more interference from other devices....
In any event, I will try it both ways myself one day.
I would also wonder if 1 pair of the 4 pairs could be dedicated to AM connections. I hate to have something unusable. In that case, I am certain it would be best for 1 twisted pair to be used on both sides of the connection. AM will pickup huge amounts of EMI, unless you use a twisted pair. I even have a wired loop antenna I got with an AM radio that uses twisted pair as the antenna lead in wires, so I am certain it will work. If you try it, I would be interested to see the results in your "improved" PDF
Thanks for an intersting Instructable
bleachworthy 16 years ago
noahw 16 years ago
bleachworthy 16 years ago
Derin 15 years ago
ReCreate 14 years ago
klingoncowboy4 14 years ago
LMAO could be interesting... but I don't want to try it with any of my current networking or radio receiver equipment
n7tcf 15 years ago