DIY FM antenna, can it be better than radioshack junk? - diyAudio
Go Back   Home > Forums > General Interest > Everything Else

Everything Else Anything related to audio / video / electronics etc) BUT remember- we have many new forums where your thread may now fit! .... Parts, Equipment & Tools, Construction Tips, Software Tools......

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 8th June 2005, 07:06 PM   #1
homer09 is offline homer09  Canada
diyAudio Member
 
homer09's Avatar
 
Join Date: Jan 2004
Location: Montreal
Arrow DIY FM antenna, can it be better than radioshack junk?

Im looking for a good DIY FM antenna for my Yamaha t-1 tuner. Right now im using a dipole and it pulls strong signals very well. But, i want to catch 99.9 here in montreal, which is a notoriously difficult one to pull.

Right now, i could catch it in mono/narrow slighlty off-tuning it intentionally. If i hold my dipole vertically, i get a flickering stereo light. So this is fringe reception, i need a little boost to get some nice stereo here.

What are you guys using for indoor FM antennas? A DIY solution interests me. here is what i absolutely need:

- better gain than a standard dipole
- the smaller the better, dont want to have to move furniture for this
- something that doesnt need constant adjustment for each station

shoot away
__________________
Most people wouldn't know good music if it came up and bit them in the ***. - Frank Zappa
  Reply With Quote
Old 8th June 2005, 08:56 PM   #2
dnsey is offline dnsey  United Kingdom
diyAudio Member
 
Join Date: Mar 2004
Location: Shropshire, England
It's perfectly possible and not difficult or expensive to build your own antennas - a member of the amateur radio fraternity would probably be happy to help you with it - but I think you'll have to compromise in order to balance your requirements.
To achieve more gain, your antenna must be more directional. In the case of a Yagi array (the usual type for domestic FM), this is achieved by adding directors and reflectors, which increases the overall size of the antenna. The extra directionality will make it necessary to rotate the array to receive different transmitters.
The only option I can think of is a switched pair of dipoles, one of which is dedicated to your DX station, perhaps with a VHF amplifier added.
All sorts of designs have been tried - some of which use materials such as aluminium foil and cardboard, so cost virtually nothing - you can have a lot of fun experimenting once you grasp the theory.
Whatever you settle on, make sure that it's properly impedence matched to your feeder and tuner - a great deal of signal loss can be due to a mismatch here.
Good luck!
  Reply With Quote
Old 8th June 2005, 09:04 PM   #3
homer09 is offline homer09  Canada
diyAudio Member
 
homer09's Avatar
 
Join Date: Jan 2004
Location: Montreal
thanks for the ideas. can you give me more specific leads for me to get started on? my requirements were in order of importance, so i will sacrifice the last one. do you have a recommended antenna recipe?

impedence matching, can you explain further?
__________________
Most people wouldn't know good music if it came up and bit them in the ***. - Frank Zappa
  Reply With Quote
Old 9th June 2005, 03:50 AM   #4
diyAudio Member
 
TwoSpoons's Avatar
 
Join Date: Oct 2004
You'd better sacrifice #2 as well. Small antenna's won't get the performance as their aperture is smaller (=less power pickup).

The best result is going to be had by putting your antenna on the roof, and using low loss co-ax to feed your receiver. I'd assume your receiver input is 75 Ohm? So you need 75 ohm co-ax (RG-59 IIRC). If you use a folded dipole it will have a 300 ohm impedance, so you will want a 4:1 balun to connect to your coax.
  Reply With Quote
Old 9th June 2005, 03:57 AM   #5
homer09 is offline homer09  Canada
diyAudio Member
 
homer09's Avatar
 
Join Date: Jan 2004
Location: Montreal
Quote:
Originally posted by TwoSpoons
You'd better sacrifice #2 as well. Small antenna's won't get the performance as their aperture is smaller (=less power pickup).

The best result is going to be had by putting your antenna on the roof, and using low loss co-ax to feed your receiver. I'd assume your receiver input is 75 Ohm? So you need 75 ohm co-ax (RG-59 IIRC). If you use a folded dipole it will have a 300 ohm impedance, so you will want a 4:1 balun to connect to your coax.

it has to be an indoor solution, i dont have the liberty to pull coax into my room or mount things on the roof.

my tuner has boath 75 ohm and 300 ohm. which is best to use?

still looking for an indoor solution that beats a dipole...
__________________
Most people wouldn't know good music if it came up and bit them in the ***. - Frank Zappa
  Reply With Quote
Old 9th June 2005, 10:21 PM   #6
diyAudio Member
 
TwoSpoons's Avatar
 
Join Date: Oct 2004
A colinear dipole might help. Though it will need loading coils to get the size down.

Basically, though, you're stuffed if you want gain at 99MHz, and you want it inside. Any solution with gain at that frequency is going to be big - simple physics. After all, the wave length you're after is around 3 metres, so even a proper 1/2 wave dipole is going to be 1.5 metres long.
  Reply With Quote
Old 9th June 2005, 10:38 PM   #7
homer09 is offline homer09  Canada
diyAudio Member
 
homer09's Avatar
 
Join Date: Jan 2004
Location: Montreal
Quote:
Originally posted by TwoSpoons
A colinear dipole might help. Though it will need loading coils to get the size down.

Basically, though, you're stuffed if you want gain at 99MHz, and you want it inside. Any solution with gain at that frequency is going to be big - simple physics. After all, the wave length you're after is around 3 metres, so even a proper 1/2 wave dipole is going to be 1.5 metres long.

well if its big but concealable, i dont mind, i just dont want something that doesnt looks like those big roof top antennas in my room. i dont mind something the size of a standard dipole, only mine isnt performing for me.

do you have more info on colinear dipoles and how i would build one?

thanks for the help, appreaciate it
__________________
Most people wouldn't know good music if it came up and bit them in the ***. - Frank Zappa
  Reply With Quote
Old 14th June 2005, 12:14 AM   #8
diyAudio Member
 
TwoSpoons's Avatar
 
Join Date: Oct 2004
Would you mind accurately describing (or photographing!) what you have currently? It would help knowing where you are starting from, in order to get improvements.
  Reply With Quote
Old 14th June 2005, 12:31 AM   #9
mcs is offline mcs  Denmark
diyAudio Member
 
Join Date: Aug 2003
Location: Denmark
Quote:
Originally posted by homer09
well if its big but concealable, i dont mind, i just dont want something that doesnt looks like those big roof top antennas in my room.
A good FM antenna will be big, and most likely look like one of the roof-top antennas...

But it could still be concealable if you make one yourself using thick copper wire instead of aluminium tubes - that way you could make it flat at least.

Best regards,

Mikkel C. Simonsen
__________________
My personal electronics website
Remote control kits website
  Reply With Quote
Old 14th June 2005, 12:50 AM   #10
homer09 is offline homer09  Canada
diyAudio Member
 
homer09's Avatar
 
Join Date: Jan 2004
Location: Montreal
Thanks dnsey,

Here is my current setup: i have this tuner:

Click the image to open in full size.

Click the image to open in full size.

a write up for the t-1 is available here:

http://www.fmtunerinfo.com/yamaha.html

note: this tuner is much better already than a technics tuner i was using previously (techincs st-c03)


i took a pic of the back of the tuner, but it really isnt clear since my camera is very bad. It basically consists of a 75ohm input, a 300 ohm input and an AM antenna input. (the dipole is currently connected in the 300 ohm input)

Also is a picture of a standard dipole antenna you can buy at any electronics store for a few dollars.

my room is located on the second floor, close to a window.
Attached Images
File Type: jpg pict0001.jpg (30.5 KB, 1718 views)
__________________
Most people wouldn't know good music if it came up and bit them in the ***. - Frank Zappa
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
My DIY UcD amp from the junk box acid_k2 Class D 38 3rd September 2012 05:01 PM
What to do with RadioShack 40-1041? Spasticteapot Full Range 0 14th October 2006 08:14 PM
Radioshack special GC Dustin Haug Chip Amps 16 15th February 2004 03:22 PM
Dr.Bose and Radioshack.. Bose(o) Multi-Way 7 1st January 2003 06:43 PM
WTB: Radioshack RS 40-1354A psarin Swap Meet 1 5th April 2002 07:31 PM


New To Site? Need Help?

All times are GMT. The time now is 11:33 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2