I hope someone can help me.

I have a Denon home stereo and I want to add an antenna for FM stations.

The back has an coaxial input for FM.

I made this.

https://www.dropbox.com/s/i1hhzwj7kg...tenna.jpg?dl=0

But the reception is not great. It picks up some FM stations, but most of the others only come in in AM.

Rotating antenna does not help much.

Any thing else to try?

Andy

Take a look at

https://www.electronics-notes.com/ar...le-antenna.php

On Monday, May 27, 2019 at 6:29:43 PM UTC-5, wrote:
Take a look at

https://www.electronics-notes.com/ar...le-antenna.php

This is where the link takes me.

Redirecting you to https://www.electronics-notes.com/ar...le-antenna.php

On Monday, May 27, 2019 at 3:34:01 PM UTC-7, wrote:

Any thing else to try?
The traditional antenna is a "folded dipole" made from "300-ohm twin-lead".

http://home.earthlink.net/~dsc560/an...Reception.html

If you do not have the twin-lead, you can probably buy one ready-made for less than $10 from your favorite electronics surplus store, or you can spend about $1 to buy the twin lead to build your own.

On Mon, 27 May 2019 18:29:55 -0700, scientist77017 wrote:

+AD4 On Monday, May 27, 2019 at 6:29:43 PM UTC-5, richp...+AEA-gmail.com wrote:
+AD4APg Take a look at
+AD4APg
+AD4APg https://www.electronics-notes.com/ar...le-antenna.php
+AD4
+AD4 This is where the link takes me.
+AD4
+AD4 Redirecting you to https://www.electronics-notes.com/ar...le-antenna.php

OK, I'm not getting a redirect. But the page that shows gives pretty good information on building a basic FM dipole.

Some further points:

If your radio has a coaxial connector for the FM antenna, a simple dipole will match the radio better than a folded dipole. A folded dipole will work OK but a simple dipole will transfer a little more signal.

The length of the dipole isn't supercritical. A few inches one way or the other doesn't make much difference.

The dipole will work best if it's kept in a straight line.

If you're in the US, most FM broadcasters are transmitting a circular polarized signal now. This means that the receiving antenna can be horizontally or vertically oriented or anywhere in between and still work.

If you want to try something quick and dirty, put the bare end of a thin wire about 5 feet long into the center terminal of the radio's coax antenna connector. This is hardly ideal but it's easy and might work well enough.

On Tuesday, May 28, 2019 at 3:25:47 AM UTC-5, Frank wrote:
On Mon, 27 May 2019 18:29:55 -0700, scientist77017 wrote:

On Monday, May 27, 2019 at 6:29:43 PM UTC-5, wrote:
Take a look at

https://www.electronics-notes.com/ar...le-antenna.php

This is where the link takes me.

Redirecting you to https://www.electronics-notes.com/ar...le-antenna.php

OK, I'm not getting a redirect. But the page that shows gives pretty good information on building a basic FM dipole.

Some further points:

If your radio has a coaxial connector for the FM antenna, a simple dipole will match the radio better than a folded dipole. A folded dipole will work OK but a simple dipole will transfer a little more signal.

The length of the dipole isn't supercritical. A few inches one way or the other doesn't make much difference.

The dipole will work best if it's kept in a straight line.

If you're in the US, most FM broadcasters are transmitting a circular polarized signal now. This means that the receiving antenna can be horizontally or vertically oriented or anywhere in between and still work.

If you want to try something quick and dirty, put the bare end of a thin wire about 5 feet long into the center terminal of the radio's coax antenna connector. This is hardly ideal but it's easy and might work well enough.

Youtube Shutdown Of Last Short Wave Transmitters At Radio Australia by vk3ase, published on Feb 5, 2017

On Tuesday, May 28, 2019 at 7:10:12 PM UTC-5, James Ryan wrote:
On Tuesday, May 28, 2019 at 3:25:47 AM UTC-5, Frank wrote:
On Mon, 27 May 2019 18:29:55 -0700, scientist77017 wrote:

On Monday, May 27, 2019 at 6:29:43 PM UTC-5, wrote:
Take a look at

https://www.electronics-notes.com/ar...le-antenna.php

This is where the link takes me.

Redirecting you to https://www.electronics-notes.com/ar...le-antenna.php

OK, I'm not getting a redirect. But the page that shows gives pretty good information on building a basic FM dipole.

Some further points:

If your radio has a coaxial connector for the FM antenna, a simple dipole will match the radio better than a folded dipole. A folded dipole will work OK but a simple dipole will transfer a little more signal.

The length of the dipole isn't supercritical. A few inches one way or the other doesn't make much difference.

The dipole will work best if it's kept in a straight line.

If you're in the US, most FM broadcasters are transmitting a circular polarized signal now. This means that the receiving antenna can be horizontally or vertically oriented or anywhere in between and still work.

If you want to try something quick and dirty, put the bare end of a thin wire about 5 feet long into the center terminal of the radio's coax antenna connector. This is hardly ideal but it's easy and might work well enough.

Youtube Shutdown Of Last Short Wave Transmitters At Radio Australia by vk3ase, published on Feb 5, 2017

A couple more,,, Youtube BC 375 world war ll transmitter used in B17 flying fortress by LifeIsTooShortForQRP published on May 14,2017 annnd, Youtube Woofferton shortwave transmitting station by Bclnews published on Dec 22,2013

In article , Frank writes:
If your radio has a coaxial connector for the FM antenna, a simple dipole
will match the radio better than a folded dipole. A folded dipole will
work OK but a simple dipole will transfer a little more signal.

Or use a 75:300 ohm balun. I know, balun losses. But then a dipole
of the sort you recommend has issues, too: the balanced to unbalanced
transition leads to antenna currents in the feed line. Assuming you
have one.

Also: a folded dipole is a broader band device than a simple dipole.

Another simple one is a loop. I believe the length is 1055/f,
making it about 10.5' long. It's lower impedance than a folded
dipole and may actually be a good match to a 75 ohm input.

Shape isn't too important - a circle or a square is common.
A square antenna is commonly called a quad.

If you want to try something quick and dirty, put the bare end of
a thin wire about 5 feet long into the center terminal of the radio's
coax antenna connector. This is hardly ideal but it's easy and might
work well enough.

Well, the hams use 468/f for a dipole, 234/f for a 1/4 wave. So for a center
frequency of 100Mhz, that would translate to 2.34' . Assuming you have a
ground plane. Hmmm. Never heard of anyone building a ground plane antenna
for FM radio. Be the first on your block to try it!

George

On Wed, 26 Jun 2019 03:02:38 -0400, George Cornelius wrote:

+AD4 In article +ADw-qcira8+ACQ-v05+ACQ-1+AEA-dont-email.me+AD4, Frank +ADw-analogdial+AEA-mail.com+AD4 writes:
+AD4APg If your radio has a coaxial connector for the FM antenna, a simple dipole
+AD4APg will match the radio better than a folded dipole. A folded dipole will
+AD4APg work OK but a simple dipole will transfer a little more signal.
+AD4
+AD4 Or use a 75:300 ohm balun. I know, balun losses. But then a dipole
+AD4 of the sort you recommend has issues, too: the balanced to unbalanced
+AD4 transition leads to antenna currents in the feed line. Assuming you
+AD4 have one.

Not sure the OP cares anymore but it's always nice to change the pace from the usual +ACI-TRUMP+ACI-talk.

For receiving, antenna currents on the feedline won't do much beside alter the pattern a bit. I suppose the feed will pick up more interference but I expect this radio and antenna will be in the same room, anyway.

+AD4
+AD4 Also: a folded dipole is a broader band device than a simple dipole.

With the same amount of wire, I suspect that a fan dipole (like this -- +AD4APA ) would have a broader spread yet than a folded dipole. For each leg of the dipole just cut one wire a little long and another a little short. Put about a 10 or 15 degree angle between the long and short wires. But bandwidth of a simple dipole should be OK.
+AD4
+AD4 Another simple one is a loop. I believe the length is 1055/f,
+AD4 making it about 10.5' long. It's lower impedance than a folded
+AD4 dipole and may actually be a good match to a 75 ohm input.

That's a good one. A loop like that could be placed on a door which would allow the pattern to be aimed.
+AD4
+AD4 Shape isn't too important - a circle or a square is common.
+AD4 A square antenna is commonly called a quad.
+AD4
+AD4APg If you want to try something quick and dirty, put the bare end of
+AD4APg a thin wire about 5 feet long into the center terminal of the radio's
+AD4APg coax antenna connector. This is hardly ideal but it's easy and might
+AD4APg work well enough.
+AD4
+AD4 Well, the hams use 468/f for a dipole, 234/f for a 1/4 wave. So for a center
+AD4 frequency of 100Mhz, that would translate to 2.34' .

Well, ya got me there. 5 feet would be more like a end fed half wave dipole which would be a severe mismatch to a low Z input. A couple more feet and it would be a 3/4 wave end fed antenna which would be a better match and give some offset lobes which may or may not be helpful.

If I REALLY want a resonant antenna I check them with a grid dip meter. The formulas usually are off a bit in the real world but, for receiving, they're plenty close. If the receiver has a S meter that meter can be used for tuning the antenna. But a few inches one way or the other won't make much difference.

+AD4 Assuming you have a
+AD4 ground plane. Hmmm. Never heard of anyone building a ground plane antenna
+AD4 for FM radio. Be the first on your block to try it+ACE
+AD4
+AD4 George

I find the top of the refrigerator makes an easy, kinda sorta ground plane for a FM portable.

In article , Frank writes:
Not sure the OP cares anymore but it's always nice to
change the pace from the usual TRUMP talk.

Amen.

For receiving, antenna currents on the feedline won't do much beside alter
the pattern a bit. I suppose the feed will pick up more interference but
I expect this radio and antenna will be in the same room, anyway.

I used to think something like that. But losses in transmission,
scaled down, are losses in receiving as well. Just that you have
AGC - and therefore rather impressive changes in RF/IF gain - at your
disposal to swamp out so many of the receiving losses. Until you get
down to the noise floor, at which point antenna gain becomes important
in the same way it is in transmitting.

Well, the hams use 468/f for a dipole, 234/f for a 1/4 wave. So for a center
frequency of 100Mhz, that would translate to 2.34' .

Well, ya got me there. 5 feet would be more like a end fed half
wave dipole which would be a severe mismatch to a low Z input.

Don't give up too easily. After I posted I realized a 100Mhz 5/8
wave would be only slightly longer than what you suggested. It has
gain relative to a dipole, I believe, but requires a ground plane
for best results. For reasons mentioned below - a 5/8 wave in
the middle of the band is close to a 1/2 wave at the low end of
the band - that might not be ideal for the OP, though.

A couple more feet and it would be a 3/4 wave end fed antenna
which would be a better match and give some offset lobes which[...]

If I REALLY want a resonant antenna I check them with a grid
dip meter.

Mine died quite some time ago. Guess I need to start
replacing capacitors. Then there's that Heathkit Tunnel
Dipper I found at a swap meet. Might even work. Now if
I knew what box I put it was in when I moved...

But we are most likely not going to want a resonant antenna.
Middle of the road, broadband if possible, should be the
target. The problem, as you mention, for an end fed
1/2 wave as with a full wave dipole - is that it just
doesn't match up very well to ANY low inpedance input.

The formulas usually are off a bit in the real world but,
for receiving, they're plenty close.

Just speed of light divided by twice the frequency (four
times for 1/4 wave), with a minor adjustment for velocity
factor of a typical HF antenna.

A quarter wave without the adjustment would be 246/f .

I find the top of the refrigerator makes an easy,
kinda sorta ground plane for a FM portable.

Actually should be quite good.

The top of my old Harmon Kardon receiver is probably
reasonable, though at ~18" wide it is not nearly as
good as a typical refrigerator.

I vote for a 2' x 3' quad, 18-22 AWG, glued to the back
of a slightly larger, preferably framed, movie poster.

George