Our local cable company, Comcast, doesn't carry FM radio signals; therefore,
I'm trying to improve my FM reception on my home receiver. I've had separate
VHF and UHF antennas up for HDTV several years. They work wonders for HD and
even analog TV, but the FM element on the VHF yagi surprisingly doesn't pick
up much. Part of my problem is that I'm on an east facing hillside in the
foothills directly north of one major metro market area and directly west of
another. Despite that, I don't understand why I can get decent TV reception
but no FM.

After limited success with a homebrew folded dipole, I picked up a high gain
three element FM yagi. No matter where I seem to point it, I'm not getting
any more signal strength than with the dipole on the back of the receiver.
You'd think that aiming it east, southeast, or south towards all those
transmitters would pull in something, but gain is very weak. However, if I
point it northwest, at about 45 degrees up the hill behind me, I can
actually pull in a few decent stations. Aiming the antenna in the opposite
direction of the stations just seems contrary to logic. I understand that
ground waves travel parallel to the earth, but could the signals be bouncing
off the hillside too, acting like a huge reflector?

The thing that really gets me is that I can get excellent reception on all
stations in my car sitting in the driveway, and driving around. Therefore,
I'm thinking of dumping the yagi and trying to find or build a vertically
polarized omni antenna. My car antenna does happen to be mounted at about 45
degrees. Any ideas on what might be going on, and how I might improve my
reception? Any antenna designs and dimensions would be helpful. I guess
worst case scenario is I can go down to the auto parts store, by a car
antenna, and put it on my roof.

Please help. Many thanks!

-Bob

On Thu, 9 Jun 2005 08:10:41 -0700, "butlercellars"
wrote:

You'd think that aiming it east, southeast, or south towards all those
transmitters would pull in something, but gain is very weak.

Hi Bob,

Metropolitan FM stations are not always located downtown.

However, if I
point it northwest, at about 45 degrees up the hill behind me, I can
actually pull in a few decent stations.

This may be evidence of where the transmitters are.

Aiming the antenna in the opposite
direction of the stations just seems contrary to logic. I understand that
ground waves travel parallel to the earth, but could the signals be bouncing
off the hillside too, acting like a huge reflector?

Yes, very much so at this frequency. As in gold prospecting, the
signal is where you find it.

The thing that really gets me is that I can get excellent reception on all
stations in my car sitting in the driveway, and driving around. Therefore,
I'm thinking of dumping the yagi and trying to find or build a vertically
polarized omni antenna.

This is more telling. It suggests that perhaps you haven't properly
connected either the antenna to the feeline, or the feedline to the
receiver, or yes the antenna is still not pointed in the right
direction - or you have a bum receiver. What about an FM portable
with a whip antenna? What about that FM portable with your antenna
feedline attached? If the whip works better, look at the feedline and
up.

73's
Richard Clark, KB7QHC

Good suggestions, but there are no problems with the receiver, feedline, or
antenna. And I know exactly where the xmitter towers are, including degrees
orientation. Topo maps indicate I'm in a pocket; however, I thought FM
signals would be more forgiving, not VHF and UHF TV as is the case.

FM portable w/ built-in whip antenna, dipole, or feedline/yagi reception is
still marginal. My boat FM radio w/short rubber ducky performs as well as
the car, but I don't want to sit in them to listen to the radio. As I
stated in my original post, my VHF antenna has 1/2 wave horizontal FM
elements too. The antenna works great for TV, but not FM. There's just
something about my terrain where 1/2 wave horizontal FM elements are
ineffective. Therefore, I'd like to try a good vertical (semi-vertical)
omni.

-Bob



"Richard Clark" wrote in message
...
On Thu, 9 Jun 2005 08:10:41 -0700, "butlercellars"
wrote:

You'd think that aiming it east, southeast, or south towards all those
transmitters would pull in something, but gain is very weak.

Hi Bob,

Metropolitan FM stations are not always located downtown.

However, if I
point it northwest, at about 45 degrees up the hill behind me, I can
actually pull in a few decent stations.

This may be evidence of where the transmitters are.

Aiming the antenna in the opposite
direction of the stations just seems contrary to logic. I understand that
ground waves travel parallel to the earth, but could the signals be
bouncing
off the hillside too, acting like a huge reflector?

Yes, very much so at this frequency. As in gold prospecting, the
signal is where you find it.

The thing that really gets me is that I can get excellent reception on all
stations in my car sitting in the driveway, and driving around. Therefore,
I'm thinking of dumping the yagi and trying to find or build a vertically
polarized omni antenna.

This is more telling. It suggests that perhaps you haven't properly
connected either the antenna to the feeline, or the feedline to the
receiver, or yes the antenna is still not pointed in the right
direction - or you have a bum receiver. What about an FM portable
with a whip antenna? What about that FM portable with your antenna
feedline attached? If the whip works better, look at the feedline and
up.

73's
Richard Clark, KB7QHC

On Thu, 9 Jun 2005 10:33:16 -0700, "butlercellars"
wrote:

FM portable w/ built-in whip antenna, dipole, or feedline/yagi reception is
still marginal. My boat FM radio w/short rubber ducky performs as well as
the car, but I don't want to sit in them to listen to the radio.

Hi Bob,

This would suggest there is enough signal, or those working receivers
are exceptional. Go to Radio Shack and invest in a signal booster.
Get an over the air amplifier rather than a line amplifier. If
there's a separate line for the FM, from the antenna, get a mast
mounted, line powered amplifier.

It is odd that all the FM stations would be solely vertical
polarization. This would explain the horizontal antenna deafness.
There is also the old real-estate saw of "location, location,
location" and as you offer, yours sucks (maybe). Sitting there in the
Napa valley, are you trying to hit Frisco?

73's
Richard Clark, KB7QHC

On Thu, 09 Jun 2005 10:50:11 -0700, Richard Clark
wrote:

Get an over the air amplifier rather than a line amplifier. If
there's a separate line for the FM, from the antenna, get a mast
mounted, line powered amplifier.

Hi Bob,

I noticed I used the word "line" in two senses here that may confuse.
The first actually means a line distribution amplifier. This is
usually used to augment a homes cable load of too many TV sets. The
other sense is a transmission line powered amplifier mounted on the
mast just beneath the antenna. Power into the transmission line and
up to the amplifier is applied through a special unit down near the
receiver which handles keeping the DC separate from the RF.

73's
Richard Clark, KB7QHC

Richard Clark wrote:
On Thu, 09 Jun 2005 10:50:11 -0700, Richard Clark
wrote:

Get an over the air amplifier rather than a line amplifier. If
there's a separate line for the FM, from the antenna, get a mast
mounted, line powered amplifier.

Hi Bob,

I noticed I used the word "line" in two senses here that may confuse.
The first actually means a line distribution amplifier. This is
usually used to augment a homes cable load of too many TV sets. The
other sense is a transmission line powered amplifier mounted on the
mast just beneath the antenna. Power into the transmission line and
up to the amplifier is applied through a special unit down near the
receiver which handles keeping the DC separate from the RF.

73's
Richard Clark, KB7QHC



Try orienting your Yagi with the elements vertical like the car antenna
is.

Also try another receiver.

If you car radio picks up the stations in front of your house, you
should be able to get them with your receiver. If not, your
receiver, ant cable or ant are broke.



Mark

No problems with the gear. Someone in sci.engr.television.broadcast nailed
it on the first try. There's a 99FM xmitter a couple miles to the SE of
me, lower in elevation, right in the path of all the
other stations - & right smack in the middle of the FM band. Pointing the
yagi in the exact opposite direction yields the best results for all other
stations.

I'm still looking for some vertical omni antenna designs. Sorry for any
duplicate posts, my hotmail account isn't very reliable.

-Bob
"Mark" wrote in message
oups.com...


Richard Clark wrote:
On Thu, 09 Jun 2005 10:50:11 -0700, Richard Clark
wrote:

Get an over the air amplifier rather than a line amplifier. If
there's a separate line for the FM, from the antenna, get a mast
mounted, line powered amplifier.

Hi Bob,

I noticed I used the word "line" in two senses here that may confuse.
The first actually means a line distribution amplifier. This is
usually used to augment a homes cable load of too many TV sets. The
other sense is a transmission line powered amplifier mounted on the
mast just beneath the antenna. Power into the transmission line and
up to the amplifier is applied through a special unit down near the
receiver which handles keeping the DC separate from the RF.

73's
Richard Clark, KB7QHC



Try orienting your Yagi with the elements vertical like the car antenna
is.

Also try another receiver.

If you car radio picks up the stations in front of your house, you
should be able to get them with your receiver. If not, your
receiver, ant cable or ant are broke.



Mark

wrote
There's a 99FM xmitter a couple miles to the SE of me, lower in elevation,
right in the path of all the
other stations - & right smack in the middle of the FM band. Pointing the
yagi in the exact opposite direction yields the best results for all other
stations.

I'm still looking for some vertical omni antenna designs. Sorry for any
duplicate posts, my hotmail account isn't very reliable.
____________

Using an omni v-pol antenna for the receiver with the problem won't help
much if the 99FM xmit antenna radiates v-pol as well as h-pol -- which is
typical for FM stations.

Really fixing the problem will require changing your receiver to one with
better selectivity. It is being de-sensitized by that local FM station.

An option would be to install a notch filter tuned for the local FM at the
input to the problem receiver. It will attenuate that local signal (and
others close to it in frequency, to some extent). A "5KFM" type notch
filter from Microwave Filter Company may do the job, for about $25 as I
recall. Here is a link: http://www.microwavefilter.com/

RF

"butlercellars" wrote in message
...
.......................................
As I stated in my original post, my VHF antenna has 1/2 wave horizontal
FM elements too. The antenna works great for TV, but not FM. There's
just something about my terrain where 1/2 wave horizontal FM elements are
ineffective. Therefore, I'd like to try a good vertical (semi-vertical)
omni.

-Bob

Are you sure about that? Generally, a VHF TV antenna with two sets of
elements has one set for channels 2 - 6 and another for 7 - 13. FM elements
would be about 4-1/2 feet tip to tip.


Tam/WB2TT

Actually, some TV antennas reject the FM band so that strong FM signals
don't overload the TV receiver front end.

73,
Bob AD3K

"Tam/WB2TT" wrote in message
...

"butlercellars" wrote in message
...
......................................
As I stated in my original post, my VHF antenna has 1/2 wave horizontal
FM elements too. The antenna works great for TV, but not FM. There's
just something about my terrain where 1/2 wave horizontal FM elements
are
ineffective. Therefore, I'd like to try a good vertical (semi-vertical)
omni.

-Bob

Are you sure about that? Generally, a VHF TV antenna with two sets of
elements has one set for channels 2 - 6 and another for 7 - 13. FM
elements
would be about 4-1/2 feet tip to tip.


Tam/WB2TT