FM Aerials


Paul Blundell
 

Over the upcoming Christmas break I am looking at undertaking some portable FM dxing, given the success of the various FSL aerial for the mediumwave band, what would work the best on the FM band? I have found some instructions for various FM dipoles, would a look work this high?

Paul


Phillips
 

You are dipping into the black-magic world of antennas here.


Commercial FM frequencies are line-of-sight and so antenna height is a DX advantage.

There are few high-gain portable FM options other than Yagi antennas.

Yagi antennas are highly reliant on the physical dimensions of the length and spacing of the antenna elements.
These dimensions are commensurate with the frequency of interest and most Yagi's are half a wavelength wide and probably a bit longer depending on a number of antenna parameters - and that's where the black-magic comes in.

While it is possible to use some jiggery-pokery to reduce a Yagi's physical dimensions, the antenna performance invariably suffers.

A Yagi's gain is dependent on many variables but, aside from the length of the elements, the number of elements have a great importance in antenna gain and antenna directionality.  However, as the number of elements rise, the increase in performance diminishes. 

For serious portable use,  I would suggest the best compromise of size and performance is 5 elements - 1 reflector, 1 active, and 3 directors. Such an antenna for the commercial FM band is unlikely to fit in a car and would need to be carried on roof racks.

You can get Yagi designs off the 'net (make sure the design is for your frequencies of interest).

You can use MMana-gal software (free and very good) to design your own or to model designs of interest.

Warning!!  Antenna design is addictive!


From: main@UltralightDX.groups.io <main@UltralightDX.groups.io> on behalf of Paul Blundell <tanger32au@...>
Sent: Thursday, 10 December 2020 3:23 PM
To: main@UltralightDX.groups.io <main@UltralightDX.groups.io>
Subject: [UltralightDX] FM Aerials
 
Over the upcoming Christmas break I am looking at undertaking some portable FM dxing, given the success of the various FSL aerial for the mediumwave band, what would work the best on the FM band? I have found some instructions for various FM dipoles, would a look work this high?

Paul


kevin asato <kc6pob@...>
 


Not too portable but i have used an old log periodic style television antenna (US market) which tuned down to 56MHz and up through UHF. it helps receiving signals up and down the coast from the Los Angeles coastline (San Diego to Ventura). The problem is that the very high mountains around Los Angeles do not allow much more to leak in as FM broadcast is a bit more line of sight. As I live near the coastline, i do experience some interesting ducting effects at times. During those times, a half or 5/8 wave 2 meter vertical antenna works well.
73,
kevin
kc6pob

On Wednesday, December 9, 2020, 09:12:47 PM PST, Paul Blundell <tanger32au@...> wrote:


Over the upcoming Christmas break I am looking at undertaking some portable FM dxing, given the success of the various FSL aerial for the mediumwave band, what would work the best on the FM band? I have found some instructions for various FM dipoles, would a look work this high?

Paul


Paul Blundell
 

Thanks. I have used that software before, I will download it and have a play around.


On Thu., 10 Dec. 2020, 17:55 Phillips, <phillicom@...> wrote:
You are dipping into the black-magic world of antennas here.


Commercial FM frequencies are line-of-sight and so antenna height is a DX advantage.

There are few high-gain portable FM options other than Yagi antennas.

Yagi antennas are highly reliant on the physical dimensions of the length and spacing of the antenna elements.
These dimensions are commensurate with the frequency of interest and most Yagi's are half a wavelength wide and probably a bit longer depending on a number of antenna parameters - and that's where the black-magic comes in.

While it is possible to use some jiggery-pokery to reduce a Yagi's physical dimensions, the antenna performance invariably suffers.

A Yagi's gain is dependent on many variables but, aside from the length of the elements, the number of elements have a great importance in antenna gain and antenna directionality.  However, as the number of elements rise, the increase in performance diminishes. 

For serious portable use,  I would suggest the best compromise of size and performance is 5 elements - 1 reflector, 1 active, and 3 directors. Such an antenna for the commercial FM band is unlikely to fit in a car and would need to be carried on roof racks.

You can get Yagi designs off the 'net (make sure the design is for your frequencies of interest).

You can use MMana-gal software (free and very good) to design your own or to model designs of interest.

Warning!!  Antenna design is addictive!


From: main@UltralightDX.groups.io <main@UltralightDX.groups.io> on behalf of Paul Blundell <tanger32au@...>
Sent: Thursday, 10 December 2020 3:23 PM
To: main@UltralightDX.groups.io <main@UltralightDX.groups.io>
Subject: [UltralightDX] FM Aerials
 
Over the upcoming Christmas break I am looking at undertaking some portable FM dxing, given the success of the various FSL aerial for the mediumwave band, what would work the best on the FM band? I have found some instructions for various FM dipoles, would a look work this high?

Paul


Paul Blundell
 

Thanks for the ideas. I might see what I can find locally.


On Thu., 10 Dec. 2020, 18:03 kevin asato via groups.io, <kc6pob=yahoo.com@groups.io> wrote:

Not too portable but i have used an old log periodic style television antenna (US market) which tuned down to 56MHz and up through UHF. it helps receiving signals up and down the coast from the Los Angeles coastline (San Diego to Ventura). The problem is that the very high mountains around Los Angeles do not allow much more to leak in as FM broadcast is a bit more line of sight. As I live near the coastline, i do experience some interesting ducting effects at times. During those times, a half or 5/8 wave 2 meter vertical antenna works well.
73,
kevin
kc6pob

On Wednesday, December 9, 2020, 09:12:47 PM PST, Paul Blundell <tanger32au@...> wrote:


Over the upcoming Christmas break I am looking at undertaking some portable FM dxing, given the success of the various FSL aerial for the mediumwave band, what would work the best on the FM band? I have found some instructions for various FM dipoles, would a look work this high?

Paul


Marc Coevoet
 

Op 10/12/2020 om 05:53 schreef Paul Blundell:
Over the upcoming Christmas break I am looking at undertaking some portable FM dxing, given the success of the various FSL aerial for the mediumwave band, what would work the best on the FM band? I have found some instructions for various FM dipoles, would a look work this high?
Paul

I have compared this with the Antiference Fm yagi, and it looks the best for 106.2 here . One of the last places to buy in Europe is ..

https://www.wifi-shop.cz/fm-antenna-iskra-fm-50-f_d10791.html?action=setcursetlng&lngid=1&curid=14

https://www.amazon.co.uk/ANTIFERENCE-Aerial-1085-Element-Boxed/dp/B00BDIVCGE


Marc
--
The "Penguin" has arrived - and he's not going away - ever.
For former Apple users: Xubuntu.org (menu's up left)
For former Windows users: Lubuntu.org (menu's down left)


Paul Blundell
 

They both look like good options, I will see if I can find anything like this locally.


On Thu., 10 Dec. 2020, 20:20 Marc Coevoet, <sintsixtus@...> wrote:
Op 10/12/2020 om 05:53 schreef Paul Blundell:
> Over the upcoming Christmas break I am looking at undertaking some
> portable FM dxing, given the success of the various FSL aerial for the
> mediumwave band, what would work the best on the FM band? I have found
> some instructions for various FM dipoles, would a look work this high?
>
> Paul


I have compared this with the Antiference Fm yagi, and it looks the best
for 106.2 here .  One of the last places to buy in Europe is ..

https://www.wifi-shop.cz/fm-antenna-iskra-fm-50-f_d10791.html?action=setcursetlng&lngid=1&curid=14

https://www.amazon.co.uk/ANTIFERENCE-Aerial-1085-Element-Boxed/dp/B00BDIVCGE


Marc
--
The "Penguin" has arrived - and he's not going away - ever.
For former Apple users: Xubuntu.org (menu's up left)
For former Windows users: Lubuntu.org (menu's down left)






Dave Hascall
 

Hi Paul.

Are you DXing for Es, tropo, or just doing a bandscan? If it's the last two, elevation is key. I know a lot of 6 meter hams will climb fire towers, hills, parking garages, and so on to get an advantage in terms of elevation.  Sporadic E doesn't need so much elevation.  Good luck.

73,
Dave in Indy (Noblesville)


Russ Edmunds
 

I think it depends on what radio you'll be using. Since you're asking the question, I'll presume that the radio you'll use has an external antenna connection.

Height and avoidance of obvious horizon blockage due to hills or structures are a good start.

A dipole is a bit difficult to work with but it can be done. If I have to choose between a dipole and rabbit ears, I'll go with the latter. For your purpose, a small collapsible FM yagi seems best - perhaps 4 or 6 elements. Then you can mount that to a short mast and anchor it with a portable tripod or even a concrete block. For portable work manual rotation is fine. I don't know what's available there, but to give you an idea, attached is some info on one I've used with some success - it's lightweight, but not to the point of being fragile.



From: main@UltralightDX.groups.io <main@UltralightDX.groups.io> on behalf of Dave Hascall via groups.io <dhinfomedia@...>
Sent: Thursday, December 10, 2020 9:24 AM
To: main@UltralightDX.groups.io <main@UltralightDX.groups.io>
Subject: Re: [UltralightDX] FM Aerials
 
Hi Paul.

Are you DXing for Es, tropo, or just doing a bandscan? If it's the last two, elevation is key. I know a lot of 6 meter hams will climb fire towers, hills, parking garages, and so on to get an advantage in terms of elevation.  Sporadic E doesn't need so much elevation.  Good luck.

73,
Dave in Indy (Noblesville)


Jorge Garzón <iberiaDX@...>
 

Hi Paul,
What's your main proposal? A local bandscan? As many stations the best? Get unusual ones? Most of the times, at least in VHF, the goal is the main clue on how to choose the aerial. A local bandscan can get the best results just using your car radio (as antenna+receiver system is probably the most efficient system to monitor the band). Most of the times I use a 5 el yagi to get the best when the Tropo or Es season start. A yagi antenna also serves me to avoid some azimuths in which I am not interested in or are where my usual stations are.

A 5 elements mounted yagi does not fit in a car so I take it on the roof or to put it in I fold one of the halves of each element, as I can loose screws and wing nuts. The dipole can be also separated easily. A 5 element yagi allows you to manage the size quickly and depending of its design, gives you a very good gain in one half of the band while decreases at the other half. Mine, with 158 cm boom is great from 87,5 to 96, good from 96 to 100 MHz and even shows an inverse gain from 104 to 108 MHz. This wouldn't happen with a longer boom, say 200 cm), but would be much more tedious to manage as now I have a very good aerial system (antenna, telescopic pole, pole base and quick guy ropes attachments). I can be operative in just 10 minutes.

I have a 5 el yagi similar to the one showed in the Czech link that gave you, and also hava another 5 el yagi (Antiference) both with very good results. VHF Band II yagis are becoming rarer and are disappearing quickly from stores. DIY projects are easy to face and usually give very good results.

Elevation is not as critical for Band II as it is for 2m VHF 144 / 432 MHz when conditions are good. For hams mountains are real walls but for FM'ers they can be very good allied!

73!



K7DWI Art
 

Good morning all from the great Northwest (Oregon).
I have been FM/TVing for decades.  But, I spend my time as a Ham.
All I can say say is, "Keep It Simple!".
For portable FM DXing, a simple set of TV Rabbit Ears measured to your frequency works great and better than anything.
You can pick up Es and Tropo and null out locals.
Attached...
A simple demo: 
https://youtu.be/69Hz1wwREFg
SASE Measurements of Rabbit Ears by Frequency
Dipole Length FMBC Attached 

73 Art K7DWI


vbifyz
 

The radio is also very important for FM DXing. In many situations, weak signals of interest are next to very strong local signals.The receiver has to handle such conditions without generating intermodulation interference, i.e. needs a high dynamic range.
I didn't play with too many FM radios, but can say that my PL-880 is very good in this respect, compared to my Ka-1102, and even compared to RTL-SDR dongles.

73, Mike AF7KR


Paul Blundell
 

Mostly just scanning the band. I have plans to get out and about at some high locations but in the meantime I am trying to improve my aerials as much as possible.

Paul

On Fri, Dec 11, 2020 at 1:24 AM Dave Hascall <dhinfomedia@...> wrote:
Hi Paul.

Are you DXing for Es, tropo, or just doing a bandscan? If it's the last two, elevation is key. I know a lot of 6 meter hams will climb fire towers, hills, parking garages, and so on to get an advantage in terms of elevation.  Sporadic E doesn't need so much elevation.  Good luck.

73,
Dave in Indy (Noblesville)



--
Paul


Paul Blundell
 

Thanks for that information, I will check them out.

Paul

On Fri, Dec 11, 2020 at 1:40 AM Russ Edmunds <wb2bjh@...> wrote:
I think it depends on what radio you'll be using. Since you're asking the question, I'll presume that the radio you'll use has an external antenna connection.

Height and avoidance of obvious horizon blockage due to hills or structures are a good start.

A dipole is a bit difficult to work with but it can be done. If I have to choose between a dipole and rabbit ears, I'll go with the latter. For your purpose, a small collapsible FM yagi seems best - perhaps 4 or 6 elements. Then you can mount that to a short mast and anchor it with a portable tripod or even a concrete block. For portable work manual rotation is fine. I don't know what's available there, but to give you an idea, attached is some info on one I've used with some success - it's lightweight, but not to the point of being fragile.



From: main@UltralightDX.groups.io <main@UltralightDX.groups.io> on behalf of Dave Hascall via groups.io <dhinfomedia=gmail.com@groups.io>
Sent: Thursday, December 10, 2020 9:24 AM
To: main@UltralightDX.groups.io <main@UltralightDX.groups.io>
Subject: Re: [UltralightDX] FM Aerials
 
Hi Paul.

Are you DXing for Es, tropo, or just doing a bandscan? If it's the last two, elevation is key. I know a lot of 6 meter hams will climb fire towers, hills, parking garages, and so on to get an advantage in terms of elevation.  Sporadic E doesn't need so much elevation.  Good luck.

73,
Dave in Indy (Noblesville)



--
Paul


Paul Blundell
 

Thanks Jorge.

I think I need to get hold of a tripod and some other aerials and see how they go, my goal is to be able to log some lower power stations from further away.

Paul

On Fri, Dec 11, 2020 at 2:04 AM Jorge Garzón via groups.io <iberiaDX=yahoo.com@groups.io> wrote:
Hi Paul,
What's your main proposal? A local bandscan? As many stations the best? Get unusual ones? Most of the times, at least in VHF, the goal is the main clue on how to choose the aerial. A local bandscan can get the best results just using your car radio (as antenna+receiver system is probably the most efficient system to monitor the band). Most of the times I use a 5 el yagi to get the best when the Tropo or Es season start. A yagi antenna also serves me to avoid some azimuths in which I am not interested in or are where my usual stations are.

A 5 elements mounted yagi does not fit in a car so I take it on the roof or to put it in I fold one of the halves of each element, as I can loose screws and wing nuts. The dipole can be also separated easily. A 5 element yagi allows you to manage the size quickly and depending of its design, gives you a very good gain in one half of the band while decreases at the other half. Mine, with 158 cm boom is great from 87,5 to 96, good from 96 to 100 MHz and even shows an inverse gain from 104 to 108 MHz. This wouldn't happen with a longer boom, say 200 cm), but would be much more tedious to manage as now I have a very good aerial system (antenna, telescopic pole, pole base and quick guy ropes attachments). I can be operative in just 10 minutes.

I have a 5 el yagi similar to the one showed in the Czech link that gave you, and also hava another 5 el yagi (Antiference) both with very good results. VHF Band II yagis are becoming rarer and are disappearing quickly from stores. DIY projects are easy to face and usually give very good results.

Elevation is not as critical for Band II as it is for 2m VHF 144 / 432 MHz when conditions are good. For hams mountains are real walls but for FM'ers they can be very good allied!

73!




--
Paul


Paul Blundell
 

Thanks Art, I think I have a spare set of these somewhere. I will start simple and see how I go.

Paul

On Fri, Dec 11, 2020 at 3:05 AM K7DWI Art <k7dwicn82@...> wrote:

Good morning all from the great Northwest (Oregon).
I have been FM/TVing for decades.  But, I spend my time as a Ham.
All I can say say is, "Keep It Simple!".
For portable FM DXing, a simple set of TV Rabbit Ears measured to your frequency works great and better than anything.
You can pick up Es and Tropo and null out locals.
Attached...
A simple demo: 
https://youtu.be/69Hz1wwREFg
SASE Measurements of Rabbit Ears by Frequency
Dipole Length FMBC Attached 

73 Art K7DWI



--
Paul


Paul Blundell
 

Thanks Mike. At this point I will be mostly using my AR-1733. If I get more serious about it, I might look at an upgrade.


On Fri, Dec 11, 2020 at 9:05 AM vbifyz <3ym3ym@...> wrote:
The radio is also very important for FM DXing. In many situations, weak signals of interest are next to very strong local signals.The receiver has to handle such conditions without generating intermodulation interference, i.e. needs a high dynamic range.
I didn't play with too many FM radios, but can say that my PL-880 is very good in this respect, compared to my Ka-1102, and even compared to RTL-SDR dongles.

73, Mike AF7KR



--
Paul


kevin asato <kc6pob@...>
 

And Paul,
with or despite all the recommendations you have received:
1) have fun!
2) let us know what you did so as i am sure you will.

i still have my 300Ohm twin lead diple that came with my stereo. it requires support but is very usable as well.

73,
kevin
kc6pob



Dave Hascall
 

Awesome, Paul.  As Russ stated, rabbit ears will work well.  I logged dozens of stations via Es with a cheap set found at a second hand store and Tropo out to 500 miles with it.

73
Dave in Indy


Paul Blundell
 

Thanks Dave.

I just picked up a set for $7, I will see how they go.

On Fri, Dec 11, 2020 at 12:59 PM Dave Hascall <dhinfomedia@...> wrote:
Awesome, Paul.  As Russ stated, rabbit ears will work well.  I logged dozens of stations via Es with a cheap set found at a second hand store and Tropo out to 500 miles with it.

73
Dave in Indy



--
Paul