General Attic Antenna Observation - Looking For Input

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Emsflyer84
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Joined: 29 Aug 2020 06:33

General Attic Antenna Observation - Looking For Input

Post by Emsflyer84 »

Hey all, I'm in Central NH and have been experimenting with antennas in my attic for better reception. Roof mount not possible currently. I have a Centerfire folded diploe tuned to the VHF High public safety bands:
https://centerfireantenna.com/folded-di ... -antennas/

I also have a commercial dual band Diamond vertical antenna:
https://www.diamondantenna.net/x50c2.html

Both are mounted in the attic next to each other. My observations using both are strange. Both work well, but the dipole picks up distant VHF analog better, more clear with less static then the Diamond. The Diamond pulls in distant VHF digital better and more consistently then the dipole, which struggles on a couple digital transmitters about 30 miles away. The Diamond seems to get them very clear. Again, with analog transmissions about the same distance away, the dipole gets them clear and the Diamond struggles and they will cut in and out and have a lot of static with the Diamond.

It seems strange to me that one antenna works better for analog, one better for digital with transmissions all in the same frequency range and at the same distance.

Anyone else experience this with different antennas? Thanks!

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ecps92
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Re: General Attic Antenna Observation - Looking For Input

Post by ecps92 »

Are you comparing the Same Freq on both antenna's ? with the same Radio ?

Different radios handle the P25 slightly different, especially with Simulcast transmitters [different sites transmitting at the same time - mostly an issue with Trunking]
Also it could be something with your cables, connections. - keep experimenting
Emsflyer84 wrote:
13 Mar 2021 08:51
Hey all, I'm in Central NH and have been experimenting with antennas in my attic for better reception. Roof mount not possible currently. I have a Centerfire folded diploe tuned to the VHF High public safety bands:
https://centerfireantenna.com/folded-di ... -antennas/

I also have a commercial dual band Diamond vertical antenna:
https://www.diamondantenna.net/x50c2.html

Both are mounted in the attic next to each other. My observations using both are strange. Both work well, but the dipole picks up distant VHF analog better, more clear with less static then the Diamond. The Diamond pulls in distant VHF digital better and more consistently then the dipole, which struggles on a couple digital transmitters about 30 miles away. The Diamond seems to get them very clear. Again, with analog transmissions about the same distance away, the dipole gets them clear and the Diamond struggles and they will cut in and out and have a lot of static with the Diamond.

It seems strange to me that one antenna works better for analog, one better for digital with transmissions all in the same frequency range and at the same distance.

Anyone else experience this with different antennas? Thanks!
Bill Dunn N1KUG
Cruise Ship Frequencies
http://scanmaritime.com

"The tougher it is to find a frequency, the more it makes me want to work to find it. - I've learned to use the SEARCH Button"

Emsflyer84
Posts: 6
Joined: 29 Aug 2020 06:33

Re: General Attic Antenna Observation - Looking For Input

Post by Emsflyer84 »

Thanks. It is the same scanner, same wiring, same everything and same frequencies. One digital frequency comes in decent with the Diamond antenna and broken and spotty with the dipole. And it's reverse with distant analog frequencies. One analog frequency comes in great on the dipole and the same frequency comes in scratchy on the Diamond on the same scanner.

JBP
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Joined: 28 Jun 2008 11:24
Location: South of Boston

Re: General Attic Antenna Observation - Looking For Input

Post by JBP »

How close is "next to each other"?

If they are within 2-3' of each other they could be distorting the patterns of both antennas. Other close metallic object in the attic or roofing material could be doing the same thing causing them to not perform like omni-directional antennas.

Roughly mapping out where the strong and weak signals are coming from for each antenna might give you an idea if this is the case or not
Jeremy
KB1REQ (DMR-MARC: 3125125)

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ecps92
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Location: South Shore, MA
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Re: General Attic Antenna Observation - Looking For Input

Post by ecps92 »

So you are going up and changing the cable from Antenna One to Antenna Two each time for testing ? Trying to get a clearer understanding.

Also as Jeremy points out, altho the two antennas are in an almost identical position, they are not
One could be shading the others reception, or there is something on the roof shielding the reception
Emsflyer84 wrote:
13 Mar 2021 12:43
Thanks. It is the same scanner, same wiring, same everything and same frequencies. One digital frequency comes in decent with the Diamond antenna and broken and spotty with the dipole. And it's reverse with distant analog frequencies. One analog frequency comes in great on the dipole and the same frequency comes in scratchy on the Diamond on the same scanner.
Bill Dunn N1KUG
Cruise Ship Frequencies
http://scanmaritime.com

"The tougher it is to find a frequency, the more it makes me want to work to find it. - I've learned to use the SEARCH Button"

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W1KNE
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Re: General Attic Antenna Observation - Looking For Input

Post by W1KNE »

And don't forget that a center folded dipole isn't truly omni directional. They tend to have pattern distortion "in-line" between the antenna and mounting pole*. Try rotating your dipole 90° on axis and see what changes.
Usually the antenna manufacturers will make the offset mount specific to minimize it, but it still occurs.

(*Example. If you have an antenna facing 270°, your reception will be affected at 90°).
Mike Fitzpatrick
Broadcast Engineer - RF Enthusiast - Municipal Fire Alarm Collector
Owner: Scan New England - NECRAT.US
Issues with Scan New England can be privately addressed to me.

ErrolW
Posts: 68
Joined: 10 Jul 2014 09:07
Location: Framingham, MA or Pittsburg, NH

Re: General Attic Antenna Observation - Looking For Input

Post by ErrolW »

If NHSP Troop F is being monitored keep in mind there is simulcast on 154.6800 (and maybe other frequencies...I can't keep up).
Most scanners don't seem to do well with this.

Fish and Game also has multiple transmit locations on 151.3400, but I doubt this is an issue in central NH. Up north its a big PITA.
Errol
Framingham, MA
Pittsburg, NH

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