Our local highway patrol seems to put all their antennas as close to each other, on the same ground plane. It's almost as if they're trying to use a phased array 😆
Thank you for this tutorial. I want two scanners in my SUV so this is a receiving only question. Can I have the same type of antennas for both radios or do I have to follow the same guidelines that you talk about for receive and transmit? Also, do mag mounts cause more interference vs ones that get installed through the roof?
You can run the same style with no issues since they’re receive only. Permanent NMO mount antennas are the better option if you’re able to do so on your particular vehicle.
Another question. Unlike quarter-wave antennas, half-wave antennas (with impedance matching) don't *need* a ground plane. One might be an answer to a 'where do I put in issue?' They could be put more places. But not needing a ground plane isn't the same as not benefiting from one to have a consistent, low-angle radiation pattern. Is the radiation pattern of a half-wave antenna influenced by the ground plane under it?
Random question. All the emergency services agencies in my county have pretty much the same install, and without being able to post a picture, I’ll try to explain it. They all use UHF for P25 and VHF analog, so only 2 antennas. The Ford Police Utility example is the most common, but the method makes me scratch my head about the ground plane. They have the UHF 1/4 wave mounted dead center of the roof, and the VHF 1/4 wave straight behind it about 4 feet apart. But the VHF is also less than 1 foot from the factory AM/FM stereo antenna. Would it not make a better ground plane for each to have to VHF in the middle and the UHF toward the rear? Obviously the V needs a larger diameter ground plane than the U does. And they use the same method on crew cab F150s. UHF is dead center behind lightbar but VHF is at the rear of the cab just a couple inches from the third brake light. Wouldn’t that limit the V at the rear to only having a semi-circle ground plane toward the front half of the vehicle and none toward the rear? I’m no expert, but with my limited knowledge it doesn’t look right to me. 🤷🏻♂️
Good question. Not sure that the order/placement of the antennas matters too much as it relates to the Pyramid setup, but general antenna placement good practices still should apply and i would tend to agree with you. At the end of the day, you have to wonder if someone at the agency have maybe has already done testing to come up with the method they have the antennas mounted and they have data to backup their installation - or maybe not. Who knows, but the placement of the Pyramid antenna vs the mobile antenna in this case wouldn't effect the pyramid operation, however, i would probably suggest putting that Pyramid antenna on a separate ground plane completely, such as the hood, or bumper with a lip mount or mounted to the push bar. Doesn't sound like they have a Pyramid in this case, but if they did... more separation is better even if you have to sacrifice a good ground plane for the Pyramid.
Great advice! A question. Does Pyramid make bandpass filters to deal with this issue? I ask because at one time as a radio ham I had a 2-meter system in my car and worked at USAF radar sites that had multiple megawatt radars operating. To protect the front end of my radio I placed a shorted quarter-wave coax stub at the antenna connector. That looked like at open at 2 meters and for any odd harmonic. It looked like a short for even harmonics and a partial short at other frequencies. It seems like similar bandpass filters could prevent some of this desensitization.
For a VHF SVR antenna, would the Phantom antenna be a better or same choice of antenna as the "soup can" (Mirage) antenna? I believe your point is to use a different type than the mobile antenna, however, I'm wondering about the differences of these two type of antennas.
It's more about the different type of antenna vs. a phantom over a soup-can type. The point is, two quarter-wave antennas can be more problematic. We have no preference and have done no testing on performance on a phantom vs a soup-can style.
I was curious about having CB antenna and a scanner antenna on the roof of a pick up truck only about 10 inches apart. I was told there should be no issue transmitting on the CB and causing any problem to the scanner since the CB is only 4 watts and 12 watts on SSB. I've had it this way for many years and haven't noticed any problem with either radio. Any thoughts would be appreciated. Thank you.
As a general rule, i would still never recommend 10" of separation between a transmit antenna and a receiver antenna (in your case the scanner). Though the CB is only 4 watts in AM, the scanner has virtually zero protection on the front-end filter. By nature the scanner is wide band. Your risk is, if you overload the receiver pre-amp on the scanner enough, you can damage it and lessen the receive sensitivity of the scanner. Further, lower frequency stuff (like CB or Low-Band VHF) can do a surprisingly significant amount of damage to pre-amps. The further you can get the antennas the better, always.
Our local highway patrol seems to put all their antennas as close to each other, on the same ground plane. It's almost as if they're trying to use a phased array 😆
Great information
And yet simplex gateways are limited to 5w ERP!! I don't understand that.
Thank you for this tutorial. I want two scanners in my SUV so this is a receiving only question. Can I have the same type of antennas for both radios or do I have to follow the same guidelines that you talk about for receive and transmit? Also, do mag mounts cause more interference vs ones that get installed through the roof?
You can run the same style with no issues since they’re receive only. Permanent NMO mount antennas are the better option if you’re able to do so on your particular vehicle.
Another question. Unlike quarter-wave antennas, half-wave antennas (with impedance matching) don't *need* a ground plane. One might be an answer to a 'where do I put in issue?' They could be put more places. But not needing a ground plane isn't the same as not benefiting from one to have a consistent, low-angle radiation pattern. Is the radiation pattern of a half-wave antenna influenced by the ground plane under it?
Half wave dosent need matching either
Random question. All the emergency services agencies in my county have pretty much the same install, and without being able to post a picture, I’ll try to explain it. They all use UHF for P25 and VHF analog, so only 2 antennas. The Ford Police Utility example is the most common, but the method makes me scratch my head about the ground plane. They have the UHF 1/4 wave mounted dead center of the roof, and the VHF 1/4 wave straight behind it about 4 feet apart. But the VHF is also less than 1 foot from the factory AM/FM stereo antenna. Would it not make a better ground plane for each to have to VHF in the middle and the UHF toward the rear? Obviously the V needs a larger diameter ground plane than the U does. And they use the same method on crew cab F150s. UHF is dead center behind lightbar but VHF is at the rear of the cab just a couple inches from the third brake light. Wouldn’t that limit the V at the rear to only having a semi-circle ground plane toward the front half of the vehicle and none toward the rear? I’m no expert, but with my limited knowledge it doesn’t look right to me. 🤷🏻♂️
Good question. Not sure that the order/placement of the antennas matters too much as it relates to the Pyramid setup, but general antenna placement good practices still should apply and i would tend to agree with you. At the end of the day, you have to wonder if someone at the agency have maybe has already done testing to come up with the method they have the antennas mounted and they have data to backup their installation - or maybe not. Who knows, but the placement of the Pyramid antenna vs the mobile antenna in this case wouldn't effect the pyramid operation, however, i would probably suggest putting that Pyramid antenna on a separate ground plane completely, such as the hood, or bumper with a lip mount or mounted to the push bar. Doesn't sound like they have a Pyramid in this case, but if they did... more separation is better even if you have to sacrifice a good ground plane for the Pyramid.
Which of your antennas will work for gmrs since i live in the middle of the woods thanks!!
What is the beat low profile GMRS car antenna? Everyone on youtube I see uses the “ghost” antenna.
Great advice! A question. Does Pyramid make bandpass filters to deal with this issue? I ask because at one time as a radio ham I had a 2-meter system in my car and worked at USAF radar sites that had multiple megawatt radars operating. To protect the front end of my radio I placed a shorted quarter-wave coax stub at the antenna connector. That looked like at open at 2 meters and for any odd harmonic. It looked like a short for even harmonics and a partial short at other frequencies. It seems like similar bandpass filters could prevent some of this desensitization.
Yes, they do
I call but nobody answers the phone!!
Will the SVR 200 Pass P25 Simplex?
For a VHF SVR antenna, would the Phantom antenna be a better or same choice of antenna as the "soup can" (Mirage) antenna? I believe your point is to use a different type than the mobile antenna, however, I'm wondering about the differences of these two type of antennas.
It's more about the different type of antenna vs. a phantom over a soup-can type. The point is, two quarter-wave antennas can be more problematic. We have no preference and have done no testing on performance on a phantom vs a soup-can style.
I was curious about having CB antenna and a scanner antenna on the roof of a pick up truck only about 10 inches apart. I was told there should be no issue transmitting on the CB and causing any problem to the scanner since the CB is only 4 watts and 12 watts on SSB. I've had it this way for many years and haven't noticed any problem with either radio. Any thoughts would be appreciated. Thank you.
As a general rule, i would still never recommend 10" of separation between a transmit antenna and a receiver antenna (in your case the scanner). Though the CB is only 4 watts in AM, the scanner has virtually zero protection on the front-end filter. By nature the scanner is wide band. Your risk is, if you overload the receiver pre-amp on the scanner enough, you can damage it and lessen the receive sensitivity of the scanner. Further, lower frequency stuff (like CB or Low-Band VHF) can do a surprisingly significant amount of damage to pre-amps. The further you can get the antennas the better, always.
@@pyramidcomm Thank you very much for your reply.
What about fiberglass roofs
I would suggest a glass mount antenna for the Pyramid or (perhaps better) move the Pyramid antenna to the hood with a lip-mount.