PART #2 When I went in on 440 the Kenwood mobile wood transmit on the 220 simplex frequency back to him. It was cool. The three foot separation worked with no problems, 20 watts on 220, 30 watts on 440. This was early 1990's so there was no computers. I went to Radio Shack and bought those little engineering pamphlets they used to have for I think 50 cents and figured out how to build the necessary controller to do the job. I plan on moving back to that acreage soon, it is an excellent radio location. Best contact from there is 50 miles on a 440 repeater using a Kenwood TH-41AT, 1 watt HI, 150 mw low. I contacted and talked on the repeater on 150 mw with the rubber antenna in side the house.
PART #1 Separation and frequency choice is key. I used to talk to friend a long time ago on 220 simplex. We could talk any time of the day, I used a Cushcraft seven element beam mounted vertical on the one side of the tower 30' up. The friend had a home brew 220 beam and his was up 30'. Our simplex path was 75 miles, transmission FM. I also had a 220 repeater at my site also. I had a 440 repeater as well. My friend was a novice so 220 was the all he had. I had a 440 repeater antenna mounted three feet away from the 220 beam and my friend could be received on a 220 simplex frequency on the Kenwood mobile that would trigger my 440 repeater and I could talk to him. GO TO PART #2
I think that everyone has missed the right answers. Sure, what has been said works, but reality has some difference. For a VHF and a UHF, they can both be on the SAME antenna, no separation needed. For adjacent VHF, it depends on how much desense you can tolerate. In most operator's situations, you can accept quite a bit. The most important number is how much energy can your receivers accept before they are damaged, and that is quite a bit. This isn't generally a problem with VHF/UHF radios unless you start adding some large amplifiers to them. The answer often becomes how close you can effectively mount the antennas. You'll see communications vans with antennas on grid points often around 1-2 ft apart. To get back to the specifics of the direction that the hosts were referring to, you have to start with the frequencies. And yes, if you change a frequency, you invalidate most of the calculations. So starting down that path isn't the greatest way. But if you look at the frequencies, you start to notice some interesting artifacts. You may think that one radio on 145.05 and another on 145.07 may be too close, but their transmitters are at 145.65 and 145.67, either one is about 0.6 MHz away from each other. It is a complicated answer and my general recommendation is to keep as far as part as possible, putting in different vertical planes if possible. But remember that if you separate two by 500 ft, while the desense will be decreased, the coax loss is going to kill you.
That would work by using a duplexer if the antenna was a VHF/UHF dual band and not a single band antenna. I'm sure you were just using those frequencies as examples, but 145.05 and 145.07 are packet frequencies. I actually have two Winlink gateways on those same frequencies, one is packet and the other is VARA. The packet gateway gets into the VARA gateway radio, but the VARA never gets into the packet gateway radio.
How far away from a metal pole that you are mounting your UHF/VHF antenna on should that antenna be? If you are going to start stacking antennas, you can only have one antenna at the tippy top and the other stacked antennas have to be lower on the mast/tower.
New HAM...looking to get a shack-in-the-box setup like a FT-991A and run two vertical antennas (one HF and one VHF/UHF). The HF antenna will be much taller than the UHF/VHF antenna and allow me to pick up 80 to 10 meters. I'm looking at keeping them about six feet apart on the same section of my roof (just outside the shack). Anyone see any issues with this approach?
Wow, that site is a treasure trove - Thank you! 2 wavelengths of the Higher or lower band antenna? I will watch the rest hoping you make that distinction.
OK so if I had a UHF/VHF antenna and an HF antenna both are verticals, can I mount them on the same mast one above the other? Which one should be on top? This video is a good video because I have limited space but can run one mast only. But I am not certain that what was talked about covers my situation. Thanks!
Typically you'll want to mount the VHF/UHF antenna above the HF antenna as you'll want the height for the VHF antenna to be effective. Height isn't as much of an issue with HF. But putting an HF and VHF vertical on the same mast may introduce other issues that are beyond the scope of this video. Bottom line, it will depend on what HF vertical antenna you are looking at and if it will be compatible with a VHF/UHF antenna on the same mast.
The coax for the higher antenna will run up the mast past the lower antenna, so it would be good to mount the lower antenna away from the mast on a stand-off. I'm not sure how far away you would need to get the lower antenna away to not couple with the higher antenna's coax though.
If I run a HF antenna like a 20m dipole line along side my 2m/70cm JPole, (maybe 2 away or so) would it have any negative effects on either antenna? I would not be running them at the same time. My JPole is working great in my attic and I’m wanting to set up an HF antenna up there as well.
It can depend. Typically you can put a VHF/UHF above an HF wire antenna without much of an issue, but depending on location and type of the antenna, you may need to increase the spacing. There isn't often a solid answer, and you may need to experiment a bit to find a solution.
How about antennas on a vehicle? I have a CB antenna on an NMO lip mount on the driver's side of my truck's hood at the back, and the factory stereo antenna on the opposite side. I intend to put a GMRS mobile, and a dual-band mobile in the truck. I intend to put their antennas on L brackets between the fenders and hood. How far apart can they all be? I could do roof-mounted antennas, but I'm hesitant to drill holes in the roof.
Hey guys, I currently have a 10/11m vertical antenna mounted on the roof of my house. It's 17' I think. I want to put another vertical HF antenna using a 4' standoff bracket on the same antenna mast. I will only be using one radio at a time. Will this work? Will the 4 foot separation be enough? I really don't have any other options available to mount another vertical. Thanks for your advice.
I do not know the primary source of the graphs. But there is a reference on the web page if you wish to search back to their source: www.repeater-builder.com/antenna/separation.html
PART #2 When I went in on 440 the Kenwood mobile wood transmit on the 220 simplex frequency back to him. It was cool. The three foot separation worked with no problems, 20 watts on 220, 30 watts on 440. This was early 1990's so there was no computers. I went to Radio Shack and bought those little engineering pamphlets they used to have for I think 50 cents and figured out how to build the necessary controller to do the job. I plan on moving back to that acreage soon, it is an excellent radio location. Best contact from there is 50 miles on a 440 repeater using a Kenwood TH-41AT, 1 watt HI, 150 mw low. I contacted and talked on the repeater on 150 mw with the rubber antenna in side the house.
Holy cow. I love you for directing me to this page.
PART #1 Separation and frequency choice is key. I used to talk to friend a long time ago on 220 simplex. We could talk any time of the day, I used a Cushcraft seven element beam mounted vertical on the one side of the tower 30' up. The friend had a home brew 220 beam and his was up 30'. Our simplex path was 75 miles, transmission FM. I also had a 220 repeater at my site also. I had a 440 repeater as well. My friend was a novice so 220 was the all he had. I had a 440 repeater antenna mounted three feet away from the 220 beam and my friend could be received on a 220 simplex frequency on the Kenwood mobile that would trigger my 440 repeater and I could talk to him. GO TO PART #2
I think that everyone has missed the right answers. Sure, what has been said works, but reality has some difference.
For a VHF and a UHF, they can both be on the SAME antenna, no separation needed.
For adjacent VHF, it depends on how much desense you can tolerate. In most operator's situations, you can accept quite a bit. The most important number is how much energy can your receivers accept before they are damaged, and that is quite a bit. This isn't generally a problem with VHF/UHF radios unless you start adding some large amplifiers to them.
The answer often becomes how close you can effectively mount the antennas. You'll see communications vans with antennas on grid points often around 1-2 ft apart.
To get back to the specifics of the direction that the hosts were referring to, you have to start with the frequencies. And yes, if you change a frequency, you invalidate most of the calculations. So starting down that path isn't the greatest way.
But if you look at the frequencies, you start to notice some interesting artifacts. You may think that one radio on 145.05 and another on 145.07 may be too close, but their transmitters are at 145.65 and 145.67, either one is about 0.6 MHz away from each other.
It is a complicated answer and my general recommendation is to keep as far as part as possible, putting in different vertical planes if possible. But remember that if you separate two by 500 ft, while the desense will be decreased, the coax loss is going to kill you.
That would work by using a duplexer if the antenna was a VHF/UHF dual band and not a single band antenna. I'm sure you were just using those frequencies as examples, but 145.05 and 145.07 are packet frequencies. I actually have two Winlink gateways on those same frequencies, one is packet and the other is VARA. The packet gateway gets into the VARA gateway radio, but the VARA never gets into the packet gateway radio.
Good information. Thanks!
How far away from a metal pole that you are mounting your UHF/VHF antenna on should that antenna be? If you are going to start stacking antennas, you can only have one antenna at the tippy top and the other stacked antennas have to be lower on the mast/tower.
New HAM...looking to get a shack-in-the-box setup like a FT-991A and run two vertical antennas (one HF and one VHF/UHF). The HF antenna will be much taller than the UHF/VHF antenna and allow me to pick up 80 to 10 meters. I'm looking at keeping them about six feet apart on the same section of my roof (just outside the shack). Anyone see any issues with this approach?
Great video, how far apart gmrs & cb antennas should be on a tower
Wow, that site is a treasure trove - Thank you! 2 wavelengths of the Higher or lower band antenna? I will watch the rest hoping you make that distinction.
The general rule is 2 wavelengths of the lower frequency antenna.
I can use this information. I want one for my normal repeater use and one for Echolink!
OK so if I had a UHF/VHF antenna and an HF antenna both are verticals, can I mount them on the same mast one above the other? Which one should be on top? This video is a good video because I have limited space but can run one mast only. But I am not certain that what was talked about covers my situation. Thanks!
Typically you'll want to mount the VHF/UHF antenna above the HF antenna as you'll want the height for the VHF antenna to be effective. Height isn't as much of an issue with HF. But putting an HF and VHF vertical on the same mast may introduce other issues that are beyond the scope of this video. Bottom line, it will depend on what HF vertical antenna you are looking at and if it will be compatible with a VHF/UHF antenna on the same mast.
The coax for the higher antenna will run up the mast past the lower antenna, so it would be good to mount the lower antenna away from the mast on a stand-off. I'm not sure how far away you would need to get the lower antenna away to not couple with the higher antenna's coax though.
How about a 2mter 70 cm yagi vertical next to my tv antenna (horizontal) Thank you!
Hello,Do you remember TinySA Spectrum Analyzer? Looking forward to seeing video review online.
Handy to know before installation. 😁👍
If I run a HF antenna like a 20m dipole line along side my 2m/70cm JPole, (maybe 2 away or so) would it have any negative effects on either antenna? I would not be running them at the same time. My JPole is working great in my attic and I’m wanting to set up an HF antenna up there as well.
if to close they may couple with each other and throw off both antennas. Near field is tricky.
It can depend. Typically you can put a VHF/UHF above an HF wire antenna without much of an issue, but depending on location and type of the antenna, you may need to increase the spacing. There isn't often a solid answer, and you may need to experiment a bit to find a solution.
How about antennas on a vehicle? I have a CB antenna on an NMO lip mount on the driver's side of my truck's hood at the back, and the factory stereo antenna on the opposite side. I intend to put a GMRS mobile, and a dual-band mobile in the truck. I intend to put their antennas on L brackets between the fenders and hood. How far apart can they all be? I could do roof-mounted antennas, but I'm hesitant to drill holes in the roof.
100 ft apart
Thank you
Hey guys, I currently have a 10/11m vertical antenna mounted on the roof of my house. It's 17' I think. I want to put another vertical HF antenna using a 4' standoff bracket on the same antenna mast. I will only be using one radio at a time. Will this work? Will the 4 foot separation be enough? I really don't have any other options available to mount another vertical. Thanks for your advice.
no. bad idea
What about a 220 antenna besides a imax2000 antenna for hf?
I wanted to post but something or someone is stopping me. Tried for two days.
Do you know which textbook those graphs are from? Asking for a friend.
I do not know the primary source of the graphs. But there is a reference on the web page if you wish to search back to their source: www.repeater-builder.com/antenna/separation.html