Hey guys a few questions i have a 35 foot bus aluminum skinned and i have a siro 5000 mobile antenna where do i put it ..in the middle on the roof puck mount ? gutter mount / mirror / but its got a long stringer on it but i thought the coil needs to be above the bus or do i just need a short antenna ? what would be best ? i am lost with such a tall vehicle thanks...
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BUS Antenna placement
- Thread starter James Rich
- Start date
I drove charter bus for a while. 40 ft Vanhool. You need to keep the top down around 13ft 6 inches. Don't know how tall the body is, but you want to get the coil above it. If you can't, then get it as far from the body as possible. Joe Walsh used to lose antennas of the back of tour buses all the time.
Rich
Rich
its 10 foot tall i was thinking of just mounting it right on top with a puck and bolting it threw the steel framing and let the stinger bump what ever it wants lol
If it was my bus, I would use the trucker-style method that has been used for decades and is easily available and relatively cheap. Mirror mount dual antennas with the dual antenna harness is bulletproof and won't cause a height clearance problem like you will face without remedy with a snigle antenna on the roof . . .
JMHO . . .
JMHO . . .
i thought about doing that with 2 gutter mounts and a co phase set up i read somewhere some one said gutter mounts are not any good the mirrors are at too different heights and i wont be able to get the coil above the roof gutter mounts i could but still puts the Antennas pretty high does it really madder much if there a little too tall they are really flimsy should just bend over easily if i hit something
Going on top a bus that is 10ft. The sirio 5k is I believe 6.5 ft tall plus your puck mount..that's pushing 17 ft. Overpasses on interstates are in the range of 16 ft tall...I think 14 minimum height. At 60+ mph that could do some radical damage to the whip. Steel and concrete are not very forgiving at that speed. Just my .02....
i might have to lean them forward off the gutter which is about 24 inches lower then the roof but the coils wont be above the roof line ? humm
the drivers side mirror is at the bottom of the windshield lol i don't know where to put them mount them lower on the side of the bus but again the coils any thoughts ? i do appreciate you guys taking the time to help me get this figured out
If you don't mind drilling consider a couple ball type mounts on the side near the top, top loaded antennas would alleviate the coil height problem.
I agree that 10ft is to tall. I ran a Sirio performer 5k on a Nissan work van that was a high back. It was about 9ft to the top. I didn't hit many bridges with it, but at slower speeds on back roads it would hit every tree branch that stuck out if I disnt avoid a lot of them!! I had a mag mount setup, but a low profile hard mount won't stick up any further than the magnet mount did.
But like I said, 10ft you are going to be hitting every bridge with any kind of decent antenna. Might consider what StrangeBrew posted, or maybe mount onto the mirrors and just get the coil above the roof. Lean it forward a couple degrees and it will stand back just enough to avoid most objects. And when I say a bit f forward lean, not like the truckers do and place them at a 45 degree angle LOL. Just a touch forward. Do dual Sirio trucker series performer 5k's. That should work perfect looking at your mirrors. You can get longer bottom shafts from Wilson. Or at least I think you can. I'm sure someone sells bottom shafts for center or near center loaded antennas. JMHO. Even one antenna on the drivers side would work. But with the room you have, a dual setup might just work pretty good. Again, JMHO, and I am no antenna expert nor have I mounted antennas onto a truck of that size, but height wise I was within a foot of your roof anyways. So that I do understand. Like said l, you'll destroy the whip after a few good hits the tip will end up looking like a small box almost LOL! Been there. Up around Chicago, IL area the brigdes are not very tall and I travelled from Grand Rapids, Michigan. By the time I got to where I was going which was outside Milwaukee, WI, the tip of my antenna was bent into a small square at the tip. I had a heck of a time getting back straight. Just to return back the same way LOL! Had to order a new whip by the time I got home to FL.
Good luck and keep us posted as to where you mount the antennas.
Also is you wanted you could add a good hard mount on top like a 3" single hole Breedlove mount and put an antenna up when you are parked. Place the antenna center of that roof and you have a great ground plane with all the steel if that is what it is on top. Add a 108" whip or a 102" whip and riser and have a sweet static setup as well. Just some food for thought. Good luck with whatever you do. And be safe!!
But like I said, 10ft you are going to be hitting every bridge with any kind of decent antenna. Might consider what StrangeBrew posted, or maybe mount onto the mirrors and just get the coil above the roof. Lean it forward a couple degrees and it will stand back just enough to avoid most objects. And when I say a bit f forward lean, not like the truckers do and place them at a 45 degree angle LOL. Just a touch forward. Do dual Sirio trucker series performer 5k's. That should work perfect looking at your mirrors. You can get longer bottom shafts from Wilson. Or at least I think you can. I'm sure someone sells bottom shafts for center or near center loaded antennas. JMHO. Even one antenna on the drivers side would work. But with the room you have, a dual setup might just work pretty good. Again, JMHO, and I am no antenna expert nor have I mounted antennas onto a truck of that size, but height wise I was within a foot of your roof anyways. So that I do understand. Like said l, you'll destroy the whip after a few good hits the tip will end up looking like a small box almost LOL! Been there. Up around Chicago, IL area the brigdes are not very tall and I travelled from Grand Rapids, Michigan. By the time I got to where I was going which was outside Milwaukee, WI, the tip of my antenna was bent into a small square at the tip. I had a heck of a time getting back straight. Just to return back the same way LOL! Had to order a new whip by the time I got home to FL.
Good luck and keep us posted as to where you mount the antennas.
Also is you wanted you could add a good hard mount on top like a 3" single hole Breedlove mount and put an antenna up when you are parked. Place the antenna center of that roof and you have a great ground plane with all the steel if that is what it is on top. Add a 108" whip or a 102" whip and riser and have a sweet static setup as well. Just some food for thought. Good luck with whatever you do. And be safe!!
And they perform like shit. The mirror arms provide no ground, the spacing of the antennas is barely sufficient for co-phasing and it turns your signal into one with a pattern that is from left to right and far less omnidirectional so you could be talking to someone with say a S5, turn a right corner and find you can't hear them anymore.
The bus in the pic is metal, so assuming there is a properly bonded connection between the mirror mounts and the bus' outer shell, there will be plenty of ground plane. Further, with a set of "co-phased" antennas you don't need as much ground plane as a single antenna, they work off of each other to a point... That is not to sat that the antennas won't perform better with more ground plane, but to get "co-phased" antennas to function, you don't have to have as much.
Which is it, is the proposed antenna setup is barely enough for co-phasing, or is it enough that you will get such a drastic difference that an s5 signal will no longer be heard simply because you made a turn? You can't have both as a result of "co-phasing", they are mutually exclusive results so at best it will be one or the other. So which is it?
Now I'm not a fan of "co-phasing", in my experience in *most* cases a single antenna mounted along the center line between the "co-phased" antennas will generally perform just as well. I say most because I have a model of my Ford Explorer where such antennas in a certain position actually nearly got 2 dB more gain towards the front compared to a single antenna mounted on the roof on the middle line between said dual antennas. This is not enough to make an S5 signal unhearable because of a turn. No other "co-phased" model on said vehicle did that, and it wasn't expected in the first place. It was more a result of antenna placement than weather or not the antennas were "co-phased"...
If you have two "co-phased" antennas at 1/4 wavelength apart, the ARRL antenna books 15'th edition and newer clearly state than you can expect to see 1.1 dB gain over a single identical antenna mounted between them. You can mount them closer together, although the small amount of gain they can provide drops. You can have a set a few inches apart and still call them "co-phased' if you want, even though they will ultimately perform like a single antenna. This gain will also be broadside of the antennas, or if they are mounted on a vehicles mirrors, gain will be towards the front and back of the vehicle, not to the left and right sides of the vehicle. Modeling confirms both of these. Modeling has also demonstrated, at least to me using my Ford Explorer model, that the shape and size of the vehicle, and where the antennas are mounted on said vehicle, may well have more of an effect on the radiation pattern than the antennas themselves, and weather or not they are a single antenna or a "co-phased" set...
I don't know that I would suggest jumping directly into "co-phasing", I'm not a fan of it and never have been. On a vehicle it adds a bit of complexity, and more failure points, all for gains that you will rarely if ever notice... For that bus, if anything, I would say try as many different setups (as in antenna mounting locations) as you can over time and see how they work for you.
The DB