Antenna for Winnebago

[SpugEddy]

Looked all over and this seems to be the best place to post.
I recently bought a 30' Winnebago and I'm installing a CB
radio and a quad band radio.
The CB antenna should be a no brainer since I'm using a 102"
whip with spring. No ground plane needed.

The quad bander isn't anything special either. I have a Browning
BR-136 tri-band antenna.

Here is my question; The RV has a ladder in the back. The ladder
rails turn from vertical to horizontal at the top of the RV. I want to
mount the Browning on the horizontal part of the ladder rail.
I can't seem to find exactly what I need to do that. It needs to be
NMO since that's what the antenna is. Has anybody here done this?
Anybody here able to picture what I have and make a suggestion?

 

[mmckenna]

A 102" whip is quarter wave on the CB bands and does need a ground plane to work correctly.
On a motorhome, attaching an antenna can be a challenge. A 1/2 wave/NGP type CB antenna off the mirror (or mirrors) would be a solution.
Mounting a 102" whip off the rear or front is going to result in some undesired performance, either the RV siding will be aluminum, or it'll be fiberglass with an aluminum frame underneath. That can make tuning difficult and create some coverage issues.

Roof top mounts will work, but you really need to be aware of the overall height. My toy hauler trailer is about 12' 6" at the AC unit and there are places I go with 13 - 14 foot clearance bridges. Add in low tree branches, and it can be an issue.

For an NMO mount off the ladder, you can fabricate something pretty easily with some flat aluminum stock, some U-bolts and the NMO mount. Ground plane, again, becomes a challenge.
https://www.theantennafarm.com/catalog/laird-technologies-lbm9034-3853 for off the vertical part of the ladder.
Or,
https://www.theantennafarm.com/cata...racket-mounts-268/nmo-straight-brackets-1514/ for coming off the horizontal part of the ladder.

Personally I'd probably fabricate my own mount using some 2" wide flat aluminum stock and a couple of stainless steel U-bolts.

 

[SpugEddy]

Thank you for the reply MMckenna.

Can't mount onto the mirrors because they are fiberglass. As is the rest
of the Winnebago. All fiberglass. Rooftop is also out of the question
because it's all fiberglass.

Now, understand this is not an argument to your statement because
your input carries a lot of weight with me. But years
back I had a 1988 Ford Clubwagon Van. I mounted a 102" whip to the
rear bumper and used a tie wrap to make a loop at the gutter of the van.
It wasn't pulled tight and it let the antenna move within the loop. As far
as I know there was no real "ground plane" since there was only metal
on one side of the antenna. I never had a problem with coverage nor
tuning.
Q: Is there something different at play here?
My plan is to make sure the ladder has a solid ground to the chassis
of the RV, which would make the ladder an ideal spot for antenna
mounting.
Q: Am I thinking correctly here?

Again, the 102" would be mounted on the vertical just resting
on the second rung of the ladder. That will put me just above
the air conditioner.
Q: is there anything I can do to create a ground plane for the whip?

Thank you
-jim

 

[W5lz]

Probably the 'best' thing would be to mount both antenna at the top of that ladder. Except there went your clearances. Don't know what to tell you about that CB whip, but I can say that mounting the 2 meter antenna shouldn't be much problem, even with an NMO mount. One solution would be an 'L' bracket eith an NMO sized hole. The other leg of the bracket can be 'U'-bolted to the ladder on top or at the top. if that antenna is fairly 'whippy' I wouldn't worry much about clearances. The metal ladder should provide enough 'ground plane' for it.

 

[mmckenna]

Q: Is there something different at play here?
My plan is to make sure the ladder has a solid ground to the chassis
of the RV, which would make the ladder an ideal spot for antenna
mounting.

Your previous statement about the van, it probably worked just fine because the antenna base was grounded at the bumper. The van body/chassis was the ground plane.

You can do the same thing on the RV, mount off the bumper or ladder, it'll work. Ideally you want to make sure that whatever you mounted it to was grounded to the chassis/body, whatever, to make the ground plane as large as possible. Do not assume the ladder is grounded to the frame. I've discovered that most of these RV's are slapped together with glue and self tapping screws.

Q: Am I thinking correctly here?

I think you are doing the best you can, and my previous post didn't convey that.
1. It's a CB. You want it to work well, but it's still a CB.
2. You are limited in what you can do on an RV, anything is going to be a challenge. We do the best we can with what we are given.
3. It's a CB. People have been doing less than ideal installs for years and they work.

With a 102" whip, there isn't much you can do. Put it together, see if it works to your satisfaction, that's what matters.
If it is a problem and you need to figure something else out, they do make no ground plane antennas that were often designed for RV's and fiberglass boats. Might be a bit harder to find, though.

Again, the 102" would be mounted on the vertical just resting
on the second rung of the ladder. That will put me just above
the air conditioner.
Q: is there anything I can do to create a ground plane for the whip?

Thank you
-jim

We'll, it would be hard to get a theoretically perfect ground plane, in fact, it's impossible to do on a road legal vehicle, the RV would need to be 18 feet wide, in otherwords, 1/4 wave in each direction under the antenna.
So, like I said, you do the best you can.
Making sure the ladder is grounded is a good start. maybe run a braid from the antenna mount to the chassis, too. If you can find something that's attached to the RV frame under the fiberglass you might connect there, also.

 

[mmckenna]

So, if you don't mind me asking, why the 102" whip?

 

[SpugEddy]

So, if you don't mind me asking, why the 102" whip?

Only because of my past experience with the van
and I have the whip in hand. I've looked around
and I'm not opposed to a firestick.

 

[mmckenna]

Only because of my past experience with the van
and I have the whip in hand. I've looked around
and I'm not opposed to a firestick.

The do make 1/2 wave fiberglass antennas that might be a better choice.

 

[SpugEddy]

I just found a Firestik 5/8 wave NGP (no ground plane)
antenna. It appears that it's the preferred antenna for
the RV owner. Starting to refocus on this one. I'll update.

lots of great suggestions that have opened some doors
MMckenna. Thank you again.

 

[mmckenna]

I've gotta mount a 1/4 wave on top of my toy hauler, but haven't got around to it yet. I'm not looking forward to it, though. Since I only need it when I'm parked, I've thought about setting up a pole off the ladder to temporarily support a base antenna. Not sure which way I'll go. I've got some free time on my hands, so maybe pulling it over to the house for a weekend is in order.

 

[SpugEddy]

MMckenna.... what is your opinion on glass mount antennas?
I know it's not my preference, but then again I'm not trying
to transmit 30 miles while I'm driving on the road. This antenna
is only for car to car use while driving to and from our destinations.

Today my wife and I went to the RV to do a few things. As I was
on the phone with a friend talking about the antennas, I got the
stink eye from her. I knew exactly what it was for but asked, "What?"
anyway. She doesn't want the RV "junked up" with radio nonsense.
So, i showed her how neat everything was and she's OK with that.
A nice glass mount antenna right above the radios would really
look nice, but I have no idea how they work. If I can get a few miles
with it, that'll be fine.

Feelings or opinions?

 

[mmckenna]

If I can get a few miles
with it, that'll be fine.

Feelings or opinions?

I doubt you'll get a few miles. I'd say be happy if you get a mile with an on-glass antenna for CB.
The antennas are electrically short, so they are already hampered.
If there is any tinting on the window, it's going to have issues. They are not good performers, at all.

If car to car is your plan, go with GMRS.

 

[SpugEddy]

I'm sorry, I should have been clearer.
The glass mount antenna would be for the GMRS radio.
We will use MURS when we hit interference.

The CB antenna is still going in the rear of the RV on
the ladder. I found good reviews for the Firestik No Ground
Plane antennas. Again, I'm not looking to Xmit 20 miles
on either antenna.

No tinting on the side window (driver's side)

Funny thing is, I see some people raving over glass mount
antennas. They claim that they work flawlessly and have
amazing range. I wonder if they love them because of
how easy they are to install. Either way, Larsen or Laird
makes a dual bander for just about $120 +/-. EHam has
a review and all of the hams give it an average of 4.4 / 5
rating.

 

[N4GIX]

I've gotta mount a 1/4 wave on top of my toy hauler, but haven't got around to it yet. I'm not looking forward to it, though. Since I only need it when I'm parked, I've thought about setting up a pole off the ladder to temporarily support a base antenna. Not sure which way I'll go. I've got some free time on my hands, so maybe pulling it over to the house for a weekend is in order.

Our EOC trailer has a 10' mast secured to the ladder on the rear of the trailer. When parked on site, another 10' mast section with the antenna(s) pre-installed is slipped onto the mounted mast, cables connected and we're ready to go. The whole evolution takes less than two minutes.

Along the roof line on both sides of the trailer there are 10' long stainless steel U shaped channels in which all of the other antennas for the EOC are on swivel brackets. One person will climb up the ladder and swing all the antennas folded into the channel boxes upright and insert a pin to keep them securely vertical.

 

[mmckenna]

I'm sorry, I should have been clearer.
The glass mount antenna would be for the GMRS radio.
We will use MURS when we hit interference.

OK, I used a Larsen UHF glass mount antenna for GMRS on my wife's old car. It worked well enough. Not as well as a 1/4 wave mounted on the roof, but it did what I needed it to do.

Trick is keeping it in the clear. On a big RV, it's going to be pretty close up against the window/body, so all bets are off.

Funny thing is, I see some people raving over glass mount
antennas. They claim that they work flawlessly and have
amazing range. I wonder if they love them because of
how easy they are to install. Either way, Larsen or Laird
makes a dual bander for just about $120 +/-. EHam has
a review and all of the hams give it an average of 4.4 / 5
rating.

I put precisely zero stock in any reviews on E-Ham or any of the other amateur radio websites. Most of them are under the impression they are radio "experts" and never make a mistake. Crappy stuff I bought long ago is somehow rated high by a bunch of hams. Not sure what they base the reviews on or what the are comparing against, but take them with a couple of grains of salt.

$120 for a dual band antenna is a heck of a lot of money.

 

[mmckenna]

Our EOC trailer has a 10' mast secured to the ladder on the rear of the trailer. When parked on site, another 10' mast section with the antenna(s) pre-installed is slipped onto the mounted mast, cables connected and we're ready to go. The whole evolution takes less than two minutes.

Probably what I'll end up doing. I need to free up a VHF radio and install it.
I have a solar controller with a 200 watt panel on the roof feeding 2 batteries for house power, as well as the generator. The solar controller has a second output that is currently unused. Might add a third battery for radio.

 

[plughie]

I glued a sheet of steel to the top of my fiberglass RV and used a Tram magmount 2m/70cm antenna.

 

[SpugEddy]

I glued a sheet of steel to the top of my fiberglass RV and used a Tram magmount 2m/70cm antenna.

That was another question of curiosity. What size piece of metal would
I have to glue down for dual band? What size for just UHF?
This is how my brain works: If a 1/4 wave (for uhf) requires 6" ground
plane radials, then I would need to mount a UHF stick antenna on
a piece of metal (ground plane) that is at least 12". I would probably
go to 18" just to be sure. Is my thinking right?

 

[mmckenna]

Needs to be 1/4 wave on the lowest frequency.

So, for an ideally effective 2 meter ground plane, you'd want about 19 1/2 inches in all directions under the antenna, or 39" square with the antenna in the middle.

For UHF, 12" square with the antenna in the middle.

You can go round, if you feel like cutting it out, or have access to precut pieces. Or you can go smaller and live with the drawbacks.

One thing to consider is that any ferrous metal that the mag mount will stick to runs the risk of rusting over time and leaving stains on your RV. Painting it would help.

I've done this on UTV rooftops. It works, but I did drill the hole in the center and do an NMO mount.

If you are going to do the sheet metal approach, you'll need to attach it to the roof. You can screw it in, or you can glue it down and seal the edges really well. You'll still have to get the coaxial cable inside, though. I'd be tempted to just drill the hole for the NMO mount. You can get "thick" mounts that will work with the fiberglass. you can put the ground plane underneath, if you can access it. The ground plane doesn't need to be a solid piece of sheet metal though. You can use wire mesh, or just 3-4 wires going out from the base.
If you are going to need to seal the roof, might as well do it once for the mount and be done with it.

 

[N4GIX]

Probably what I'll end up doing. I need to free up a VHF radio and install it.
I have a solar controller with a 200 watt panel on the roof feeding 2 batteries for house power, as well as the generator. The solar controller has a second output that is currently unused. Might add a third battery for radio.

Here is a picture of "Big Blue" and the mast installed on the right rear.

This year I was very comfortable while operating on Field Day!