42G Antenna

I just bought a 42G antenna to install on my 24’ shuttle bus. It has a painted aluminum roof. Where is the best location to install? Maybe in the center of the roof? Does it really matter?

Given the frequencies involved it does not make a lot of difference so long as the antenna is not “shaded” by roof-top obstructions such as HVAC units. Aesthetically, we’d usually try to mount such an antenna along the center-line of the roof positioning the antenna for the shortest run of transmission line possible. The latter consideration is typically more important than the precise location of the antenna.

You chose a good antenna.


What about mounting on the fiberglass “bubble roof” over the front area?42338-c-7-f-ce-1-b-65-dc-f-5518-b-4-e-481-f-419-d.jpg

IMO: Yes, it does.

Even antennas that don’t “need” a ground plane will be affected by the presence of one. Here’s a graph from Peplink showing the difference in the 42G’s performance with and without a ground plane:

(Taken from Choosing The Right Antenna )

What that graph implies is that if you mount the antenna, say, near the front of the bus, the antenna’s radiation pattern will be somewhat pulled to the rear of the bus. Being as antenna gain is a zero-sum game (i.e.: gain in one direction means loss in another), that means performance to the front will suffer.

Now, to what degree? Dunno. May or may not be significant. But I’m pretty sure I was recently burned in part by ground plane effect on an install in a fixed remote location.

So, if you can mount that 42G smack-dab in the center of the roof, and the roof is as clear and flat as it appears to be in the photo you supplied, that’s where I’d recommend you put it.

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Thanks. That is kinda what I was thinking but wasn’t sure.
I can easily mount the antenna in the center of the roof area and can mount the router/modem underneath to the ceiling so I don’t have to add any cable to reach.

Sounds good. Just make sure that, where you mount the modem, it has plenty of free air surrounding it. If this MAX BR1 Pro 5G I have sitting here is any guide: These modems tend to run a bit warm. Heat is tied for First Place as Semiconductor Enemy #1 (along with static discharge).

@David_Shelton: Not sure what area you are referring to looking at the photo. If it’s the area directly over the driver’s position I would not do that for two reasons: (1) the gain is slightly higher when mounted on metal surface and (2) the vehicle behind would attenuate the signal.

The amount of ground plane which is beneficial is a function of frequency. We have a VHF-UHF antenna test range and have around 40 years of experience in positioning antennas on vehicles and measuring the results with lab-grade instrumentation. You’ve got the right idea. Mount the router in a location where transmission lines can be kept short. In the 600MHz-2.5GHz range that’s more important than a few feet forward or back on the metal roof.


Thanks for all of the replies. I would think the relatively flat aluminum Roof with no obstructions should work well. The antenna will have to be mounted a couple of inches off center due to a stiffener rib running down the center but I can’t see how that will hurt anything.

I would guess that there is no real front or rear when it comes to the mounting position of one of these antennas?

Not an issue at all being a few inches off center. As I indicated, you can move that antenna most anywhere on that roof and the pattern will only be minimally affected. (That would not be true at much lower frequencies but that’s not what we’re dealing with here.)

And no, there is no “front or rear” with this sort of antenna – it’s omni-directional. Just make certain the “Pepwave” logo is nicely visible to passers-by! ;<)

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This is working. As far as the WIFI antenna portion. This connects to my router? Is it to receive or transmit WIFI signals?

The antenna does both.

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