nmo roof mount and roof racks

[eachin]

Hello,

I just got my license and want to install a vhf/uhf antennae on the roof of my tacoma with an nmo mount.

I would also kind of like to add a roof rack at some point, maybe sooner rather than later. Preferably a bigger steel one like the Baja racks offering 4runner_iso.jpg 4runner_top.jpg

I understand that the roof rack shouldn't interfere with the antennae or transmissions but it will almost certainly affect the polarity/signal pattern.

Is this an appreciable concern? Do I need to:

a) consider other antennae mounting options?
b) keep the nmo roof mount and ditch the roof rack idea, or just get a smaller lighter duty roof rack (like the OEM option for the tacoma)
c) keep the nmo roof mount, and get a big steel basket roof rack and have awesome transmission quality as well as the option to put stuff on my roof?

Sorry if this has been answered before, I searched, but only came up with one thread that touched on the topic. It seemed to indicate the roof rack would not be a big problem but I would love some confirmation of this.

[Mtn Mike]

That's a great question. I've been considering the same dilemma for a few years. Here a few more thoughts for you:

1) the metal mesh of the roof rack itself will make a good ground plane. Are you planning to mount your NMO to the rack, or to the sheet metal of the roof? I'm thinking the rack is the best option, since it's the highest possible ground plane. As you said, mounting to the sheet metal leaves the possibility of the rack changing your radiation pattern.
2) Assuming you're mounting to the rack, what will you do when you want to take off the rack?
3) What are you carrying on the rack? Bikes, tools, metal gas cans? Any of those things will change your radiation pattern, at least a little bit. Your signal will still get out, but does it negate the advantage of having a roof mount antenna?

Because I couldn't answer 2, and 3, I compromised and mounted my 5/8 wave to my fender :/ I'm interested in hearing how others answer your question. Maybe it is time for me to move my antenna to the roof rack!

[1911]

I run an NMO mount in a small open space at the front of my steel Gobi rack, and there is no practical difference in signal pattern or anything else in use from before I put the Gobi on, even with a little stubby 1/4-wave antenna and with or without the rack loaded:







For your truck, I would probably mount the NMO directly on the rack. If you don't want to give up the space to pack something on the rack right where the antenna is, then mount it off to one side or the other.

[Mtn Mike]

I run an NMO mount in a small open space at the front of my steel Gobi rack, and there is no practical difference in signal pattern or anything else in use from before I put the Gobi on, even with a little stubby 1/4-wave antenna and with or without the rack loaded:
For your truck, I would probably mount the NMO directly on the rack. If you don't want to give up the space to pack something on the rack right where the antenna is, then mount it off to one side or the other.

Thanks for the report. I'm surprised (but encouraged) to hear that you don't notice any reduction in performance with and without the rack. That little 1/4 wave is almost surrounded by the metal cage of the rack. I guess RF waves are more resilient than I thought.

[HenryJ]

I have run a pair of 1/4 wave VHF/UHF on my trucks for quite a few years with no problems.





Both are mounted through the top and use NMO mounts. I also have a small mag-mount 1/4 wave for the APRS behind the rack.

On my old truck they were in the feet:



Similar positions to what I have currently.

[1911]

Thanks for the report. I'm surprised (but encouraged) to hear that you don't notice any reduction in performance with and without the rack. That little 1/4 wave is almost surrounded by the metal cage of the rack. I guess RF waves are more resilient than I thought.

I used to switch-out a Hustler 5/8-wave for the highway, and the performance was better but the difference was small enough that I usually just leave a 1/4-wave on there all the time now. I have a Stico Flexi-whip that I cut for 2m only that does better than the Comet dual-band in my photos (above).

[eachin]

Thanks for the feedback, that's exactly what I wanted to hear. I'd thought about mounting to the rack, but that makes my antennae sit even taller and if I were to mount on the roof and fold at the hinge, then I can still park in my garage, if I add a few inches to that, I'm not so sure..

Nice trucks by the way!

[HillbillyfromAL]

The roof may the best for signal but have you thought about a lip mount for the hood? I've got a UHF mount on the way for my ARB bumper. Mobile solutions are always a compromise of some kind, and a broken antenna is not good for business. Just another idea for you. I got my stuff from the antenna farm they have a decent assortment of accessories and fair prices, and no I'm not affiliated.