Looking for antennae bumper mount hardware suggestions

[rayra]

For various reasons of aesthetics, desired pattern of use, my expected range requirements and that my vehicle is an urban daily driver, I wish to have my CB and 2M HAM radio antennae readily removable and stored inside the vehicle, leaving the mount and antenna cabling in place. I'm choosing to mount each antenna at the outer corners of the rear bumper. I would like the mounts to be as flush with the top of the bumper as possible, likely with a rubber or plastic cap covering the threaded hole for the antenna. I intend to drill the bumper and make any modifications necessary to the bumper bracket / inner structures needed to attach the antenna mounts. The antenna will be in the ~48" size range. Looking at Firesticks, but open to other suggestions. Don't reall want a big ball or spring mount.

I don't seem to know the right keywords to use in my search, as most of the mounts I'm finding are meant to simple go thru a hole as with a roof mount, clamping onto the plate metal via nuts, and protruding as much above the sheet as below it.

Any suggestions that come close to these mount criteria?


eta - something akin to this configuration, but preerably with very little above the bumper top.

 

[rayra]

a bit of my radio console design, as further info on where I'm coming from. I'm replacing the factory center console in my Suburban with a custom build, still in progress. It will house both a CB and HAM radio and their handsets in a console that's upholstered to match the interior of the vehicle. The radios will be concealed by a sliding door akin to a rolltop desk or 'kitchen appliance garage'. It will slide down into the console to reveal the radios. I'll likely fashion the door out of strips of ebony. I'm afflicted with a black vehicle with gray interior.

I'm going to skeletonize the radio rack / interior chassis to provide as much ventilation as possible and likely incorporate a near-silet 12VDC computer fan to blow air onto the radios. The side exterior panels will snap on, allowing them to be removed for access to the radios or antenna connections. I'm replacing the defunct OnStar panel above them on the dash with my switch panel for various things, I'll add a separate power switch there controlling power to both these radios and the fan. Might get fancy and try to rig a solenoid to the sliding door, open the door, power on, close the door, power off.

I'm using MDF, it's easy to work with and shape, makes clean rounded edges for upholstering, rather than splintering plywood.

 

[matthewp]

For the rubber caps, Napa Auto has rubber caps that fit perfectly over the mount base on my antenna.

 

[Frdmskr]

You will only get close to flush with an NMO mount. All others will protrude a couple inches. You'd drill a hole in a metal bumper and go from there. Must be metal or it won't work right.

An NMO mount will allow for a cheap cap ($5?) on top that goes up about 1".

Now for an antenna you can do 2 things. They have NMO to PL259 /SO 239 adapters. I cannot vouch for their mechanical strength so it could get interesting. With that you can use the fire stick. Leaving as a plain NMO you can put on any number of 2m/440 antennas.


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[rayra]

ah, thank you both. NMO is nice and low. Not flush, but that's ok. I want(ed) something as unnoticeable as possible, so idle hands / minds are not drawn to mess with it. Presumably I'd leave the NMO to 3/8-24 adapter, spring etc fixed to the antenna, and just spin the hole thing onto the NMO when I'm ready to use the radio.

https://breedlovemounts.com/NMO_Mounts.php

The other possibility that occurred to me today was to use a standard stud mount, mounted to an L-bracket attached to the bumper's internal vertical brackets, and just cut a thru-hole in the bumper surface. Positioning things such that the stud mount only pops up a 1/4" or so. Could put a simple nylon plug / cap in it when not in use and it would be pretty innocuous. But when the time comes there's enough sticking up to get a wrench on for tightening the antenna.

I can determine the size of the hole needed in the bumper to clear the stud mount, plus room for a wire grommet to cover the cut edge of the bumper metal and use hole saw 1/2" wider to make a bigger cut thru the rubber traction pad on top of the bumper, so it is relieved away from the hole, for cosmetics. Do that wider relief cut either way, recessed stud or NMO surface mount.

 

[PapaJeep]

The nmo mount leaves very little sticking above the mounting surface. Some thing like a 1/4" or so. It is also designed to be easily removed and replaced just like you intend to do. It is easy to cover with a protective cap.

Paint the cap to match your bumper. That should be about as low profile, easily removable, and weather tight, and inconspicuous as you are going to find.


Btw: nice work on the center console/ cabinet. What do you plan to cover it with?

 

[AlbanyTom]

I used to have a '78 Blazer. Built like a tank. I still miss that...still haven't driven anything that was better in the snow on the highway.

You probably don't want to hear this, but this is what I would tell a friend if they were planning what you're planning: You've spent a lot of time planning out the radios. It's going to be a great setup, with the console and cooling and all. But, and I mean this in all honestly, you probably couldn't pick a worse location for the antennas. I mean, mounting underneath *might* be worse, but I'm not positive. I say this because the body of the giant truck is going to block your signal close to 100% on 2m on the directions toward the truck, probably close to as bad on CB, and the proximity to the steel body for both is going to hurt performance. Not sure, but as you drive the truck it's probably going to change the tuning of both as well.

Again, I know you might have planned this all out, but I would suggest instead, so that your antennas match the work you've put in the rest, put 2 nmo's on the roof. In line, one in front of the other. For 2m, put a highly flexible whip on it, you can drive into a 7' parking garage, as long as you're not lifted too much, and not hurt anything. For CB, put a stubby rubber duck on for daily driving, switch it to a base loaded whip when you don't have to go into garages. Then you have radios that work all the time.

Oh, and a couple of NMO's on the roof of an SUV don't look weird, or unsightly. They look professional.

 

[rayra]

I get all that, considered all that. I understand that bumper mounting will be limiting and I accept those limits as I understand them to be. My terrain will be mountains near repeater and SoCal high desert. ranges will be short. Convoy / caravan ops. Using FRS radios now, anything will be an improvement. If I need longer ranges I've got bigger problems.

I am considering a 3rd antenna lead and a roof rack mount, which could be swapped (and tuned) as needed between the radios. But my anticipated use is casual and close range. And I've got no problem re-orienting a vehicle to have a clear line in the direction I want. When I'm truly 'expeditionary', I can go high with the antenna.


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The console will likely be covered in the finest pleather over a thin foam. Vehicle interior is medium gray leather.

 

[4x4junkie]

I'm with AlbanyTom. If it does provide any improvement over your little FRS radios, it certainly won't be by much.

I've said it elsewhere... There are numerous options available for quick removal of antennas or having them be able to deflect out of the way should you encounter a low-clearance situation (antenna springs, quick-release (bayonet-style) antenna mounts, fold-over mounts, and so forth). Whether you think you need the range or not, why purposely limit yourself? There's no way to know what situation every outing is going to present.... Should you for example be partway into a trail and someone in the group realizes he/she forgot something and has to turn back a couple miles to go to a store in a nearby town, etc., would you not want the best chance of being able to maintain comms with that person? (especially 5 minutes after they left you come to realize your cooler needs more ice too)

Just my 2¢... only because I know how frustrating it is when I can't hear someone (or they can't hear me) when something important is at hand.