Antenna mounting options

[Kyle Kelso]

Hey everyone

I'm a relative noob with radio's and I'm trying to figure out the best locations to mount the 3 antennas I will have to install. I have a 2004 Suburban and I have a cell booster, cb radio and 2m ham radio I want to install in this truck. I've had the cell booster mounted with vehicle specific fender mounts on the last couple trucks and the cb just had a magnitic mount on the roof which has ended up in the garbage and needs to be replaced (it got damaged but I hated having to stick it back on after branches would knock it over.) I am installing a large roof top tent which will cover most of the roof and have a sunroof up front so a roof mount seems like it would be out of the question. I have found a couple different fender mounts that might work together, Comet SUANTPF https://www.radioworld.ca/comet-suantpf and the Walcott Radio GM2L https://www.walcottradio.com/gm2l-f...-silverado-avalanche-and-suburban-p-1184.html and possibly the Comet AVANTPF https://www.radioworld.ca/comet-avantpf . If those all fit together on my vehicle then my only concern would be if 2m, cb and cell booster antennas can operate that close to each other or is a certain minimum spacing required? I will likely be installing limb risers (cables from hood to roof to deflect branches) but would it be best to install springs at the base of the cb and 2m to be safe?

If I need to utilize different mounts what would be the best route to go? I've seen mounts that clamp on to the ractory roof rails such as https://www.radioworld.ca/dia-k515snmo but I don't think I'll have any of the factory rails exposed with my RTT installed. I will however have 4 Thule square cross bars that will have some available space but I haven't seen any mounts for such. Could I just drill out and bolt on some stainless steel or is there more to it than that? I'm not sure I want a 3-5' fiberglass antenna bolted to the roof rack of a truck that will be driven through the bush but I guess with a 12" tall RTT already on the rack a stainless steel antenna should be fine with a good spring at the mount, or would a fold over antenna maybe be a good option?

The only other option I can think of would be a tall fiberglass antenna mounted on the top of the corner of the rear bumper.

What are your recommendations? I'm away for a couple weeks and hoping to order stuff so I can install it when I get home otherwise I would just drive down to a local shop and get their advice...

Thanks for your input!

 

[prerunner1982]

I think any of those fender mounts you linked will work fine. If the roof is taken the front fenders would be my next option. If you have a factory am/fm radio antenna on the passenger fender I would put the 2m antenna on the driver side and the CB antenna on the passenger side. However, 1/4 wave 2m antennas are short enough that it could be mounted on the roof rack and survive though the RTT may block most of the antenna, but probably no worse than having the antenna down on the fender. A 5/8 wave whip is plenty flexible as well and would likely do ok on the roof rack, it is long enough that the RTT would cause little issue with blocking the signal.

 

[Kyle Kelso]

I ordered the mount from Walcott Radio with a 3' Firestik and a heavy spring for my cb. I'm going to see if I can find one of those Comet fender mounts locally for my cell booster and probably hold off a little while on the 2m radio.

 

[Frdmskr]

Drilling a hole and mounting an NMO on the roof is always the best. Any bumper is always the worst. The more vehicle under your antenna the better. Then there is reality.

Now, given many folks use RTTs, etc on their roof it may not be available. I have a cheap MFJ clamp mount on the hood of my 3rd gen 4runner for my Larsen NMO270. Larsen makes a CB antenna that can use the same mount. If you prefer a Firestick or a long 108" whip, then put a good ball mount on the rear quarter panel and wire it up right. For the cell booster, I am unfamiliar with them but the higher the better. Find a place on the roof or engine hood and mount it there. Holes will be drilled...someday...if I say it enough it will happen. There are a few things I need to address first....like what I am doing with the truck. FWIW, I had 3 NMO antennas drilled an mounted on the roof of my last truck (Ford Escape) and loved them.

Do not use magmounts, drill a hole. Always better and much higher survivability.

 

[Kyle Kelso]

Parts were waiting on my doorstep when I got home

 

[sonoronos]

Drilling a hole and mounting an NMO on the roof is always the best. Any bumper is always the worst.

Nope. Well, nope with some caveats Sometimes this is true. Sometimes not. It really depends on the antenna and the transmitted frequency. A good NGP or Base Load antenna can obviate the need for roof mounting at HF and at 2m/70cm or less, the need for a ground plane is waived by simply having grounded sheet metal around the antenna. I run 1.35 SWR on a Laird CB27S and a minimum 1.3 SWR 2m ( 1.7 SWR at full power) on a NMO 2/70 - both running on opposite corners on the winch bumper of my rig. These were measured with an impedance analyzer on-truck, not an SWR meter.

When operating with a go-box with the NMO 2/70 with no ground plane and just flesh, blood, and a picnic table around the antenna, it has an SWR of about 2.8 to 3, which is pretty bad. But the moment I mount the NMO 2/70 to an 8" diameter circular pie tin, its SWR drops to 1.5 or less. I've also tested the antenna mounted to a 4' square sheet of aluminum and the SWR doesn't go below 1.3.

So is roof mounting the best for SWR? Nope. It does get you more height on the antenna, which is universally acknowledged as better. But you know what gets better height than drilling a hole in a roof and putting the antenna mount in the hole, compromising the water resistance of your vehicle and ruining its resale value? Mounting your antenna on a mast, or a rack. Even more height, and therefore superior to roof mount.

Is bumper mounting the antenna the worst? Nope. The worst placement would probably be mounted down low on something plastic and totally ground-isolated from the rest of the truck, or where it's blocked by sheets of grounded metal, like against the body of a trailer or something. But even then, it's going to have directional propagation in the opposite direction.

 

[Frdmskr]

SWR, Impedance are not the only measures of antenna performance. Looking at take off angles, radiation lobes and such are bigger considerations. SWR measures how efficient the circuit is getting energy from the rig to the airwaves. The pattern of lobes is key to performance.

If the lobes are blocked then you have attenuation in that direction. If you have a reflector or director properly spaced you can cause directivity.

Numerous RF studies have shown that the best place for an antenna is the roof. Engineers don't grow trees so common sense says you might need to have a compromise on placement due to obstacles and to ensure a happy marriage.

I have my antenna on my engine hood about a 1/2 wave from the A pillar because I am cursed by parking garages. It's not ideal but it works. Maybe someday I'll move to a more civilized place like the Rockies lol


Sent from my iPhone using Tapatalk

 

[BigSwede]

Drilling a hole and mounting an NMO on the roof is always the best.

Until it gets torn off by a tree branch.

 

[old .45]

Until it gets torn off by a tree branch.

I have a 27 mhz stainless whip (it is a commercial antenna and mount) about 3' high or so mounted on my left front fender of my F150, no issues at all it shrugs off tree branches no problem and is tuned perfectly.

 

[sonoronos]

I have a 27 mhz stainless whip (it is a commercial antenna and mount) about 3' high or so mounted on my left front fender of my F150, no issues at all it shrugs off tree branches no problem and is tuned perfectly.

Yeah, there really should be a snopes article on this whole "drill a 3/8" or 3/4" hole in your expensive roof for best performance" thing. I don't know where this started, but it's infected a lot of minds and really doesn't make sense even from the point of view of physics.

 

[SteveG]

For any antenna, the best mounting point is in the center of the roof. If your roof is long enough, space them evenly and put them all up there. My Explorer has 3 antennas spread accross the roof. All of them work great... good ground plane, no obstructions. Nothing but clear air.

 

[BigSwede]

For any antenna, the best mounting point is in the center of the roof. If your roof is long enough, space them evenly and put them all up there. My Explorer has 3 antennas spread accross the roof. All of them work great... good ground plane, no obstructions. Nothing but clear air.

You've obviously never driven down an ATV trail in dense woods...your antennas wouldn't last 30 seconds there.