Yeah, another Jeep Wrangler Antenna thread with options and questions

[11th]

It would work if it's metal.....
Ideally, you want a 1/4 wave length at your lowest frequency in all directions under the antenna to give it an ideal radiation pattern and allow for the best match.
....
I'd not want a child/family member sitting that close to a transmitting antenna unless it was low power.
There also may be some interaction with the rear part of the roll cage. That may make tuning difficult.
....
If was me, I'd put a dual band antenna that was based off a 1/2 wave design on a bracket off the hood. Put it about halfway between the front edge of the hood and the windshield, like this guy did: Part 3 - Midland MXT400 MicroMobile GMRS Radio & Icom IC-2730A Mobile Ham Radio Install in a Jeep Wrangler – Part 3 | Southeast 4x4 Trails

thanks so much. Good advice on watching out for health harm.
I would say about 95% of the rides I have been where I want the radio I am with a pal or the wife in the front seats and we usually have the back seats removed (they take about a minute to remove from a JK). I do take your point seriously. At this point I have four or five HTs. If I were to mount antenna inside on ferrous steel deck, I will definitely keep that issue in mind should I go from the 5% of the time using a HT to a full power mobile or more than 5% of the time.

On the install you linked. Ironically I was, when initially composing my first post, going to use that as an example of a problematic install. I did not want to call anything out since all installs have serious compromises, but that one is very serious. Instead I i tried to present "pros" and "cons" from what I know of Jeep construction and trail use, and some basic knowledge of electronics, antennas and wave theory, and ask about additional antenna and propagation from experts here, rather than going: "this seems wrong"

So while I give that install an "A" for his comprehensiveness and attention to detail, it seems to me there is also a not seeing the forest for the trees element going on. I see two problems (in addition to the third separate issue of side mount trail damage risk issue):
Firstly his entire presumption on rear mounted being wrong is from examples of people sandwiching, deep down, on average 15 inches down, between a) the tailgate vertical metal and the b) gigantic hunks of metal that comprises the the spare tire wheel, and in some cases the mass of metal that is in a steel belted tire. It is like inserting an antenna into a steel well. Once you do that no matter how good your crimping skills, soldering skills, RF grounding skills are, you are screwed. . This is NOT the case with either the Arizona tailgate or fullmetalfabworks hinge mounts I used as examples #7 and#8 for rear mounting in my first post. One has no metal around anywhere it whatsoever, and one has about 2 5/8" close by on the tailgate lip that could possibly be ameliorated with a spring, as well a a small portion of wheel at a considerably larger distance away.

Secondly he has his antenna 7"-8" below ground plane of hood he is trying to achieve. The loading coil is a) entirely beneath the plane and b) pressed against a vertical potion of hood on one entire side, and a good 3 to 4inches of vertical is also below hoods ground plane. My JK has less of a high side vertical surface, but that TJ has a really tall vertical aspect on the hood. That coil is mounted at the same height as the engine head an way below horizontal aspect of hood.



Again I do not want to be critical, every install has negatives. I prefer us listing out pros and cons. There are (and varying by preference and usage) trail damage potential, cost, efficacy of mount, efficacy of antenna, garage height and other variables where there is no right or wrong answer but rather best practice of considering and of weighing the trade offs and then considering your needs. heck there are even very different rust issues when on starts brushing off paint or making holes. Some people are in rainy and snowy places with lots of salt and some of us are in very dry places with no road salt.

 

[jeepsandradios]

As you have seen there are tons of challenges with all jeeps in general. I have seen hundred of JJK,CJ,JL, JT with various antenna's. Each has a compromise. I guess I'm not sure what you looking for someone on here to tell you. It appears you know what you want to do regardless of people giving ideas and references on how others have done it. I can say with 100% certainty that the fender mount in VHF is fine. I had it on my CJ, TJ, JK and now on the JT. Is it ideal ? nope but it has yet to fail me for what I use it for.

Here is my JT BTW. All band Larsen on the A-Pillar cowl mount. Its hooked to my APX8500 all band radio. It sweeps within specs on VHF/UHF and 800 with my Anritsu




Also here is not best picture but you can see my dual band antenna is on my back rack.

 

[11th]

It would work if it's metal.
Ideally, you want a 1/4 wave length at your lowest frequency in all directions under the antenna to give it an ideal radiation pattern and allow for the best match.
Looks like it would be a bit narrow for VHF use, but for short range work I doubt you'll have an issue.

Yes I think for anyone who has a four door JKU or JLU where the deck is even bigger, and more than one other passenger only rarely in vehicle and who already has a use for a deck security enclosure it is something compelling to consider esp in that I have not seen it mentioned in the zillion wranger+ham posts all over the net.

The two door deck at 39" wide is is fine with the left to right axis in achieving radius and for that matter line of sight. I the foreword back axis is a bit short for desired radius on ham gmrs ranges.

Technical Question: if you are around half an inch short on one aspect of radius; say you need 6.7" which is 13.4" diameter, and say you have 12.9" on that axis, are you better off centering and having 6.45 in both directions; or are you better off making sure one is 6.7 and the other 6.2" ? Ie better to place so one gets 300 degrees or so of over 6.7" or better to split the difference and have front and back 6.5?



Downsides:
1) radiation (highly dependent on amount of usage, power levels)

2) While deck is level with body tub of jeep there would be a small "cone" something like 165 degrees to 195 degrees of interference from small section of spare's steel or alloy wheel poking, and larger maybe 50 degree wide cone if spare is steel belted (my off road M/Ts are kevlar and not steel

3) full 1/4 wave radius on steel deck is easy for JKU/JLU, less so for two door versions

4) unlikely interference from fiberglass hardtop, but possible minor interference from defroster array, possible interference from soft top metal "hoops that support top, especially rearward if soft top is in stowed position

 

[11th]

As you have seen there are tons of challenges with all jeeps in general. I have seen hundred of JJK,CJ,JL, JT with various antenna's. Each has a compromise. I guess I'm not sure what you looking for someone on here to tell you. It appears you know what you want to do regardless of people giving ideas and references on how others have done it.

Frankly none of the threads I have seen on this, and I have seen a lot ,approach all options with a good discussion of pros and cons.
So I do know and stated outright that there are compromises, I just thought it would be good to address as many as possible.

As far as getting recommendations for widely different mounting an antenna options, that is great, but I didn't really ask for recommendations, rather people adding specific pros and cons. Since I know some, but specifically said I do not know all. I do know there are some objectively untrue things floating around, but mainly there is difference in what is traded off.

So it isn't personal as much as general. On a personal level, as I stated I am starting with inexpensive HT, tech license process. My own needs at this point are trail group simplex, and the use of repeaters being practice. So almost all the combinations of mounts and antenna will be fine for that and the practice will help me determine, if, later, I want a mobile unit and professional grade best mount and antenna position/type.

I live in a very high opportunity theft, especially theft from auto, area. $250 a month gets you an outdoor parking space in an ally. I leave my side doors unlocked at night so I don't get a cut open hard top. I keep everything of any even trivial value in the my security enclosure. In the day I often park at worksites in commercial garages. So for both of those, for me, easily removing the vertical is a paramount consideration, whereas for others it might be zero consideration. As I mentioned earlier, for some corrosion would be a major issue and for others not an issue at all. i don't lease my vehicle but for some that prohibits certain cuts. heck I have a manual transmission on my Rubicon, so I dont even have the same firewall options seen on some installs.

So i am not saying: this is wrong and this is right. Nor a I asking: "tell me what antenna to get." I am saying: "here are many of the methods used, some noted on various forums, nowhere as a compendium of all reasonable options for this specific and difficult vehicle type and here are my thoughts on pros and cons: what are your educated thoughts on pros and cons that are not noted or not correct?"

If someone notes a method someone used, and I or someone else note that it seems to have an unnoted downside or tick in the "con" column or violates some principle "dont do this" advice elsewhere, it isn't a conflict, it is just more useful data as part of a inquiry dialectic, where we all agree there are a lot of compromises and filling out some unnoted issues with that option is helpful.

So please do not think I am rejecting advice. I am not at all. In the suggestion we saw from the TJ I just mentioned an assumption I don't see as fully correct ("all tailgate mounts are wrong") as well as what I have read about vertical surfaces and mounting a major portion under a putative grounds plane as having drawbacks. Also my experience these antennas is observations on trails and group rides off road. I have seen fender mounts get screwed from foliage. Just like anyone who has done it long enough has seen the passenger side OEM an/fm antenna torn off of someone jeep including with damage to the body panel I cannot quantify the risk, but rather not it is present. That is why we have this kind of segmenting of: a) jeep priority guys who have hams, b) ham priority guys who have jeeps. And for that matter long trip overlanders. I don't pose it as "vs" but rather as different POV and priority. Group "a" is often going to start as number one priority: get it in the back of the jeep. Group b may well start with equally legitimate for them: "lets get the kit for a half dozen methods/ antenna types, get out the singal analyzier, and test this nine ways form Sunday (with experimenting, calculating, and testing being part of the attraction for the ham oriented people I know)

 

[CaptDan]

NOT RADIO RELATED -

Some off road locations require a "flag" be mounted on the vehicle while operating within their park or facility in order to help with visibility at hill tops.

Some "clubs" have the lead and tail Jeeps display a flag on trail rides.

Other people, like me, would use a flag while on the beach and it's full of Jeeps so Friends coming to meet up with me on the beach could easily find me among all the other Jeeps on the beach.


The second antenna mount makes a great mounting point for the "flag".

 

[mmckenna]

I will definitely keep that issue in mind should I go from the 5% of the time using a HT to a full power mobile or more than 5% of the time.

5 watts from an HT won't be much of an issue. 5 watts from a hand held transceiver held at your face is generally considered 'safe' for occupational exposure. For the 5% of the time you may have someone in the back seat, it's not going to be a big risk. I would have reservations if you were running a 50 watt mobile radio.

I did not want to call anything out since all installs have serious compromises, but that one is very serious.

On a Jeep, it's hard to do an install that is not 'wrong' in some way. If we want to start labeling wrong installs, I could easily point out a number of issues with your rear deck mounting idea. But that won't accomplish anything, and it ignores that there are going to need to be compromises. Since everyone is going to use their Jeep in a different manner, each individual user is going to need to weigh their exact usage scenario against their risks and also their install skills.

Big issue I see is that many want an easy install. That's what often brings us to magnetic mounts and powering radios off cigarette lighter plugs. If you wander through these forums, you'll see hundreds of posts where hobbyists have cut corners on their installs due to lack of skill, lack of knowledge and often, just not interested in doing them correctly. It usually leads to poor performance and/or noise issues. Taking the time to install the antennas correctly and power the radio off a suitable source makes a big difference. When it comes to antenna installs, there's a lot of options, and most have trade offs. Short of a permanent antenna dead center in a properly sized ground plane on top of the vehicle, they are all less than ideal. If you want a perfect antenna install on a jeep, I'd recommend a metal roof. Short of that, they are all compromises.

Firstly his entire presumption on rear mounted being wrong….

Unless an elevated feed antenna is use that is designed around a sleeve dipole, or 1/2 wave design, there's going to be issues with any install back there. Knowing that compromises have to be made when installing on a Jeep, it's more about playing a game of trade-offs, as you've suggested. Some jeep owners understand the compromises involved and are willing to accept them. Doesn't mean they are wrong, they've just balanced their pros and cons based on different variables that what you would.

Secondly he has his antenna 7"-8" below ground plane of hood he is trying to achieve. The loading coil is a) entirely beneath the plane and b) pressed against a vertical potion of hood on one entire side, and a good 3 to 4inches of vertical is also below hoods ground plane. My JK has less of a high side vertical surface, but that TJ has a really tall vertical aspect on the hood. That coil is mounted at the same height as the engine head an way below horizontal aspect of hood.

The coil at the base of the antenna radiates very little energy. Having it down that low isn's ideal, but it's not a show stopper.
As for the radiating element below the hood, unless the amount of metal adjacent to the antenna is 1/4 wavelength or larger, it's not going to play a big role.

On the pro side, it puts the non-flexible part of the antenna down below the hood line. Adding the spring option to the whip addresses some of the tree branch strike risks and allows the antennas to move out of the way. With a solid mount, it's probably one of the better options available.
And a tree branch strike isn't going to mean immediate damage to the antenna. When you start using higher grade antennas, they'll take an amazing amount of abuse before failing. There's a really good reason why those of us in the industry stick to only a few different brands of antennas. It's because we know they are durable and won't fail when needed.

Better location would be dead center of the hood, but I know of only one Jeeper that has actually done that. And it worked very well. Most chicken out and put aesthetics ahead of performance. If you roam around on this site, you'll see that most hobbyists will put form ahead of function. It's pretty rare to find a scanner listener or ham radio operator thats willing to put a permanent mount antenna on the roof of their vehicle. When they do, it's often a reason for celebration.

 

[mrweather]

My wife has a 2016 JK Unlimited and I put the NMO antenna mount on the driver's side fender (like one of the pictures above). I tested Larsen NMO-Q (cut for 2M), NMO150HW, NMO150, NMO2/70, NMO50 and NMO27 antennas using my MFJ analyzer and all gave decent SWR results, though the NMO150 seemed a little more finicky field tuning it.

I'm quite certain the radiation pattern is skewed with the antenna being low and near the corner of the hood but the setup works well enough for me.

 

[mmckenna]

though the NMO150 seemed a little more finicky field tuning it.

That's what I'd expect to see with a higher gain antenna. The low SWR is limited to a narrower slice of the band.

I'm quite certain the radiation pattern is skewed with the antenna being low and near the corner of the hood

Yes, usually the trade off with mounting off to one side of the ground plane. As I mentioned above, steel roof and you'll be all set. Short of that, everything is going to be some amount of compromise from an RF standpoint.

but the setup works well enough for me.

And as always, that's what matters. We can dissect antenna theory all day long, but if you can reliably communicate over the path you need to, that's what matters.

I don't own a jeep, if I did, I would probably mount a 1/2 wave antenna the same way you did.

 

[waynedc]

For a multiband NMO antenna with a rather large diameter base section, I used this on the rear tailgate top hinge bracket. However, I did turn this bracket upside down and that pulled the antenna further away from the spare tire. It came out really nice as long as you remember the antenna when opening your rear hatch - the tailgate fully opened allows the hatch to open and clear the antenna.

HAM GMRS Antenna mount

JL HAM Antenna Bracket

www.cooltechllc.com

 

[CCHLLM]

My experience over the years has been that the roll cage does have a large negative effect due to the proximity of the cage elements in the rear area. The horizontal propagation pattern of the antenna being somewhat centered in the same horizontal plane as the roll cage structure results in the perfect proximities to distort and attenuate the propagation in the desired directions. We saw some installations with 2:1 SWR indicated, but the impedances were at least 20 to 30+ ohms either side of 50. That means part of the radiation at that point is probably coming off the shield portion of the feedline. That may or may not cause the factory installed smoke in the final amps to escape, but according to the RF field strength meters set up around it, the proximity influence of the cage makes the radiation pattern a really interesting and distorted critter.

 

[mrweather]

I don't own a jeep, if I did, I would probably mount a 1/2 wave antenna the same way you did.

Interestingly enough, the NMO150HW antenna seemed to be the best overall VHF performer for me on the Wrangler.

 

[mmckenna]

That would also make sense. The half wave antennas are ground independent, and should give you a good match in that application.
I'm using a Laird half wave VHF antenna mounted on the roll cage of a UTV and I'm happy with the performance. It's set off to one side, so it's got a less than ideal ground under it. It's on top of the cage with the coil slightly lower than the bars, so it is up as high as I can get it. I've hit tree branches going 30-40mph on trails and the end of the whip has a kink in it from that. So far the spring at the base has absorbed everything I've thrown at it.
I even went as far as running slowly through a culvert under railroad tracks where the antenna was fully bent over 90º at the spring, and it bounced right back with no issues.

 

[slowmover]

Stopped off at DTB Radio (Carlisle, PA) a couple of weeks back to have a CB repaired and noticed his JK had a mount I hadn’t seen. I liked it for simplicity and coax routing:

Refer to earliest pics in thread for open screws (not hidden) on A-pillar / Windshield join

Mount is simply a 45-degree piece of stamped SS with washer that goes underneath a screw. ($10)

4.5’-5’ Fiberglas CB top-load. Coax routes easily to dash.

Not making any kind of claim +/-. Shop owner is an Amateur licensee and presumably knows something (been in business 20+ years).

Given the difficulties of the JK, it’s a fast way to get on-air.
An FYI post.

.

 

[prcguy]

Nice JT! I have one on order and its in the shipping stage right now, can't wait to get it. I'll be crawling all over it to mount a couple of antennas and am looking at removing the plastic cowl piece that is under your tri-band antenna bracket to see if an NMO L bracket can screw into the side of the long cowl piece and stick up through the gap between the straight and curved cowl pieces. Is the long straight cowl piece on a JT metal or plastic?

I have several long antennas to play with for occasional use and think I have a solution for that. The first is a huge and ugly Hi-Q HF screwdriver with long 5" dia coil. Then I sometimes use a 9ft long military Shakespeare 30-512MHz whip and I like the ability to test NMO and 3/8-24 thread whips. I'm looking a mounting spot at the top bed rail up against the cab where there is a flat spot on each side behind right behind the cab.

I have a universal military triangle mount I plan on putting right below the bed rail on the inside and that will have adapter plates for the big HF antenna and NMO and 3/8-24 that I can swap around. It should space any antenna out a few inches to clear the bed rail overhang. The mount can also house things like the HF matching transformer that is needed for some whips with a 12.5 and 25 ohm tap under a removable cover on the mount.

I already painted the green military mount black to match the bed liner and made 1/4" thick adapter plates with various mounts with one more to go for the big HF quick disconnect mount. I had one of these mounts on my last truck and it was very handy to interface with all the military antennas I have.

As you have seen there are tons of challenges with all jeeps in general. I have seen hundred of JJK,CJ,JL, JT with various antenna's. Each has a compromise. I guess I'm not sure what you looking for someone on here to tell you. It appears you know what you want to do regardless of people giving ideas and references on how others have done it. I can say with 100% certainty that the fender mount in VHF is fine. I had it on my CJ, TJ, JK and now on the JT. Is it ideal ? nope but it has yet to fail me for what I use it for.

Here is my JT BTW. All band Larsen on the A-Pillar cowl mount. Its hooked to my APX8500 all band radio. It sweeps within specs on VHF/UHF and 800 with my Anritsu


View attachment 97800

Also here is not best picture but you can see my dual band antenna is on my back rack.

View attachment 97801

 

[jeepsandradios]

So the cowls parts are definitely plastic but to be honest don't remember on the center piece. I can check today for you. I did not use the factory bed rails and made my own out of unistrut and had them powder coated. The unistrut (and there are people selling rails like this) is flush with the bed side so putting my back rack on was a breeze.

I actually went with the cowl mount for the antenna and wife said it looked funny with one on left and none on right so installed the other and a cheap set of fog lights. For the most part I've had no issues on my 8500, but its mostly VHF repeater, UHF trunking or smart connect. I did carry a half wave VHF under the seat that is tuned on our SAR channels if I run into issues with the all band. The half wave VHF on the back rack worked pretty decent on our trip this winter to FL and back. I still run it on the rack at home. I do carry the original 1/4 wave 2m/440 that was on the pic above under the seat. Needed it in a few parking garages over vacation.

Inside has been a challenge. I have the 8500 O3 head on a ball mount on the grab bar along with my CB. Problem is it keeps getting loose. Need to come up with better mount. Switched to mm and better but still needs work. the FTM400 is on a grab bar mount also. I did just install the new bulletpoint mount on the dash. Its nice. I have my Garmin Overlander mount, my Inreach mount and my camera all on it. Need to order an arm for the phone.

Bulletpoint Mounting Solutions for Jeep, RAM Truck & Ford F-150

Rock Solid & Reliable Phone Mount Dash Solutions for Jeep Wrangler JK JKU JL JLU and JT Gladiator, RAM Truck 1500, 2500, 3500 and Ford F150.

www.bulletpointmountingsolutions.com

I like those military mounts.

 

[jeepsandradios]

"Is the long straight cowl piece on a JT metal or plastic?"

Plastic. Entire front cowl is plastic parts.

 

[prcguy]

Rat Bastids! I don't like the idea of an antenna hanging out in the breeze off the side of the cowl so I'm going to look at the thickness and integrity of the plastic center cowl piece and see if its strong enough to screw in an NMO bracket like this: Lot of 2 TRAM 1255 B NMO L BRACKET MOUNT BLACK STAINLESS STEEL 713331005964 | eBay

If its strong enough I will consider one of these screwed into each side of the long center cowl piece then I'll line the underside of the plastic parts with wide copper or aluminum tape and ground that to the metal underneath for the ground plane. That would leave the NMO mount low on the cowl with the coax exit point almost touching the top of the cowl. I really want the NMO mounts to be on a flat part of the cowl on both sides with the brackets hanging over the smaller removable cowl parts on either side. The only problem I see and want to avoid is the cowl mounted antennas being right in my view out the front window. I'm hoping they will be off to the side far enough to be a non issue.

I'm thinking the military mount might go on the upper bed rail area right behind and centered with the rear window and butted up against the bottom of the trail rail system. I purchased another round aluminum plate and will be installing a Hi-Q antenna AQD mount on that, which is a huge bayonet quick disconnect for the largest HF screwdriver antennas. I have a 5" coil 160 through 10m Hi-Q screwdriver and the military mount will then take my 30-512MHz 9ft military Shakespeare whip or my huge 7ft 2m gain antenna or CB whips or scanner antennas, you name it.

I plan on installing a tall bed rack system that will extend above the cab to carry two kayaks and other stuff and the military mount centered in the rear window should allow the antennas to stick up between the kayaks. My new truck should be here end of next week at at this point its all just ideas since I don't have anything to verify all these ideas.

"Is the long straight cowl piece on a JT metal or plastic?"

Plastic. Entire front cowl is plastic parts.

 

[prcguy]

Slight change of plans after I picked up my new Jeep Mojave and looked over antenna options. I'm not comfortable screwing in the NMO angle brackets mentioned in the last post into the sides of the plastic cowl pieces. I found the back edge of the steel hood should take a clamp on trunk lid mount just fine so I ordered two Laird trunk lid mounts in black like these. TMB8U - Trunk Lid Mount, No Connector - 17' RG58U - Laird Technologies 56237 729198562373 | eBay I'll also line the underside of the top and side plastic cowl pieces with wide aluminum tape then bond that and the metal body to the hood with a short wide piece of flat braid near each hood hinge.

The picture below shows the rough location of the antenna and the hood gap is plenty wide for the mount and coax to pass when opening the hood. The only slight drawback will be the whip visible from the drivers location, but what's more important, radios that work good or your view? I mean, who really needs to look out the front window when driving and talking on the radio?

Rat Bastids! I don't like the idea of an antenna hanging out in the breeze off the side of the cowl so I'm going to look at the thickness and integrity of the plastic center cowl piece and see if its strong enough to screw in an NMO bracket like this: Lot of 2 TRAM 1255 B NMO L BRACKET MOUNT BLACK STAINLESS STEEL 713331005964 | eBay

If its strong enough I will consider one of these screwed into each side of the long center cowl piece then I'll line the underside of the plastic parts with wide copper or aluminum tape and ground that to the metal underneath for the ground plane. That would leave the NMO mount low on the cowl with the coax exit point almost touching the top of the cowl. I really want the NMO mounts to be on a flat part of the cowl on both sides with the brackets hanging over the smaller removable cowl parts on either side. The only problem I see and want to avoid is the cowl mounted antennas being right in my view out the front window. I'm hoping they will be off to the side far enough to be a non issue.

I'm thinking the military mount might go on the upper bed rail area right behind and centered with the rear window and butted up against the bottom of the trail rail system. I purchased another round aluminum plate and will be installing a Hi-Q antenna AQD mount on that, which is a huge bayonet quick disconnect for the largest HF screwdriver antennas. I have a 5" coil 160 through 10m Hi-Q screwdriver and the military mount will then take my 30-512MHz 9ft military Shakespeare whip or my huge 7ft 2m gain antenna or CB whips or scanner antennas, you name it.

I plan on installing a tall bed rack system that will extend above the cab to carry two kayaks and other stuff and the military mount centered in the rear window should allow the antennas to stick up between the kayaks. My new truck should be here end of next week at at this point its all just ideas since I don't have anything to verify all these ideas.

 

[jwt873]

That's a good looking mount.. But won't the antenna contact the windshield when you lift the hood ??

 

[prcguy]

The whip might lay against the hood when its up but any antenna I use there will be thin and flexible. I'm installing gas struts on the hood which will not only raise the hood but limit how far back it goes, so that will be less of a problem.

That's a good looking mount.. But won't the antenna contact the windshield when you lift the hood ??