Mobile Antenna

[tweiss3]

I'm a bit new to radio. I drive a lot, traveling with my company car. I've been using a CB with a magnetic LilWilly whip antenna. I also have to have access to the weather (outside of my phone) and always thought radio was cool, so I have a BF-F8HP that I have been using for analog scanning, which is a benefit because I get the county skywarn channels for weather alerts as well.

 

Anyways, I decided to grab a GMRS-V1 to be legal since I filed for my GMRS license. I have noticed, half the time if there is GMRS chatter, it is only picked up on the F8HP and not the GMSR-V1. Since I'm in a company vehicle, drilling is not an option. Should I go with a magnetic mounted antenna or just get a better 8" whip that is 1/4 wave. If i went magnetic, i'd get a triband that would have me ready for either a true 50W mobile rig or digital mobile scanner (P25 capable). If it helps, I currently clip the radio to my sun visor while scanning.

 

If magnetic, will there be a grounding plane required (similar to CB)? How large? Will it interfere with the CB?

 

If upgraded whip, any affordable optiosn other than Nagoya NA701C? 

 

I'm currently studying for my amateur technician test, but I still have so much theory I don't understand yet as far as antennas.

 

Thanks,

 

[axorlov]

Magnetic antenna on the roof will always be better than HT antenna inside the car. Ground plane required for most mobile verticals (there are exceptions, like 1/2 wave antennas), however, the roof of your car/truck is a ground plane. Magnetic mount couples with it capacitevly. I assume, the roof is steel, cause you're talking about magnetic mount. Good ground plane is anything more than 1/4 wave in all directions, and if it is bigger than 1 wavelength, it is close to ideal.

 

P25 scanner would be in 400-800MHz range? I would not sweat about tri-band, because your 460MHz antenna will work beautifully as a receiving-only antenna for higher frequencies. If you plan to scan in 100-800MHz then dual-band will suffice.

[tweiss3]

P25 scanner I hope to get at some point is an SDS100/200. I'd like to pick up the 140's, since that's what the county skywarn is on.

 

When looking for for an antenna, is the ideal 1/4 wave? For my conditions atelast? Right now I drive an equinox, but will be going to a silverado in about a year (less roof area).

 

I'm looking at the UT-308UV due to the price point (a bit hard on money right now). Any other reasonable priced brands I should be looking at? Thanks.

[Lscott]

A 1/4 wave whip maybe your best bet for the moment, and not just for technical reasons. It seems you want to put the antenna on the roof of a pickup truck at some point. A 1/4 wave antenna will only be around 6 to 8 inches tall. You'll soon discover that's an asset when you find it necessary to go through a "drive through" window at a bank, fast food joint, parking garage all with a low overhead limit. The truck, or most SUV's, roof is already taller that a typical car decreasing your head room. A higher gain antenna is going to be taller. I have a high gain dual band on my Jeep that's about 60 inches tall. I have to think all the time about where I need to drive to avoid damaging it. Sometimes I have to get out and unscrew the thing from the roof rack mount.

 

One other point a 1/4 whip, when tuned right, has a very wide bandwidth. I've built a few for inside and temporary use out of a male BNC PCB socket and stiff bus wire. I can get the SWR down to under 1.5:1 from 430 MHz to 470 MHz with 3 feet of small gauge coax measured using an AA-1000 antenna analyzer. That covers all of the usable Ham 70 cm band and all of the FRS/GMRS channels. You'll find that advantageous when you get your Ham license.

[tweiss3]

Lscott, thats along the lines I was thinking as well (i do occasionally have to send a young engineer with my truck to drop things off).

 

What brands should I stay away from?

 

I'm currently looking at Nagoya and Larsen, though the Larsen are considerable more money.

[Lscott]

Most antennas I see are gain type and the height gets up there.

 

The link below has a selection of 1/4 wave types.

 

https://www.pctel.com/wp-content/uploads/2018/11/Product-Datasheet-25.pdf (catalog page)

 

https://www.pctel.com/ (Main site)

 

The above is a suggestion for reference.

 

The model PCTCN4347 I think will work and about 6.2 inches tall. This is pre-tuned for 430 MHz to 470 MHz. You will also have to get the magnet mount which is an extra cost. It looks like they require an NMO type mount. I don't known what the cost is for the antenna and mount. You can contact the company.

 

This company seems to carry the antenna series but I don't see anything mentioned about selling a pre-tuned one. I think you have to cut the element to length for the frequency you need. The manufacture may have that data or the antenna comes with a chart you reference for the recommended length. Again I would contact them for details.

 

https://www.theantennafarm.com/catalog/pctel-maxrad-pctcnmft-5913

[JJM]

Drill it!

 

 

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[Lscott]

Drill it!

 

 

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Yea, some say you're not a real radio guy until you drill holes in your ride to mount the antennas. Can't do that with company stuff, rentals or lease.

[Jones]

One mag-mount solution that I have had good luck with (for not very much money) is the Tram 1235 NMO mag-mount with the Tram 1126-B 1/4 wave antenna.

 

You should be able to pick up a set for $25-35 on eBay or Amazon.  I'd look on Amazon, since if you don't like it, you can return it.

[JJM]

Yea, some say you're not a real radio guy until you drill holes in your ride to mount the antennas. Can't do that with company stuff, rentals or lease.

No one has ever had a problem doing it on a lease. Most people are oblivious.

 

As for company: get permission. Rentals: yeah not worth the effort.

 

 

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[PRadio]

 Rentals: yeah not worth the effort.

 

 

 

I disagree. On a rental it is much, much easier. Simply drill through the roof and headliner, and run the wire through. Easy peasy. 

[tweiss3]

Yea, not drilling a company vehicle, especially one we are getting rid of in less than a year. Also, the sunroof makes the area to drill microscopic.

 

(I'm using Flickr for photos, if they are not working, let me know please)

 

Anyways, I got Tram 1267 mount (5.5" base, my screw up, didn't read the size) and a Tram 1126B quarter wave antenna. My problem generated by my screw up, the corrugation pattern on the roof sheet metal makes it so I have to set the mount forward of the corrugations. See the photo:

GMRS Antenna by tweiss3, on Flickr

 

Question #1) Am I correct in the fact that its too close to the sun roof, so it won't transmit in the forward direction well?

 

Secondly, I want to set it to the back so I can tuck the wire nicely, like I have my CB antenna. Will it cause any issues if I mirror it from the CB along the back? Won't overload the car radio? S the photo below.

 

Roof Antennas by tweiss3, on Flickr

 

This is my GMSR-V1 for now, but if my bid goes well, it will be a 45W mobile mounted in the back.

 

Question #2) If that were to happen, will it cause problems if I loop the excess cable on itself to tuck it away?

 

Thirdly, I bought a NanoVNA due to its wide availability of use. I tested the Tram antenna as installed above in the car. I'm pretty impressed. SWR 1.3 is pretty good (-16db return loss).

 

SWR@467.6 by tweiss3, on Flickr

SWR@462.2 by tweiss3, on Flickr

 

Question #3) I'm just starting to understand some of this theory stuff while simultaenously studying form my Amateur Technician, so I'm on data overload right now. Is there anything else I should test on that antenna? Is there a way to verify my little 2W radio is getting out and not loosing too much through the cable, or is that what the SWR/Return Loss is identifying. 

 

Thanks for all the help so far. This place is a mountain of information and help.

[tweiss3]

I think my questions got hidden by photos, so I'm breaking them out here.

 

Question #1) Am I correct in the fact that its too close to the sun roof, based on the photo above, so it won't transmit in the forward direction well?

 

Question #2) If I were to install a radio in the back, will it cause problems if I loop the excess cable on itself to tuck it away?

 

Question #3) I'm just starting to understand some of this theory stuff while simultaneously studying form my Amateur Technician, so I'm on data overload right now. Is there anything else I should test on that antenna? Is there a way to verify my little 2W radio is getting out and not loosing too much through the cable, or is that what the SWR/Return Loss is identifying. 

[marcspaz]

1.) You should have about 7 to 8 inches of reflective surface in all directions.... about 14 to 16 inches in diameter. So, I would move it back more.

 

2.) Yes and no. If you have high quality cable, looping it should not impact performance or SWR in any way. Even if you have poor performing cable, the chances of you creating just the right size coil to create performance problems is fairly low. However, not impossible.

 

3.) I think you mean SWR and Reflectance. Line loss is always measured as a positive DB and the smaller the number the better. Line loss describes loss in the length of line, loss in connectors, etc. So, lets say you insert X amount of power... a line loss of 0.3 db is better than a line loss of 0.5 db.

 

Now, Reflectance, which measures the amount of back reflection created by a reflective event (i.e., high SWR) compared to the amount of power injected. It is the inverse of return loss. Reflectance is always a negative number and the lower the number the better. So a reflectance value of -30 db is better than -15 db, for example.

 

Collectively, line loss and reflectance determine how much energy radiates out of the antenna and how much is reflected back to the radio. Based on what the VNA shows, you are only losing about a 10th of a watt. A moderate gain antenna will more than make up for it.

[n4gix]

Regarding the nanoVNA, turn OFF the traces you don't actually need to 'de-clutter' the display.

[tweiss3]

So, moving on to my wife's car, the second TK-8150 is going to be installed, main unit in the back and remote head somewhere up front. Its a 2015 Transit Connect with the roof rack, see attached photos (pulled from the internet). Seeing as we use the roof rack quite a bit, for lumber, drywall and a snail pack when going on long trips, I did attempt to debate drilling the roof, but decided against it since it would make the antenna useless on road trips. 

 

In talks with Mark and his comet hood mount on his jeep, do you think it would work ok on the back hatch? I will be using the same Tram 1126 1/4 wave antenna. I guess I don't understand the ground plane with these mounts. 

 

Thanks!

[kidphc]

Another option but gives up some ground plane (thus giving some weird patterns) is to use a lip mount on the trunk or a mount that bolts into the hood hinge. Then you could cram a 1/2 wave on it.

 

Unfortunately, all the options will kinda interfere with drywall on the roof.

[tweiss3]

I was talking about a lip mount shown by Mark here:

 

http://fiveguysracing.com/marc/HAM-GMRS/Comet_Mount_And_Tram_Antenna_.jpg

 

Only installed on the lip of the rear hatch, next to the hinge. 

[kidphc]

I was talking about a mount like the following. All mounts as far as mobile (hell even base stations) for the most part are all compromises. It is what you can live with when it comes to compromises.

 

 

[tweiss3]

I was talking about a mount like the following. All mounts as far as mobile (hell even base stations) for the most part are all compromises. It is what you can live with when it comes to compromises.

 

 

 

 

 

I'll look into those. Where can I get one?

 

My concern there is my wife works at a hospital, and that might ask to be vandalized. High, dark and 6" in length would be hidden and less likely for her go get ripped off. 

 

The comet will also allow a 1/2 wave for road trips to get over the snail cargo holder. Is the hinge option an NMO?

[kidphc]

I'll look into those. Where can I get one?

 

My concern there is my wife works at a hospital, and that might ask to be vandalized. High, dark and 6" in length would be hidden and less likely for her go get ripped off. 

 

The comet will also allow a 1/2 wave for road trips to get over the snail cargo holder. Is the hinge option an NMO?

They are simple L brackets. You can mount an NMO to it like it was a roof. You just want to waterproof the under side.

 

Here is a thread on a guy making his own.

https://www.fordtransitusaforum.com/threads/two-way-radio-antenna-mount.38065/

 

Funny enough they are just ditch light brackets modded and labelled as antenna mounts.

https://www.gtv-van.com/en/hoodline-light-pod-antenna-mount-ford-transit.html

 

If you want easy just get a Comet or Diamond mount similar to Marc. Just make sure there is enough gap between the fender and hood before you slam it shut. Jeeps generally have a lot more slop to play with. For god sakes the hoods are still cinched tight with the elastic ties.

 

Does your wife use the GMRS radio often? If not then you could take off the antenna and store it. Putting a $6 NMO cap on it.

[tweiss3]

So it was difficult to track down, but I finally got manual information from Ford. UHF is ok in location 1&2, but im assuming this is for drilling only. Will I have an issue hanging it from the rear hatch using a lip mount?

 

Annotation 2020-06-03 160214(2) by tweiss3, on Flickr

 

Annotation 2020-06-03 160214 by tweiss3, on Flickr

 

Or do I just need to do a "wait n see" and drill if I have issues?

[n4gix]

Definitely 1 & 2 are for drilling. All of my antennas are currently mounted on the trunk of my Toyota Camry. While not ideal, I have had excellent results.

 

Keeping in mind that my major lobe for transmitting is directed to the front of my car, I'm not surprised if the reception is not as good when I'm driving away from the other station/repeater.

[kidphc]

So it was difficult to track down, but I finally got manual information from Ford. UHF is ok in location 1&2, but im assuming this is for drilling only. Will I have an issue hanging it from the rear hatch using a lip mount?

 

Although, not the most optimal location, close to the other options short of drilling. If you can keep the coil of the antenna above and away from metal you should be good. 

 

Here is some reading on placements of antennas.

Some more. Yes I know it is for a CB and a Jeep. It is just to help understand the type of directionality you get with the pattern.

 

http://www.mvaranet.org/uploads/2/7/2/2/27221859/1422988925.png

[tweiss3]

The comet mount came yesterday, and I'm rethinking not drilling. Interference when its open, and placing the antenna in front of the 3rd brake light.

In the above #2 location, am I to assume that is just in front of the rear cross member, where the headliner dips back up?

 

Is drilling as easy as this: http://www.satstar.com/LinkClick.aspx?fileticket=Z7UO3B-qIjc%3D&portalid=4

 

Do I need a hole saw bit, or will my nice machine drill bits work? I have a 3/4" traditional bit. Anything else I need to know, keep in mind, get for the install? For dielectric grease, just any old automotive dielectric grease will work?

 

Do I need to move the roof rack bar from the antenna 6"+?

 

Thanks,

[JJM]

The comet mount came yesterday, and I'm rethinking not drilling. Interference when its open, and placing the antenna in front of the 3rd brake light.

In the above #2 location, am I to assume that is just in front of the rear cross member, where the headliner dips back up?

 

Is drilling as easy as this: http://www.satstar.com/LinkClick.aspx?fileticket=Z7UO3B-qIjc%3D&portalid=4

 

Do I need a hole saw bit, or will my nice machine drill bits work? I have a 3/4" traditional bit. Anything else I need to know, keep in mind, get for the install? For dielectric grease, just any old automotive dielectric grease will work?

 

Do I need to move the roof rack bar from the antenna 6"+?

 

Thanks,

Yup, it’s that easy. Be careful with the bit. Some cut for a 3/4” inner diameter pipe. That would be too big. To check, take the ring off the NMO mount and see if the bit fits inside it (or inside the o-ring at least).

 

As for the grease: most antennas come with an o-ring or rubber gasket. I’ve never used grease and never had any corrosion issues when the rubber parts are used and properly tightened.

 

I tape off a 6x6 square, take my measurements to center the mount, mark, center punch, and drill.

 

Always be sure you have clearance (or control) so that you don’t punch through the headliner.

 

I didn’t read what wavelength antenna you chose but a rough guide is to make sure you have it’s length I’m clearance around the mount.

 

These things are super easy to do. I’ve done 6 holes in 3 different vehicles. I don’t even drop the headline, I just use a wire hanger to fish the cable over to the edge where I can pull the rest through (which reminds me, be careful pulling the coax through your new, sharp hole!).

 

 

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