Railfan Technology > Mounting a scanner antenna in a vehicle

i haven’t had a scanner in my car for several years now, but having retired recently, I now have more time to railfan. 

But there’s a hitch:  my current ride is a Subaru Forester with a retractable sun roof. So a permanently mounted rooftop antenna appears to be out of the question. There’s a nice cubby in the dash that would hold a small scanner just fine, and I suppose I can go back to a magnetic mount antenna with the cord stretched out a window, but I’d really rather not. 

Any suggestions on what to do about an antenna mount?

[[ Partially off-topic:

Aren't in-vehicle scanners still illegal in the Empire State unless the driver has Ham Radio credentials? If the ban has been rescinded, it's news to me. (Corrections welcomed!) I don't want you to inadvertently get zapped by the po-po while you're out and about peacefully railfanning in NY. ]]

My guess would be that there would be space at the far rear of the roof of the vehicle for a drilled antenna mount.  I would suggest consulting a professional commercial radio shop--a good shop knows the "tricks' of where to mount antennas on most any vehicle.  The shops also know how to route  antenna cable so that it does not interfere with air bags and other vehicle components.  For SUV's that might have any garage clearance problems with a roof mount antenna, I also recommend the Sti-co Flexi-whip antenna.  They live up to their name and seldom give problems in parking garages, etc.

In the distant past I used one of those glue-on through the window antennas with decent results. I haven't found one on the market recently although there are a number that are close to it. Apparently they don't work well on a window that has been darkened, although I'm not sure if they mean a factory darkened window or one that's had a darkened layer added to it afterwards. Definitely something to be concerned about if transmitting.

I've seen Foresters with metal antenna antenna added to just above the brake light assembly. Not sure how easy that would be to do.

+ Just looked at a selection on Amazon, I should add that an antenna can make reception worse by adding cable loss and just bad performance. I've been very happy with a Yeasu and a good antenna sitting in the coffee cup holder, or velcroed next to the window. It goes againest lots of theories and also catches some odd intermods every so often, but it also catches a lot trains.



Edited 1 time(s). Last edit at 12/25/18 22:10 by TCnR.

Inside antennas are not as good as an external antenna.  However, I remember from a few years ago that our police department had some antennas mounted on the rear deck inside the back window, behind the rear seat.  Our county police were on VHF with antennas about 18" long.  The city police used UHF with 5 or 6" antennas and usually had a baseball hat over them.  Having the antenna as close to the window as possible is probably a good idea.

John
 

just put it towards the rear in the middle, unless your going to cargo boxes up there I would think
 

A VHF antenna inside a vehicle can sacrifice one-half or more of its performance.  Poor idea.  "Through the glass" antenna mounts also sacrifice a chunk of performance.  There is no free lunch here.  A good quality exterior antenna, properly mounted, is the best solution.  If one is concerned with receiving only the strongest radio signals, then any old antenna mounted anywhere might do.  Most railfanning, however, requires being able to receive transmissions that often have pretty weak signals.  The best performing radio in the world is pretty much worthless when connected to a crap antenna.

I recently purchased a magnet mount antenna that is specifically tuned to the 160 through 162mz range. It is fantastic and pulls in traffic like no other antenna I have ever had.
The key thing I have to consider is not slamming the cable in the door as I have with past antennas. I run it in through a window and leave the a good distance between the glass and the frame. As long as I care for the cable, the antenna will last forever.

It would be nice to have a permanent mount, but in my case, I can work around it with great success.

A good antenna is the key. The best radio in the world is pretty much worthless without one.

Well looks like we're going down that road again. In a perfect world they have perfect antennas and lossless cables, guess where we live.

The best set up I've had was a 0.2 microvolt receiver with a 5/8 magnetic mount on the roof. We can complain about the antenna cable hanging across the roof and the cable hanging down from the window. We can complain about the rain coming in through the window, we can stand up high and point out that the first time the window was closed it damaged the cable and we never heard the best performance. How about the left over cable coiled up under the seat sitting next to the car's data bus, lots to complain about there. How about those crimped on connectors, poor bend radius under the dashboard? OMG what if the train's radio doesn't work? Or they're on the wrong channel? But I have photos of those trains because there's more to catching a train than having a radio. Then there's what you do when you find a train.

It depends on what you're looking for from the hobby. Listening to every train from train on the continent is a little impractical. In that sense there's all sorts of data out there that you don't get to access if you're listening to a radio. What if you do miss a train...

What about all those trains that you missed while your car was in the shop getting the antenna installed? It can get really silly.

TCnR,
Am sitting here LMAO.......Did the Grinch steal your Christmas???  But your comments are so true. I bought a Motorola 99 channel back in 2006, that was railroad surplus. Yes it is capable of Receiving and tramitting, but never hooked the transmitter part of the radio up. It receives like a charm. I paid $125 for it at the time. It’s programmed with all 99 channels.  Everyone at the time was talking about how digital was coming and all these radios were going to be obsolete. We’ll here we are going into the 13th year later and it’s still usable and working like a charm. By the time it becomes obsolete, am likely going to be to old to use it. 

Its has a Motorola magnet mount antenna, it’s tuned for the 160-162 VHF frequency range. These were the same style antenna we used in public safety.   The police used to hang them upside down in the trunk of their cars. I like all the newer equipment, one mentioned one above, but when am sitting with a group of people and my radio is the only one receiving the dispatcher or trains, go figure. 

There’s allot lot of good used commercial equipment available out there, at dirt cheap prices. One should look past, what everyone has or says to buy, but what gets the job done. As TCnR has commented

Have a Great New Year

Dave in PA



Edited 1 time(s). Last edit at 12/28/18 04:38 by video7105.

I used a mag mount 2m antenna at the rear of the roof on my 2009 Forester with good results.  I was able to run the cable (RG-58 size) in the back hatch at one corner without doing any damage to it, or having any problems with water ingress.  The door gasket is well hidden inside the hatch, so that probably had something to do with it.  I did have to add an extension cable to whatever was already on the antenna, but that gave me a chance to hide the bulky UHF to BNC adapter under the rear floor mat instead of trying to attach it to teh radio.  On the older 2001 Forester, I ran the cable in at the corner of one of the side windows.  With no upper window frame, the wire tucked in nicely there too.

The 18" long antenna did hit sprinkler pipes in the parking garage at work, but wasn't a serious problem.  I would think a 5/8 wave antenna would be out of the question if you have to regularly park or drive in a low clearance area.  I could still get pretty reliable reception out to 10 miles or so, depending on terrain (it always depends on terrain!), with the 1/4 λ.

GTD

I have used a tuned Larsen 2 meter antenna on a magnetic mount. The rectangular mount always worked well until I bought a 2016 GMC Terrain. I have had to use a flexible insulated wire wrap to anchor the antenna base to a roof rack cross member. Otherwise meeting semis in windy Wyoming two lane roads will blow it over nearly every time. I suspect the roof steel thickness in new lighter vehicles is not thick enough for the magnet to hold.

Since the railroads have gone to narrow band my old radio shack under the dash picks up more static. The old railroad radio man says that is account there is 1/2 the signal width compared to the old broadcast transmissions.

My next railroad chase vehicle is coming with an aluminum body, what then? It's a Rivian not a Ford.

fbe Wrote:
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... what then?

Aluminum works as a reflective surface, that's a large function of a ground plane. A friend in Idaho used RTV to stick a piece of steel to his camper roof.

Or use RR Radio smartphone Ap.

My antenna is an old magnet mount in the trunk and works fine for 42 mhz CHP, RR, aircraft, and 400 mhz sheriff, and this is in the desert with transmtters on mountain tops instead of in town.

Bill Deaver
Tehachapi, CA

That is going to take a lot of courage to stick a plate of steel to a brand new pick up. Can't we invent a laser projection of an antenna which will receive radio signals using a lens about the size of a silver dollar flush mounted to the roof?

These truck mounted antennas are becoming popular in the Midwest, seems like they would solve a few of the G/T questions on TrainOrders. Of course they are the wrong frequency but that never stopped a heated discussion.



Edited 1 time(s). Last edit at 12/29/18 22:49 by TCnR.

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RRBadTrack Wrote:
-------------------------------------------------------
> I recently purchased a magnet mount antenna that
> is specifically tuned to the 160 through 162mz
> range. It is fantastic and pulls in traffic like
> no other antenna I have ever had.
> The key thing I have to consider is not slamming
> the cable in the door as I have with past
> antennas. I run it in through a window and leave
> the a good distance between the glass and the
> frame. As long as I care for the cable, the
> antenna will last forever.

I started with a budget setup about 10 years ago, Uniden handheld + $25 magnetic mount external antenna + Diamond RH77CA when away from the car. I cut the mag mount antenna to railroad frequency, mainly as an excuse to get addional overhead clearance. I've been taught (from various sources) that antenna length isn't too critical for receive only use, as long as the antenna isn't too short.

Another factor to consider is antenna's mounted height. I've noticed while driving along freeways with sound walls (Hwy 99 south of Sacramento) that my reception suffers when the signal source is close. I've driven through the same area with higher height vehicles (SUVs) with the same setup, and crew conversations and hotbox detectors come in clearer, and this is consistent. FYI, this isn't a scientifically-controlled analysis, just an observation, so take it with a sprinkle of salt.

I mention this, because using the antenna inside a vehicle will likely have the height disadvantage compared to roof mounts. This in addition to the handicap WW mentioned above.

I still use the same setup as 10 years ago. It's easy to pack for travel, and I can use it on almost any rental car, except for convertibles where I have to mount the antenna on the trunk or near the hood. 

I currently use a Diamond K400S trunk antenna mount, plus the 2 meter antenna element that goes with it. Works fine for railroad listening as well.

 

cph Wrote:
-------------------------------------------------------
> I currently use a Diamond K400S trunk antenna
> mount, plus the 2 meter antenna element that goes
> with it. Works fine for railroad listening as
> well.
>
>  

Those are interesting, I've seen them but never found an outlet for them.

I Googled the model info, there's a number of sellers, I looked at the Amazon website and they have a number of additional mounts offered from other manufacturers. t4p.

Google also offered a couple of installation videos, one shows using a mount lower on the hatch door, maybe that's what I had seen at the brake light housing. That install doesn't clear the roof, they are using it for a large whip antenna, I'll have to check this out.



Edited 1 time(s). Last edit at 01/01/19 22:58 by TCnR.

Having done variations of all of the previous suggestions for antenna mounts, here's what I currently run and am happy with it.  I have a Ram 1500 truck and use a 2-meter Ham antenna mounted to a bracket on the left side front fender, just outside the hood.  I was able to get a model-specific bracket for my truck that simply bolted to one of the existing fender bolts - https://www.dxengineering.com/parts/cma-dg2antpf  .  I dont' know if there are any custom brackets for a Forester but they do make generic ones that you might be able to use.  Onto this I put a Coment VHF/UHF antenna - https://www.dxengineering.com/parts/cma-sbb-5nmo  .  

Advantage to this setup is that the overall antenna height is not much more than the factory AM-FM radio antenna, and it doesn't really stick out visibly much like something mounted on the roof would do.  The reception is pretty darned good, although certainly not as omnidirectional as if it would have been mounted smack dab in the middle of the truck roof (but I have a sunroof, too).  Sure, it took a little work to route the cable through the firewall of the truck, but I was tired of always putting up the magnetic antenna I had been using for several decades before.  It's nice to simply hop in the truck and turn on the radio (I use a Kenwood TM-281) anytime I want to go somewhere, railfanning or not.

MAB
K0MAB