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Thread: Dual/Multi-band Mobile Antenna

  1. #1
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    Default Dual/Multi-band Mobile Antenna

    I will likely end up getting a new vehicle in the coming months and have been planning out the installation. I am adding a couple radios over what I have now so to keep the roof from being overly cluttered I am considering using a couple dual/multi-band antennas to consolidate a few of what would be a lot of individual quarter wave antennas.


    One option I am looking at is the PCTWSLMR multi-band antenna from PCTEL. Am I correct that this is the antenna being used for the APX8500? From the information I've found it appears this antenna performs well across all it's advertised bands, it is just rather large. I'm trying to grasp just how large and noticeable it is.


    I found a picture of a Fire/Rescue Interceptor Sedan in Maryland with two installed, but it's too close to really judge size all that well. I also found a single video on YouTube where the antenna was being tested. It is visible in a number of shots but the black antenna on a white Tahoe sticks out like a sore thumb.


    Does anyone happen to have a photo of an install they did? How does it compare to the size of the Laird WPD136?


    Foregoing the antenna covering 7/800 MHz, any thoughts or experience with the Comtelco A1131/A1132?


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    Full disclosure, I used to be a Comtelco sales rep. All manufacturers publish charts of the radiation performance of their antennas, I suggest you check them out. One thing that applies to all of these multi-band antennas, and in the most professional manor all other antennas, it is of utmost importance that you mount the antenna on a proper ground plane and not on the edge of a roof, fender, or "L" bracket in order to achieve the published performance. Most of the complaints I received about multi-band antennas regarding reception/transmission range could be traced to poor mounting location. This usually results in a steep take off angle of the radiation pattern. I.E., signal goes up into the air at a steep angle instead of horizontally. This applies equally to receive range, it is amazing how much range reduction occurs due to a bad antenna radiation pattern. For VHF you must have a good 18" of flat grounded metal surface surrounding the antenna base.

    You mentioned using a mutli-band antenna instead of quarter waves. You should note that a quarter wave antenna typically has a take off angle of around 30 - 40 degrees, which is great for working into tall towers, tall buildings, and mountain top repeaters. A half wave, no ground plane antenna will have a nearly flat take off angle, which works best for flat, open range land and gives maximum horizontal range. The multi-band is going to fall somewhere in beteen, so choose wisely.

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    We use the Stico on the 8500 mobile.
    TRI BAND ROOF MOUNT ANTENNA*
    Designed for Software Defined Radios
    • Single port allows for VHF/UHF/7-800 MHz operation
    • Value priced with excellent performance
    • Complete system includes mast, base, cable kit and choice of connector
    • Also available with mast only – for use with existing NMO base

    Model Numbers
    • RFMT-TB-V/U/C
    • RFMT-TB-V/U/C-A (Mast Only)

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    http://www.panorama-antennas.com/sit...&description=1

    Just need an NMO adapter if you need something other than M6 threads. Decent antennas and NOT a giant base like the others.

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    For sure these would be permanently mounted with as much surrounding ground plane as I can get. One of the driving factors of moving away from all single band antennas is to get the fewer antennas more centered for ground plane reasons while keeping good spacing between the antennas.

    Something about the Stico just seems...odd, but thanks for the recommendation. I have a wideband VHF Panorama and am happy with it. I have not had any problems with the stud mount it uses, and it's smaller size compared to a NMO allowed me to mount it in one of the roof channel ridges allowing me to keep the antenna centered.

    Both don't quite have the bandwidth I'm hoping to get, though. Ideally I'm hoping to cover about 144-160 and 420-470, though I'd be willing to compromise to 440-470. I don't absolutely need 7/800 but it could be beneficial.

    Back to the PCTEL, I finally googled enough to stumble across a picture of it mounted from a distance. It is big, though not quite as scary as it first seemed. Link for anyone interested.

    Looks like I have a few options. Thanks for the info.

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    "Both don't quite have the bandwidth I'm hoping to get, though. Ideally I'm hoping to cover about 144-160 and 420-470, though I'd be willing to compromise to 440-470. I don't absolutely need 7/800 but it could be beneficial."

    Unfortunately, multi-band and wide bandwidth are somewhat exclusive. To get that kind of bandwidth at a decent vswr you are pretty much limited to quartewaves. The Comtelco A1511A (A1511B for black) has a published bandwidth of 24 MHz at VHF, and 100 MHz at UHF. The other major manufacturers have the same thing. It's not magic, just the diameter of the rod and the base spring provide for the extended bandwidth. The amateur market is not large enough for the major manufacturers to focus on designing a multi-band antenna like you are looking for.

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    https://www.ebay.com/itm/VHF-UHF-700...QAAOSwsW9YzHZT

    RCMP evaluated every antenna they could find and have bought several hundred of these. Base is a bit fat, but they work very well.

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    I have one of the comtelco antennas. I believe its the A1511B but I'll have to check. I have no complaints other than the fact that I wish I had gotten an antenna with a spring. The whip is very thick and has 0 flexibility so tree branches are scary.

    A lot of the new police cars around me have been coming with the antenna that Command Comm posted. At first glance I thought they were pretty big and ugly but after seeing them a few times you don't really notice them anymore, also seeing them on more cars, it starts to look more normal. I'll try to see if I can come up with a pic.

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    Quote Originally Posted by cmdcomm View Post
    RCMP evaluated every antenna they could find and have bought several hundred of these. Base is a bit fat, but they work very well.
    Forgive the skepticism here, but why would the RCMP need several hundred of these? RCMP operates on incompatible systems on different frequency bands across the various provinces (IE, VHF Analog, UHF P25, 800 EDACS, etc...). I'm sure it's a great solution, but up here RCMP don't have any kind of national system, cars in each area have radios unique to the technology used in that area, so there's no need to have a multi band antenna (in my Province for example they use UHF P25 and only have lip mounted 1/4 wave antennas on the trunk).

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    Well in my city in CT the new cars were delivered with them or a similar looking antenna, and I haven't had a chance look one over yet to see if they are branded or not, and I haven't seen the specs or build out sheets on the cars yet to know specifics of brand/model and such. We are currently vhf only, although we are switching to a P25 phase 2 system, which (very) optimistically should be ready for rollout around Thanksgiving.

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    Quote Originally Posted by CQDX View Post
    Forgive the skepticism here, but why would the RCMP need several hundred of these? RCMP operates on incompatible systems on different frequency bands across the various provinces (IE, VHF Analog, UHF P25, 800 EDACS, etc...). I'm sure it's a great solution, but up here RCMP don't have any kind of national system, cars in each area have radios unique to the technology used in that area, so there's no need to have a multi band antenna (in my Province for example they use UHF P25 and only have lip mounted 1/4 wave antennas on the trunk).
    AFIK ALL RCMP patrol vehicles in Alberta will have multi-band mobiles and portables. I have started to see APX portables being used around Edmonton. I believe that they are using separate antennas for VHF and 700MHz here though.


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    They have purchased and are purchasing APX8500’s. They are also using our vhf,uhf,700/800mhz combiners for the vehicles that have 3 separate radios so they only have to install a single antenna.

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    I'm skeptical that the gain is flat over the entire frequency bands alone. I'd love to see a chart for that.

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    Quote Originally Posted by cmdcomm View Post
    They are also using our vhf,uhf,700/800mhz combiners for the vehicles that have 3 separate radios so they only have to install a single antenna.
    Got a link to those? The Panorama triplexers are solid but a little pricey for my poor-ass budget.
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    There are a bunch up on eBay right now, search APX 8500 and they'll pop up. Seems to be about $200 for the Motorola OEM one.
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    Quote Originally Posted by KK4SDN View Post
    There are a bunch up on eBay right now, search APX 8500 and they'll pop up. Seems to be about $200 for the Motorola OEM one.
    Looks to be Motorola Part# EQ000103A02. Quick search shows they can be purchased from reputable resellers such as Wiscomm and RadioParts for the same price without the hassle of dealing with the fun of eBay.

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    Maybe it's just me, but something seems odd that the RCMP would be purchasing several hundred quantity of an antenna that appears to be sourced only from an eBay auction. Meanwhile other agencies have deployed APX8500 radios in the field with multi-band antennas available through more normal commercial channels.

    I looked a little deeper and can say I'm impressed with the breadth of items in the seller's other auctions. Anywhere from a TYT portable radio to expensive outdoor grills, with pretty much any type of used, refurbished, or brand new radio from multiple manufacturers in between.

    One thing I found interesting is the picture of the tag for the linked antenna, and at least one other similar one, seem to be cropped so as not to show the actual manufacturer's name. A NMO mag mount in another of the seller's auctions is clearly described as a Tram Browning item and has a picture of a nearly identical looking tag, though the manufacturer's name is photo-shopped over with the seller's info. I also see a heavy presence of other Tram antenna products in the listings.

    In addition to the overly generic website with all links leading to the Contact Us page, the majority of the sellers eBay auctions appear to end with the same "We have 100+ of these..." and a willingness to work with Federal, State, and local agencies for purchasing needs by contacting them.

    Like I said, maybe it's just me, but something seems odd about all this.

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    I do agree with that, and am reasonably sure that the antenna is a Browning, given that the antennas I mentioned in my previous post were Browning and look identical to these, and if you look up the claimed specs of the Browning, they are similar to what is claimed by this seller.

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    Browning BR-137 is the antenna model.
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    Waiting for cmdcomm to identify what it is he is selling. Is it the Browning, or another Chinese knock off? Also provide a radiation performance chart with manufacturer identification.

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    I think Browning _are_ all Chinese knock-offs today anyway. This has been a popular thing nowadays, like beer companies, where current modern companies are buying up the names of old well-known ghost companies and using them for their former name recognition on cheap ass Chinese stuff. Tram, Browning, and a few other popular CB mfr. names from the 70s are being used. Same as Bell & Howell, and many others used to market cheap junk consumer electronic stuff on TV. Same with beer, brands like PBR, Hamms, etc. are being brought back, again for the former popularity and name-recognition those brands used to have.

    As far as the actual products go, some of them are of acceptable quality - like most of the current Chinese import stuff these days, varying from POS to passable.

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    Quote Originally Posted by bstafford View Post
    Well in my city in CT the new cars were delivered with them or a similar looking antenna, and I haven't had a chance look one over yet to see if they are branded or not, and I haven't seen the specs or build out sheets on the cars yet to know specifics of brand/model and such. We are currently vhf only, although we are switching to a P25 phase 2 system, which (very) optimistically should be ready for rollout around Thanksgiving.
    The ones on the Middletown cars are Motorola ones, They don't work well at all

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    I see. Well I stand corrected then

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    The one I received is marked "Made in Taiwan", need to install one and sweep it with the 8800SX and LLRB.....can post after completed.

    The card on the bag is made to look like classic Browning fare. Fire up those Golden Eagles, Gents!
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