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What is the best 2M mobile antenna?

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by W5XXL, Nov 28, 2010.

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  1. W5XXL

    W5XXL Ham Member QRZ Page

    Hi there, I am sure this topic has been beat to death but I dont have time to search the forums right now.


    What is the best 2m mobile antenna? I am looking for the biggest, baddest antenna around. I like high gain numbers.

    I have found the Diamond NR22L antenna that boasts 6.2 DB of gain. Anyone have any experience with this antenna or know of a better one? I do not care how long it is.

    Thanks,
    Wesley
    KF5IKO
     
  2. AG3Y

    AG3Y Guest

    6.2 dB gain over what ? They don't say, and manufacturers specifications, especially when it comes to antenna gain are often misleading.

    You need to ask yourself a few other questions. You say that length is not a problem for you. Does that imply that you are NOT going to be using the antenna in a mobile situation? If you are, you have to consider if there are any places that would cause problems for you, if the antenna were too long/tall. Parking garages, bank drive-ups, etc. can all cause problems with your antenna, if it is too long.

    Why do you need a lot of gain? Are you a long ways away from repeaters? You realize don't you, that vertical antennas are most often, if not always used in FM/repeater operation, and horizontal antennas are employed for SSB and other simplex situations. These two different forms of communication often require different antenna setups.

    If you are thinking of something like moonbounce, you are going to want a huge array constructed of several long yagi beams, mounted on a BIG rotator setup.

    As I said, that 6.2 dB of gain ( not DB , big difference ! ) really doesn't amount to much of anything in the real world. Just 1 S unit.
     
    Last edited by a moderator: Nov 28, 2010
  3. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    The Larsen NMO-150 5/8-wave whip screwed into a roof mounted through-hole NMO mount is almost impossible to beat with anything.

    The installation and whip location play a major role in performance. The center of the roof is always best for a VHF or UHF whip of any kind, and the NMO mount is zero-loss, very waterproof and very strong. It's a Motorola design and nobody's come up with anything better.

    This combination also happens to be remarkably inexpensive! It's all American-made of very high quality materials and is widely used by professionals.
     
    WD4OTY likes this.
  4. AG3Y

    AG3Y Guest

    Wouldn't you have to put a ground plane under it, to get the best performance out of it, Steve? I realize that it would just be three or 4 19 inch rods, but I would think they would be necessary.

    What say ?
     
  5. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    That's what the car roof is for (ground plane). The center of the roof is the best ground plane surface there is on a vehicle unless the roof's made of a non-conductor (like a Corvette). It's also the highest point on the vehicle, providing a horizon advantage.
     
  6. KA0GKT

    KA0GKT Ham Member QRZ Page

    AG3Y wrote:
    As I said, that 6.2 Db of gain ( not DB , big difference ! )


    Actually, it is dB, neither DB nor Db. The unit is the Bel, named for Alexander Graham Bell of telephone fame, so the letter "B" would need to be upper case. deci, notated by the lower case 'd' has been in use since the late 1700s to mean one tenth.

    Never mind, AG3Y caught the typo ... my bad.
     
    Last edited: Nov 28, 2010
  7. VK1OD

    VK1OD Ham Member QRZ Page

    Notwithstanding that antenna manufacturers often make exaggerated claims (ie they lie), you can reasonably assume that gain without a reference qualification is wrt isotropic.

    The simple definition of gain is GAIN=DIRECTIVITY*EFFICIENCY, and DIRECTIVITY is simply the power density in the direction of interest divided by the power density averaged over the entire sphere.

    The promo stuff for that antenna that I found stated clearly but variously gain 6.5dBi and 6.2dBi, 6.5dB and 6.2dB. Some retailers have access to better stock?

    Owen
     
  8. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I'm sure that's it. The ones with more gain have silver plated the whips and such.:p

    What's unfortunate is the gain figures, if they were true and accurate, assume an infinite ground plane beneath the antenna, generally. And of course a zero-loss connection to the antenna, and a zero-loss transmission line.

    Then silly users mount them on angle brackets on the sides of trunk lids and such, with a length of 1/8" diameter (or smaller) coax to get past the gaskets and into the trunk, and the cable itself has 1 dB loss or worse because it's so tiny.

    It's all silly stuff. If you watch what the commercial installers use, at least here in the States, it's all better stuff such as Larsen antennas on NMO mounts -- on police cars, rescue vehicles, etc. I don't see any of them using Comet or Diamond or any of that, ever.

    When I'm mobiling down the freeways and using 146 MHz FM it's common to come across other hams doing the same thing. No matter what the others are using, my Larsen NMO whip on the roof of my van beats everybody. This is easy to tell, all we have to do is be next to each other and both transmit at the same time on the same frequency to a repeater, anywhere, and then ask the listeners, "Okay, who did you hear?" I never lose, unless I come across somebody with a taller vehicle and the same antenna.:p

    I did lose this, recently, when the guy in the next lane had a Larsen NMO whip in the center of his motor home roof, which was eleven feet high...his antenna was five feet higher than mine, no fair.;)
     
  9. VK1OD

    VK1OD Ham Member QRZ Page

    Like Steve, I have found a good implementation of a 5/8 base loaded vertical in the centre of a large roof to work markedly better than a quarter wave, or a multi-band wonder.

    My 5/8 was made thirty some years ago by a local manufacturer of commercial mobile antennas, separate coil assemby, and thin tapered stainless whip, all on a 'Belling & Lee' style antenna base. The fact that is in use over such a long time attests to the robust construction.

    NMO mounts are hardly used here, though they are cheap, robust and work well. Local dealers sell US stuff at double the US$ retail amount, which given the near parity of the currencies, seems a bit expensive.

    Steve, I am also a little surprised by the claims of 6.5dBi. It seems a little extravagant, and as you say, probably at least another dB at 2m for line loss.

    I briefly entertained using LMR195 for the fitting to my current car... but only briefly.

    Owen
     
  10. W6CD

    W6CD Ham Member QRZ Page

    I agree - the Larsen NMO-150 5/8-wave whip well mounted on the vehicle is a good way to go for mobile 2M. They work well and hold up very well over the long term.
     
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