What is the best 2M mobile antenna?

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

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  1. K1DNR

    K1DNR Ham Member QRZ Page

    Being the cheapskate that I am, I own two el-cheapo brand NMO mount antennas that are designed for 2m/70cm operation. Both claim gain figures that I ignored.

    On one of them I can permanently bend the whip with just my thumb and forefinger. Its really poorly made.

    Both are mounted on NMO outfitted magnetic mounts.

    One sits on the railing of my fire escape (don't tell) and I made a set of 2 meter and 70cm radials for it.

    The other stays in the car. Its a lease. I don't have any practical means of drilling a hole in the roof and my wife would kill me. I also operate V/U FM mobile only on rare occasions.

    Performance: I can access all the desired local FM repeaters with no problem using my HT's 5 watts through 8' of RG58. The mobile antenna stays inside the vehicle except when I use it. It performs significantly better than either the HT antenna, or a roof mounted 2m 1/4 wave vertical on a similar magnetic mount.

    Clearly its not the best way to do things. But it works for the application.
     
  2. KG4ZAR

    KG4ZAR Ham Member QRZ Page

    I'm sure Larsen makes good gear but I've been using 5/8 wave NMO roof mount antennas bought at almost half the price of the major name brands and they have done extremely well. They are sold at hamfests for $20 or so.

    I live in the "rolling hills of the Bluegrass" area of Kentucky. Not the mountains but very hilly terrain and the 5/8 wave on the roof is the way to go. With this set-up and 25 watts I'm solid into repeaters 45-50 miles away on my one hour morning commute.

    If you are strictly on open roads with no low-hanging trees there is one other antenna that does beat the 5/8 wave,but I don't know if it is still available. That's the Hustler 2 meter co-linear. It's almost seven feet tall and(I think) 1 and 1/4 wave. When I really need my signal to get out of the valley I pull that one out of the truck bed and mount it up!

    By all means go with the NMO roof mounted antennas if you can. You eliminate the static noise problems you get with mag mounts and the grounding(lack there-of)issues associated with other antenna mounts.
     
  3. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    That's really the lesson. For working almost every repeater within 50 miles of here, I can use a VX-150 hand held and its rubber duck (flex) antenna inside my van and hit all of them with a good enough signal that people answer me.

    That takes "no antenna at all.":p It helps that most of our local repeaters are up several thousand feet above sea level and line of sight to everywhere.

    The real tale is told when trying to work simplex, mobile to mobile. With an HT and inside antenna, that might work for 3 or 4 miles, then it just gives out. With the same HT and a mag mount on the roof, maybe 10-12 miles.

    With the same HT and the NMO-150 5/8 wave whip on a thru-hole mount in the middle of the roof, more like 25-30 miles. With my 70W mobile rig and that antenna, more like 40-50 miles.

    Larsen makes a pretty decent mag mount base for the NMO whips; it's engineered about as well as one can be, with a large coupling area and a thin Teflon insulator, coupled via a robust aluminum base that's directly connected to the feedline outer conductor. I really can't think of a better way to do this; but it's still about 3 dB down from a "direct connection," with a through-hole NMO mount.

    I've punched a hole in the roof of every vehicle I've ever owned or leased. Nobody cares. If my XYL ever said a word about this, I'd be shocked. Not just shocked, but letting her have it with both barrels about all the stuff she does that I'd prefer she didn't.

    She would never want to hear that.:p
     
  4. K1DNR

    K1DNR Ham Member QRZ Page

    I'd like to see the look on the garage attendants face when I got on the roof and started drilling... :p

    Maybe I could drive out to the country and find some secluded spot.

    Oh well. It keeps things pretty hidden from potential thieves...

    The fire escape one has a metal mount that is connected to the coax braid as well - which made it a natural for ground radials :) If I thought we were going to be here long term I'd take my chances sneaking something up on the roof. Few people would see it. And I highly doubt the Super would turn me in to the co-op board, although my wife might... she's on the board... :p I have to be extra good or else people will want to mount their satellite dishes, etc... (nope, no satellite dishes allowed...)
     
  5. N1RKW

    N1RKW Ham Member QRZ Page

    Let's keep this simple: The best antenna is one that works.

    I'm running a Gam SS-2 (half-wave) on a mag-mount fed with nearly 20' of rg-58 coax... Despite all of these performance no-no's, I routinely work repeaters 40 - 50 miles distant.

    I really don't think I'd gain anything by switching to a low-loss coax and NMO mount - I'd still be working the same repeaters 40 - 50 miles away - And I'd have an empty wallet and a hole in the roof of my car.:(
     
  6. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I agree, the requirement is all application-driven, like most requirements.

    If all you ever work are the same strong repeaters, you may not need anything more than the "rubber duckie" on a hand held.

    When I operate VHF mobile, most of my contacts are simplex, and often with other mobiles running simplex. The best installed antenna extends range quite a lot, as does more power on both ends.
     
  7. K9STH

    K9STH Platinum Subscriber Volunteer Moderator Platinum Subscriber QRZ Page

    Not only are the Larsen antennas excellent performers, they last basically "for ever"! I have a couple of NMO-150 antennas that I obtained back in 1970 that are still working fine. The design of the coil has changed somewhat in the physical sense over the years, but the performance is still the same.


    As for antenna gain: There are at least 3 different ratings.

    dBi = gain over an isotropic source

    dBd = gain over a dipole

    dBwn = gain over a wet noodle

    Many antenna manufacturers seem to use the dBwn figure!


    Scientific notation generally indicates a lower case letter indicating 1/10th and an upper case letter indicating time 10. Therefore, dB = 1/10th of a Bel and DB = 10 Bels. As such, a DB is 100 times a dB.

    Glen, K9STH
     
  8. VK1OD

    VK1OD Ham Member QRZ Page

    The International System of Units (SI) uses symbol d for deci as a multiplier prefix to mean one tenth, and symbol da for prefix deca to mean 10. 1dB is equal to 0.01daB.

    The lower case / upper case thing you propose is not part of SI, for example the SI symbol for 1000 is k, so we have km, kΩ, kW, kVA.

    The upper case is used for the unit designation if it was a persons name, so m for metre (not a person's name), S for Siemen (a person's name), Ω (upper case Omega) is for Ohm (a persons name).

    DB is just plain wrong, as others have noted.

    Owen
     
  9. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    We used to use dBgcl = dB over a garbage can lid.

    You left one unit out, Glen: The Clarabel (cB) as pictured.
     
  10. K8JD

    K8JD Ham Member QRZ Page

    Hustler made a mobile colinear with a quarterwave lower section and then a phasing section and a top 5/8 wave section.
    This may still be available.
    Maybe the best long haul 2M FM mobile ant. I worked some long distance simplex with this setup.
    Beware of going under low hanging branches . This ant is over seven ft tall.

    Roof mounting is the way to go, I have seen these mounted on a bumper, counterproductive at the least.
     
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