2m Mobile Placement & Wave

Discussion in 'Mobile Radio' started by N0BEC, May 22, 2014.

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  1. N0BEC

    N0BEC Ham Member QRZ Page

    I am very new (just got my ticket at the beginning of the month) and I currently only have a Baofeng UV-5RA HT. I am noticing that I tend to want to use it in my car, but even with a non-rubber duck antenna I can only hit a very close repeater. I want to get a mobile rig, but money is tight and I cannot afford a dual-band mobile rig, so I am going to focus on 2m as that is where Skywarn and a good percentage (30-ish in 25-miles) of close repeaters are.

    What I am wondering about is antenna placement and wave.

    I understand that an antenna, mounted in the middle of the roof, is ideal for signal strength. But will I see much of a difference if it is trunk lip-mounted near the rear of the car? Also, 1/4 or 5/8 wave, will that make much difference in that mounting location? I looked for 1/2-wave, but they seem to be to expensive.

    Grant - KE0AJL
    Twin Cities, MN
     
  2. N7WR

    N7WR Premium Subscriber QRZ Page

    I'm a little confused as to whether you are getting a 2 meter mobile now or want to use the handheld in your car with an external antenna. Yes, center of roof mounts are the best but a trunk pip mount should work OK with a 5/8 wave antenna. You should be able to reach a number of repeaters if they are within 25 miles of you with your handheld and an external antenna---depending on terrain. Welcome to ham radio and have fun
     
  3. WA4OTD

    WA4OTD Ham Member QRZ Page

  4. AD5CL

    AD5CL Ham Member QRZ Page

    I used a 1/4 wave mag mount and an HTX 202 for many a mile commuting. I have a nice 5/8 wave mag mount Larsen that did not appreciably improve what the 1/4 wave did most of the time working machines in the range we are working with. Drove company cars so I had a "go bag" with the cig lighter thingy for battery conservation, speaker mic and the NMO mag base with the screw on wire whip. Had a cloth bag it all dropped into which formed the whip into a permanent parenthesis, lol. Also kept a RatShak 2m amp (5w in and 40 out or summink, I forget) and a twin lead j-pole in case I went up in the hills and wanted to act all important and stuff working 2m smpx from some rare piece of dirt, a few hundred or thousand feet above the valley floor. Still got all that stuff. Somewhere...................
     
  5. N0BEC

    N0BEC Ham Member QRZ Page

    @N7WR: Sorry, I would like to get a separate mobile rig for mounting in my car instead of trying to use my HT.

    @WA4OTD: Thanks for the link. I looked at some of the info there, but being new to most of this I am not sure that I am reading the info correctly.

    From what I see it appears that the 5/8 radiates well, up to about 60-degrees from the horizon, but there is some loss at 45-degrees.
    The 1/4 on the other hand only radiates well, up to about 50-degrees with some loss at about 25-degrees.

    Overall the 1/4 wave will give the best overall coverage, while the 5/8 might seem to be a bit more spotty as the degrees from the antenna to the repeater change.
    Does that seem to be correct and/or others experiences?

    Also, I know that the coverage is really only a factor when at the edge of what the antenna is putting out, so with a mobile rig putting out 50W (understanding that I would power down as needed) would there really be a difference, or would I be not near the edge of coverage?

    Thanks for all the answers and info so far!

    -Grant - KE0AJL
    Twin Cities, MN
     
  6. KD8NGE

    KD8NGE Ham Member QRZ Page


    First, I see from the nature of your comments that you are researching your subject.
    Well done. Please continue; answers you find for yourself tend to stick with you.
    Now as far as a hand held used for mobile --
    I did exactly that until I could afford the dual band mobile.
    My solution was a Diamond mag mount and I'm sorry I don't remember its particulars, only that it had a really good magnet and I was really, really careful to make scrupulously certain the base was clean before plunking it on the roof of my new Jeep Liberty. (Magnets pick up ferrous crud, and a shocking amount of it! Learned that the hard way, hi hi!)
    There are many very good choices for antennas and radios.
    I won't presume to offer free advice on what you should do -- I will instead say that, for the interval until I could afford the mobile, I too ran a talkie on a mag mount, and had reasonable success to the local repeaters.
     
  7. AG6JU

    AG6JU Ham Member QRZ Page

    I found a cheapest place to buy 2 meter antenna on ebay. often if one buy directly from country where they manufacture, it seems cheapest. some of their quality is good enough, some need modifications to be used.
    I mount my 2 meter 1/4 wave antenna similar to this picture. On Front Hood. I bought my antenna on ebay for $10 free shipping from outside of USA. I can not mount antenna on Roof, because where I live there many park structures, maximum height limit is around 6 FT. and many drive through fast food also has low height limits.
    144mhz-ant-hood-02-sml.png
     
  8. KS2G

    KS2G Subscriber QRZ Page

    Grant ...

    The Larsen amateur radio antenna catalog has detailed explanations of the different mobile antenna types (e.g. 1/4 vs 1/2 vs 5/8 wave) and (on pages 16 and 17) a discussion of mounting locations --with an illustration showing dB losses for mounting locations other than center-of-roof.

    You can download the catalog at:
    www.pulseelectronics.com/download/3598/larsen_amateur_catalog_/pdf

    73,
    Mel - KS2G
     
  9. KE6KA

    KE6KA Ham Member QRZ Page

    I've used 1/4 and 5/8 wave antennas when mobile. A 1/4 wave will certainly work OK if you are using local repeaters. In fact, if that is all you do you aren't going to notice a difference between the two. I deciding on using the 5/8 wave Larsen because I often use repeaters that are many miles away, and my experience is the 5/8 wave gives me an extra 10 to 15 miles of useable distance in the fringe area of the repeater.

    The disadvantage of a 5/8 wave is that the top of the antenna bangs low-hanging tree branches, and of course, parking garages and drive-through windows. I took out several fluorescent tubes at a drive through window once. The sound of them popping followed by the sound of shattered glass falling on the truck was disturbing, to say the least.
     
  10. K0RGR

    K0RGR Premium Subscriber QRZ Page

    One thing about the Twin Cities is that the region is pretty flat. You want the antenna that concentrates the RF at the horizon, as much as possible. However, I think there is another big factor, and that is the overall height of the antenna. Here in the flatlands, the higher the antenna, the better.

    I have three different antennas that I swap around. The first is a short 1/4 wave unit that goes in and out of parking garages very easily. The second is a 5/8 dualbander. Mounted on the hood of my pickup truck with a trunk lip mount, it 'dings' the roof of the parking garage at Mall of America, but no damage. The third is a very tall 2 -5/8 wave antenna. Driving through the Twin Cities, and scanning all the repeater frequencies, I find that the longer the antenna, the more repeaters I hear. The 5/8 is the one I use most of the time. I do notice the difference between it and the 1/4 wave.
     
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