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What kind of antenna would be used for 2-meters SSB mobile operation?

Discussion in 'VHF/UHF - 50Mhz and Beyond' started by KC0BUS, May 28, 2019.

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  1. WA9SVD

    WA9SVD Ham Member QRZ Page

    Do you have a sincere, dedicated cadre of other SSB ops in your location? Unless you have some (or several) local ops, a mobile installation is not worth much; you will NOT work weak signals with ANY mobile antenna, with some Es events as an exemption... YMMV
     
    W1TRY likes this.
  2. W1TRY

    W1TRY XML Subscriber QRZ Page

    The same can be said with respect to the vertical/horizontal discussion with respect to HF SSB. There's obviously a lot of mobile HF operation that is successful without horizontally polarized antennas. As with all things ham radio, put in the radio, put on a properly matched antenna and operate. Make some changes, repeat as necessary and report back. I think we'd all love to hear about your failures and successes!
     
  3. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    The vast majority of HF contacts are ionospheric; signals don't maintain polarization once refracted, so antenna polarization doesn't mean much.

    For very local contacts on HF ground wave (which is a thing, although most of us don't use it much), vertical polarization works much better (if both stations are vertical).

    On VHF, especially 2m and higher frequencies, the huge majority of contacts are not ionospheric and polarization holds over even long tropo paths; cross-polarization can sacrifice a lot of signal strength and home stations on SSB are horizontally polarized, so mobiles should want to be, also.

    Re working weak signals while mobile on 2m "weak signal" modes (everything other than FM), some guys do amazingly well. I don't know if Pat N6RMJ still has his stacked halos on his SUV but years ago when he did I used to hear and work him out to 150 miles away or so while he was just driving around on average terrain. And of course anyone who lives in hilly country might find opportunities to drive up to a hilltop or mountaintop and make 300-400 mile 2m SSB contacts from a mobile installation, taking advantage of the elevation.

    Another time when horizontal polarization helps (from a mobile) is in working satellites. A vertical whip might work with a sat close to the horizon, but "not for long." For higher elevation passes, especially ones almost overhead, horizontal antennas work much better. I remember working W5LFL on the Space Shuttle decades ago when Owen was the first astronaut to actually make any ham radio contacts from "space;" he was on 2m FM working "split frequency" and I really wanted to make that contact on that first day he ever did that, but it was midday and I was at work.

    All I had in my car was a 25W 2m FM mobile rig and a 5/8-wave whip. I drove the car to a local hilltop with a clear view for several miles in all directions and just barely heard LFL. Then in occurred to me he was passing nearly overhead -- I got a piece of rope from the trunk and tied it to the top of my 2m whip and folded it over so it was nearly horizontal. Signals picked WAY up and I made the contact on the next pass.

    [When Owen was scheduled to be a guest speaker at a Rocketdyne party several years later (around 1991 or 92) which I happened to attend as I was doing some work for them at the time, I brought his "shuttle contact" QSL card with me and met him after his talk, and he signed the card. Rocketdyne was the supplier of the SSME (Space Shuttle Main Engine) for the life of that program, and that's why he was there, to celebrate a long and successful run of SS engines.]
     
    KD0CAC, W1TRY and WA3GWK like this.
  4. W1TRY

    W1TRY XML Subscriber QRZ Page

    So, you're saying you roped him in, Steve? :p That's an excellent tactic! It reminds me that over the years I've seen military vehicles (typically National Guard) with the whips pulled over to front, assuming it was for clearance. I'm wondering if that technique is used during operation. Always learning from you Steve, thanks.
     
  5. K8JD

    K8JD Ham Member QRZ Page

    Ever hear of a BIG WHEEL antenna for 2M, I had one mounted on top or my service van for a while (Ca 1970) and wkd Detroit to Cleveland (100 + miles) On AM lwith about 10 W ! That antenna is essensially three halfwave dipoles bent into A BIG horizontal circle !
     
  6. K9STH

    K9STH Platinum Subscriber Volunteer Moderator Platinum Subscriber QRZ Page

    RZ:

    You are incorrect in your remarks that with antennas like Halo, Big-Wheel, etc., that the signal goes straight up. The height above "ground" plays an important part in the angle of radiation and that height is expressed in wavelengths. Starting at around 1/2-wavelength above ground the angle starts to lower to a very usable level and for the 2-meter band that distance is right at 41-inches. Such a distance above the body of the vehicle (usually the trunk lid) is very easy to achieve.


    TRY:

    As WIK has pointed out, once the signal reaches the ionosphere, the polarization becomes skewed and, as such, whether or not it started out horizontal or vertical, really doesn't matter. For line of sight, yes, polarization has a marked effect. But, once the signal is not line of sight, especially for HF, all bets are off!

    Glen, K9STH
     
    W1TRY and KD0CAC like this.
  7. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Sometimes it may be for clearance, but that's a common technique to make a mobile HF whip work better for NVIS propagation.

    NVIS whip operation.PNG

    The whole explanation is here: https://www.marines.mil/Portals/59/Publications/MCRP 8-10B.11.pdf?ver=2017-03-15-092827-423
     
    N7UJU and W1TRY like this.
  8. W7TRD

    W7TRD Premium Subscriber QRZ Page

    21559F5B-25F6-4BF5-BC48-EFF089A12B8E.jpeg Our Transportation division uses a similar emergency setup for NVIS / HF-ALE on their big rigs.
     
  9. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Yep, it certainly works!

    I was at Harris/RF Communications in Rochester, NY when that group (mobile HF design group) was testing such stuff on Jeeps and APCs in the parking lot. That must have been in '77 or '78.

    I wasn't part of that, just watched -- but it was interesting.
     
  10. KG5RZ

    KG5RZ Ham Member QRZ Page

    Wait a minute. I said "Now, since the original question was mobile SSB, we come to mounting the "halo, squalo, turnstile, or something similar" on a vehicle. Mount one of them to close to the body work you launch most if your signal straight up. Fine if you are working a geostationary satellite directly overhead. Not so great for working stations out near the radio horizon or beyond. So you mount the antenna up high enough the roof or deck lid don't act as reflectors. Now you are beating your antenna into every low hanging object around, especially if you use a 4X4 or a van for your rover.

    First you say I'm wrong then you go and restate the same thing I said, confirming it with dimensions. The roof of my 1 ton truck was right at 8 feet above ground and the roof of the E150 was just over 9 feet. Put a horizontal omni-directional antenna almost 4 feet above that you can forget about parking garages or the drive thru. There are several overpasses in the area I'd have to avoid for that matter. Driving through the state park on the way to the hill top operating position would have to be done after dismounting the antenna. Kinda squashes the idea of mobile operating.
     

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