Beam Vs. Vertical

Discussion in 'VHF/UHF - 50Mhz and Beyond' started by KC3AZG, Sep 3, 2014.

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  1. KC3AZG

    KC3AZG Ham Member QRZ Page

    Looking to add a new base station antenna of my 2 meter mono band setup soon. Work mostly Fm. I am debating if a hi gain beam, I have found some in the 15 DBI range or a long vertical Omni directional, I found most with a gain of 7-9 DBI. Mounting and such is not much of a concern as I am handy and live in the country. I would welcome any feedback on the subject or any antenna brand/model suggestions. The radio is putting out 75 watts and I am looking for maximum distance. It didn't make sense for me to go with an amp until I get a good antenna system.
  2. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    If it's for FM work, you definitely want it to be vertically polarized, to be compatible with what everybody else uses. For SSB-CW or any kind of "weak signal" work, horizontal polarization is used. There are valid reasons for this in both cases.

    A 15 dBi beam is going to be long and very directional, so of course you'll need a rotator and a sturdy support; and there are tricks to installing a vertically polarized beam antenna and having them work properly. A 7-8 dBi omni is a lot less work, and no tricks involved other than getting it up high and at the top of its support mast.

    For maximum "range," two key points are coax line loss (the lower loss, the better) and antenna height above ground, and especially height above local nearby obstructions like houses and such.

    I've been on 2m FM since 1966 and have built and owned several 2m repeaters from coast to coast and would say that with few exceptions I'd rather have a simple ground plane (2.1 dBi gain, maybe) up 100' above ground, fed with hardline, than a big beam with a rotator at 25' above ground, fed with anything. The 100' high ground plane will nearly always do better at most all locations. One exception might be if you already live on a dramatic hilltop with an amazing view of a distant horizon in all directions; then, a lower beam might actually work better than a very high vertical. But for "most of us," the higher antenna will outperform.

    So basic recommendations are: Think "height," think "strength," think "low cable loss" (whatever that takes).
  3. AA9G

    AA9G Premium Subscriber QRZ Page

    WIK gave you everything you need to know. I am planning on putting this Cushcraft up. Excellent gain, easy to switch from FM to SSB modes.
  4. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Are you going to use two feedlines, or just one with a 90 degree phase delay line between the two feedpoints?
  5. KC3AZG

    KC3AZG Ham Member QRZ Page

    Thank you all for the advice. I think a vertical is the way to go.
  6. WB9UDA

    WB9UDA Ham Member QRZ Page

    Well.......from an old salt......if you put up a vertical and feed it with 75 watts (I think that's what you said) then you're spreading your power out over a 360 degree circle, so the amount of power that actually gets to any point on that circle is 75 divided by 360 (more or less, depending on distance).

    But with a beam, with 12 to 16 db Gain, you're focusing all your power to a target only a few degrees wide.

    I've run both in years past and I never had any antenna talk to the horizon and beyond, with the clarity that I got with my 20 Element Co-Linear Beam antenna. The forward gain was phenomenal, and the front to back rejection was GREAT! It was like an RF canon.

    So get the biggest antenna that you have room for, and that you can afford, and feed it with all the power you can muster and you'll have the most fun. I did!

    From my Yeasu mobile which I also ran on base and a 200W amp, I talked all over Illinois and beyond with that beam.
    Sorry I don't have a pic of that beam. I don't think they even make them anymore, but the beam shown above sure looks interesting. Wish I had one.

    I have plenty of room on my 1.25acre country lot to swing a big beam, or even Stacked beams, but I just don't have the money to buy one. lol
    Most good beam manufacturers, also make stacking kits with co-phasing harnesses.

    So for now anyway, I'm stuck with a little vertical. (Diamond X-30A, for $69.95 at AES)
    Oft times, what we really want and what we can afford, are two totally different things.

    Cheers Mate..... post pic's of your new antenna, when you get it.

    WB9UDA :cool:
    Last edited: Sep 6, 2014
  7. AA9G

    AA9G Premium Subscriber QRZ Page

    2 lines I think
  8. KC3AZG

    KC3AZG Ham Member QRZ Page

    Thank you. What amp are you running? That my next VHF project after the dust settles on getting the antenna up and such. At what point is an amp more helpful than gain on 2 metere?
  9. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Two lines works fine.

    But you can actually use one line if you install a 90 degree phase shift network between the two driven elements. That's about 13.5" of RG-213/U or 16.75" of LMR400, etc. Works fine and saves the cost of one feedline.

    I've used them both ways, don't notice much difference one way or the other but my wallet is heavier with the single feedline.:p
  10. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I've been running a kilowatt on 2m since about 1968 (sometimes actually 1500W output) and would say:

    On FM, that's silly power and nobody should do that. 100-150W output on FM keeps up with just about everything and more than that just makes you an alligator.

    But on SSB-CW (weak signal work), a kW can certainly be helpful, especially when working other stations running similar power and delving into "way, way, way over the horizon" tropo contacts.

    With a good (horizontally polarized) beam up high, a low-loss feedline, a good receiver, and a "decent" location, 2m SSB-CW contacts out to 350-400 miles should be a daily occurrance almost anywhere. Farther if you're on a hilltop, maybe a bit less if in a valley...but it's pretty typical.

    The "up high" matters much more than the power.
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