[LCC] 80 meter antenna recommendations?

[Steve Lott]

I have a Sturba Curtain and have had very good results with it
I belive you have plenty of room for one there Mark


http://www.w8ji.com/curtain%20sterba%20USIA%20array.htm


cheers !

steve
KG5VK

On Thu, Sep 27, 2012 at 10:10 AM, Marshall Stewart <marsh at ka5m.net> wrote:
> EZNEC+ 5.0 calculates that a flat top 80M dipole up 55 feet will have max
> gain at 90 deg elevation – straight up.  At 75 feet up, the max gain will be
> at 55 deg elevation.  An inverted vee with the apex at 75 feet up (max gain
> at 75 deg) will be better than the 55-foot high flat top, but not as good as
> a 75-foot high flat top.  The gain of an inverted vee is down slightly from
> a flat top with the apex of the vee at the same height as the flat top.
> Given my choice of #1 or #2 below, I’d opt for #2.
>
>
>
> For max gain at a low take-off angle and a deep overhead null on 80M, a
> vertical starts to look like a good way to go.  A full-length (approx 65
> feet) vertical radiator is preferable over any loading method used to
> resonate a shortened vertical radiator.  On 80M #12 wire is so thin relative
> to a wavelength, the Q of the antenna will be high, and the 2:1 SWR
> bandwidth narrow.  To cover the entire 80M band, the vertical radiator would
> need to be about 3 feet in diameter – not very practical.  A wire “cage”
> with multiple parallel wires separated by an insulator with all parallel
> wires connected at each end could be used to make a “fat” conductor.  Bigger
> would be better.
>
>
>
> Radials – most Amateur Radio ops just don’t have the real estate to install
> the ideal 120 radials each ¼ wavelength long.  To reduce the number
> required, an alternative of above-ground radials might be a solution.  The
> elevated radials can be shortened with inductive or linear loading.  I’d
> stay away from a ground rod and 1 long radial – the feed point impedance
> might be good and the SWR low, but the ground losses will be high and the
> antenna efficiency low.
>
>
>
> Two possibilities that may or may not be practical in your situation:
>
> A dipole hung from a tall tower like a guy wire.  At the center feedpoint, a
> rope continues on to the ground, and the “second half” of the antenna goes
> back to the tower - like an inverted vee hung vertically from a tower with
> the apex pointing away from the tower.
> A lazy H (vertical dipole with end loading) hung between 2 supports (towers,
> trees, masts, etc.) fed at the bottom.  The vertical part of the antenna
> 40-feet in length with 38.3-foot end loading wires could be starting
> dimensions. (The vertical part attaches to the center point of each end
> loading conductor.)
>
>
>
> Sources:  ARRL’s Vertical Antenna Classics, The Antenna Handbook, Antenna
> Compendium Vol 1
>
>
>
> In your case what would I go with?  #2 with the apex as high as possible for
> NA, and # 3 with as many radials as possible each as long as possible (or
> elevated radials) for DX.
>
>
>
> I’d be interested to know what you decide to put up for 80M.
>
>
>
> 73,
>
> Marsh, KA5M
>
>
>
>
>
> ________________________________
>
> From: lcc-bounces at louisianacontestclub.org
> [mailto:lcc-bounces at louisianacontestclub.org] On Behalf Of Mark, K5ER
> Sent: Wednesday, September 26, 2012 4:54 PM
> To: lcc at louisianacontestclub.org
> Subject: [LCC] 80 meter antenna recommendations?
>
>
>
> Okay, now its my turn to ask the group. HFTA doesn't model these
> combinations, and I'm not good enough with EZNEC to trust I get them built
> right within that software. I plan to review info from the antenna book, as
> well as Low Band DXing, but there is collectively A LOT of knowledge within
> this club, so I'd like to tap into that, too.
>
>
> I need to replace my 80 meter antenna, and am considering three options:
> #1. go back up with a flat top dipole (actually, center always seems
> slightly below ends) height abt 55 feet
> #2. replace with inverted vee - feedpoint can be about 75-80 feet
> #3. ground mounted vertical - feed point at 6" above ground, one #12 thhn
> conductor running up in an oak tree, one ground rod and (maybe) only one
> radial.*
>
>  *The #3 antenna started out from the NCJ article last year "an easy
> inverted-L for 160. They showed with only ONE radial, it should give close
> to a 50 ohm match, not needing a tuner or inductor/capacitor tuning at base.
> Since there are FAR more contacts on 80, as compared to 160, I could convert
> this inv-L to a vertical by simply cutting off the excess (leave it about
> 67' long). My issue here is I buried hardline from shack to feedpoint (about
> 260 feet), but did not realize I had used 75 ohm hardline for the last 120
> feet of the run. I may have a mis-match to deal with at the feedpoint, so I
> would need to address that. On the radial issue, I only have abt 30 feet of
> yard in one direction, and the septic field lines are in the other, so a
> complete set of radials is out of the question. I might be able to get 4-8,
> MAX, but only if my wife goes somewhere for a weekend this winter and I get
> them stapled in without getting caught.
>
> Everything I have seen on other reflectors compares flat tops and inv-vee's
> at the same height. I have read that a inv-vee is better for DX, but also
> read that at the same height an inv-vee is 1/2 to 1 db down from a flat-top.
> Because of tree location, in my case, the inv-vee feedpoint would be higher,
> (20-25') than I could get a flat-top.
>
> My standard reply when someone ask me about antenna is "who do you want to
> talk to?" Although I enjoy SWEEPS, I haven't worked it from home is several
> years. I do not regularly participate in 80 meter traffic nets, (though it
> would be nice to be able to check in during emergency situation). I DO like
> the NAQP contests in January and July. I have recently become more
> interested in DX, and should have 4 band DXCC within a month or two, but I
> am only 1/2 way there on 80, so I guess my primary focus will be DX, but
> without giving up "some" domestic. There is a chance I could get away with
> EITHER #1 or #2, and still do #3 as well.
>
> What would YOU put up, and why?
>
> Thanks and 73,
> Mark, K5ER
>
>
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