[Antennas] Multiband Vertical Versus Multiband Dipole (HF)

2002年10月29日 17:21:26 +0000

It is incredibly difficult to make accurate measurements to evaluate 
relative performance, but relatively easy to evaluate them with a modeling 
program. Even the free version of EZNEC does this well.
I used the free demo EZNEC to design and evaluate my 10 meter 1.25 (approx) 
wavelength vertical dipole (EDZ) before putting it up a year ago. From the 
standpoint of its freq response and feed impedance, etc, that I observe 
now, the design data was right on. I presume the actual gain and pattern is 
as well.
The bottom is about 10 feet up, over poor ground. It gets out. I have 
nothing to do an actual real-time A--B comparison with.
It took an hour or so to see how to use EZNEC without the manual. The 
manual is free also for those who want more.
For more serious use, MultiNEC would even let you vary the height among 
multiple automatic runs and let you observe the effect you are interested in.
Jerry W4UK
At 16:01 10/28/02 -0800, Jan Reimers wrote:
>Why does everyone discuss this subject from standpoint that a vertical is by
>default not a dipole?? Can anyone comment on the relative performance of
>the a veritcal dipole and a quarter wave with (good) radials? I would also
>be interested to hear how important is the distance from ground to the
>bottom of a vertial dipole?
>>Cheers
>Jan (VA7JNR)
>> > -----Original Message-----
> > From: Dave Fouchey [mailto:[email protected]]
> > Sent: Monday, October 28, 2002 6:56 AM
> > To: Linden, Mike (BRC-Hes); [email protected]
> > Subject: Re: [Antennas] Multiband Vertical Versus Multiband
> > Dipole (HF)
> >
> >
> > Mike I can't provide definitive data but only anecdotal
> > experience. I have
> > used Dipoles and verticals often over the years. Dipoles in
> > general have
> > behaved better for me than MOST verticals. the exception was
> > when I used
> > verticals over a very extensive ground plain, in this case
> > salt water, at
> > which point they blew the Dipoles away for DX performance.
> > the only caveat
> > there was that they were prone to pick up more impulse noise and storm
> > static than dipoles but the difference in long haul performance was
> > striking. As it is I use both to this day, with a good ground
> > radial system
> > under the vertical. Your mileage may vary of course.
> >
> >
> > 73's
> > Dave
> > WA4EMR
> > Sterling Heights, MI
> >
> > At 08:01 AM 10/28/02 -0600, Linden, Mike (BRC-Hes) wrote:
> > > A lot of folks still say that a vertical radiates equally
> > poorly in all
> > >directions (they should only be used if you don't have space
> > for a "real"
> > >antenna). After researching it a bit, it is my contention that such
> > >verticals don't have an adequate ground system or are being
> > used in areas
> > >with poor ground conductivity. My goal is to have some sort
> > of support for
> > >most of the bands between 10 and 80 meters.
> > >
> > > I'm currently running a homebrew multiband coaxial trap
> > dipole in my attic
> > >at about 25 feet. However, I'm thinking ahead to when I have
> > enough time and
> > >when I can convince my housing association to let me install
> > some outdoor
> > >antennas. My two HF options would be a multiband vertical (I like the
> > >Butternut HF9V) or a multiband dipole (I've seen some
> > designs that only add
> > >significant loading on the lowest bands).
> > >
> > > Personally, from an aesthetic point of view, I like the
> > vertical. I would
> > >be able to install it more than 30 feet from my 2-story
> > vinyl sided house
> > >and would have enough room for 30 foot radials in all directions. The
> > >antenna would be ground mounted. Ground conductivity in my
> > area (far west
> > >Chicago suburbs) is quite good. My primary concern with the
> > vertical would
> > >be increased noise due to vertical polarization. Any comments on how
> > >manageable the increased noise is and how much worse it is
> > than a dipole?
> > >Based on my research, the primary benefit of a vertical is
> > the low angle of
> > >radiation that results when used with a good ground system.
> > >
> > > The dipole installation would not be as aesthetically
> > pleasing as the
> > >vertical (at least from my perspective -- hi!). Due to the
> > lack of older
> > >trees in my new subdivision and the layout of my lot, the
> > dipole would have
> > >to run from my house straight into the back yard such that
> > the feed point
> > >would drop in my back yard 30 or 40 feed from my house.
> > Probably the best
> > >height I would be able to manage would be about 30 feet
> > above ground --
> > >perhaps a bit lower at the far end -- I would also need to
> > come up with some
> > >sort of middle support. Based in my research, the benefit of
> > the dipole
> > >would be lower cost (about 100ドル) and lower noise level.
> > However, at 30 feet,
> > >the angle of radiation would not be very good for DX.
> > >
> > > I'd appreciate feedback from folks who have had the chance
> > to compare the
> > >performance of multiband verticals with multiband dipoles.
> > >
> > > Thanks, Michael N9BDF
> > >
> > >
> > >
> > >