I'll do the 3/8 wave case later, Carl. I didn't have time to get back to it
today because I got all bolluxed up trying to include an attachment to my
reflector post. Also, even trying to embed the document in the body of a
reflector post didn't seem to work. Must have made the posting too large for
the reflector to accept.
Later,
Charlie, K4OTV
-----Original Message-----
From: Carl [mailto:km1h@jeremy.mv.com]
Sent: Sunday, September 08, 2013 12:24 PM
To: Charlie Cunningham; 'James Rodenkirch'; 'Mike Armstrong'; 'Tom W8JI';
Shoppa, Tim; w7dra@juno.com
Cc: topband@contesting.com
Subject: Re: Topband: 5/8 wavelength vertical is mo betta than
shorterversions??
Include the 3/8 wave while you are at it.
And thank you for doing this.
Carl
KM1H
Subject: Re: Topband: 5/8 wavelength vertical is mo betta than
shorterversions??
> Jim, Mike et al:
>
> I've been putting together a document along with some models, plots etc.
> that addresses the 1/4, 1/2, 5/8 wave vertical question, and I hope,
> illustrates where some of the confusion arises - especially with regard to
> the 5/8 wave case. The answers are not so simple in that case, and are
> dependent on distance, frequency, time of day, and ionospheric conditions.
> Please keep your cool and bear with me. Maybe we can shed some light on
> this
> complex issue, with a little less heat and cussin' and discussin'! I'll
> post
> the document on the reflector as an e-mail attachment.
>
> 73,
> Charlie, K4OTV
>
> -----Original Message-----
> From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of James
> Rodenkirch
> Sent: Sunday, September 08, 2013 11:00 AM
> To: Mike Armstrong; Tom W8JI
> Cc: topband@contesting.com
> Subject: Re: Topband: 5/8 wavelength vertical is mo betta than shorter
> versions??
>
> Mike: I apologize if my query came across as an insult!! Mea culpa sent
> from out here in the black hole of 160 meter communications - s/w Utah.
> I think I said I wasn't doubting your claim and I wasn't questioning your
> "conclusions" - just attempting to find some modeling or Measures of
> Performance to substantiate it as, lately, I have been seeing/reading of
> anecdotal "evidence" and I, for one, am interested in supporting
> data/measurements.
> I use/employ a 43' vertical on 160 through 17 but can't compare it to a
> 1/4
> wave over the same radial field -- certainly your closeness to the water
> may "answer" or provide a reason for your success with a 5/8 over 1/4 so,
> with the modeling info I supplied perhaps someone who knows the modeling
> apps(s) could do some "investigating" in the form of modeling to answer
> that?!?~!
> OK?? 72, Jim R. K9JWV
>
>> From: armstrmj@aol.com
>> Date: Sun, 8 Sep 2013 07:18:18 -0700
>> To: w8ji@w8ji.com
>> CC: topband@contesting.com; rodenkirch_llc@msn.com
>> Subject: Re: Topband: 5/8 wavelength vertical is mo betta than shorter
> versions??
>>
>> Tom (and James),
>> I am well aware that my comments concerning the 5/8ths wave was based
>> upon
> subjective/anecdotal evidence. I am in a science (Astrophysics) by
> profession..... I do know the difference. HOWEVER, I cannot completely
> throw out the simple fact that when I altered my 20 meter omni antenna for
> Winlink to the 5/8ths, that I received UNSOLICITED comments from the
> system
> users stating (100 percent of them) that my signal was much improved into
> the areas they happened to be sailing. None of those people, not a single
> one, knew that I was changing my antenna. The purpose being just
> that.....
> to see if anyone complained or said anything else concerning performance
> from THEIR point of view. In reality, THAT is the point when supplying a
> service..... What do the USERS think of the performance, not what I think
> or
> what a FS meter says.
>>
>> Even if I had the equipment to measure the performance and the equipment
> says that my signal should be improved, but the Winlink user comes online
> and universally states my signal sucks, I will REMOVE that antenna. I
> know
> that isn't likely, but if the modelling software states the signals should
> be worse and they are, 100 percent, reported as improved, then there is
> something at play that the modelling software isn't taking into
> account........
>>
>> Not arguing, just answering that initial question that from my EXPERIENCE
> with that antenna, it works better than the quarter wave at the same
> locations I happen to be...... AND ONLY ON 20 meters. I won't speak to
> any
> other band, although I would think it would work there, too, because I
> have
> not put one up for those other bands.
>>
>> As an aside, alot of folks are using that so-called non-resonant vertical
> antenna that is roughly 43 feet tall....... They seem to be having some
> success with them on the bands. Physically, they are pretty
> convenient.....
> and on 20 meters, they happen to perform pretty well, judging from user
> comments, anyway..... and at that band, it is roughly 5/8 wave in
> electrical
> height. So, again, I find it interesting that actual experience argues
> with
> the modelling software (in MY particular instance). But, again, in my
> case
> IN HAWAII, I had an outstanding location that, for some reason I don't
> know,
> happened to favor the 5/8 by alot more than even the theoretical gain
> would
> indicate. NOBODY would comment, much less 100 percent of commentors, on a
> slight gain of 2 db. Heck, that wouldn't be worth the effort. However, I
> think you are quite right, Tom..... something else is at play.... ground
> clutter (I had some.... loads of tropical trees and plants in the area),
> some significa
> nt
>> ly tall sailboat masts RIGHT ACROSS THE STREET from my house (very
> close), etc, etc. Then you consider the seawater ground that was so close
> by...... There are many factors to take into account, not much of which
> does
> a modelling software take into account. Undoubtedly the answer is there
> and
> not directly related to antenna gain. I did try elevating it on top of a
> 40
> foot pipe mast and using 8 resonant radials....... it made no difference
> except to increase the chances that high winds would knock it down. In
> terms of SUBJECTIVE performance and comments, no difference. So, I put it
> back on the ground and carried on.
>>
>> Remembering what the antenna was for, and where it was located, putting
>> up
> a horizontal 80 or 90 feet in height simply wasn't possible. The SERVICE I
> was providing required OMNI directional capability, so even a dipole would
> be unsat in at least 2 directions...... those being the directions an
> emergency call would not be heard...... Not a good situation for the given
> purpose, right?
>>
>> I will say that I didn't appreciate the comment concerning how I came to
> my conclusions about antenna performance. Insults only prove that one has
> run out of reasonable arguments..... and that is ALL it proves. Given
> that,
> this will be my last post here and I am likely removing myself from the
> list. Insults are NEVER science...... not now, not ever!
>>
>> Mike AB7ZU
>>
>> Kuhi no ka lima, hele no ka maka
>>
>> On Sep 7, 2013, at 18:59, "Tom W8JI" <w8ji@w8ji.com> wrote:
>>
>> >> The above modeling results just don't support that contention/posit so
> I'm wondering what else comes in to play that could lead folks to love the
> 5/8 wavelength vertical over a shorter version, regardless of frequency?
> I
> don't see one performance comparison that supports that claim. I'm not
> saying the "claiming person" isn't correct but....I don't see how!
>> >> Help - what am I missing here?
>> >> 72, Jim Rodenkirch K9JWV
>> >
>> > The 5/8th wave obtains the small amount of gain it has through effects
> of ground reflection. The current maximum is elevated, and that elevation
> causes additional phase shift with the illumination of earth out some
> distance from the antenna. The re-radiation of earth is sometimes
> explained
> by an "image antenna". The image antenna is a fictitious antenna directly
> below the real antenna, and this "image antenna" simply represents what
> the
> earth at a distance does from the illumination from the main antenna.
>> >
>> > The 5/8th wave moves the current maximum slightly higher than a quarter
> wave above earth, so the fictitious image moves slightly lower than a 1/4
> wave below surface.
>> >
>> > If you move the 5/8th wave above earth, such as in a groundplane well
> above the earth, the extra length no longer provides gain. Instead, it
> actually reduces gain at low angles.
>> >
>> > Another effect is the extra height above ground of the high current
>> > area
> can help get the antenna's main radiating area a little bit higher above
> ground clutter.
>> >
>> > This would also apply to an extended double zepp, where the second
> antenna half makes the image unnecessary. Each half of the double zepp is
> the image of the other side, so we don't need earth.
>> >
>> > So it is a very specific benefit from the 5/8th wave caused by moving
> the current height up above a reflecting surface, or in the case of a
> double
> zepp moving current away from a second identical element while still
> having
> a common center feedpoint.
>> >
>> > One of the biggest antenna hoaxes played on people was the 5/8th wave
>> > CB
> groundplane antenna. Two meter 5/8th wave groundplanes are the same. The
> work on the broadcast band to increase groundwave signal because soil is
> often reasonably low loss on the AM BCB. If the soil out some distance
> from
> the antenna is lossy, or if it does not exist, the 5/8th length causes
> increased low angle loss.
>> >
>> > This is why when you look at models, outside of specific cases like
>> > some
> cases of low broadcast band use, we have a tough time seeing the gain
> imagined or claimed. A field strength meter has an equally difficult time.
> :)
>> >
>> > 73 Tom
>> > _________________
>> > Topband Reflector
>> _________________
>> Topband Reflector
>
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