Hi, Carl
Well, yes, high angle radiators have a definite advantage in dealing with
hilltop or mountain top repeaters as I pointed out in one of my earlier
posts/replies. My experience with 160 is significantly more limited than my
VHF/UHF experience, and my experience with high angle radiators on 160 is
limited!
Regards,
Charlie, K4oTV
-----Original Message-----
From: Carl [mailto:km1h@jeremy.mv.com]
Sent: Sunday, September 08, 2013 4:54 PM
To: Charlie Cunningham; 'Shoppa, Tim'; rodenkirch_llc@msn.com;
armstrmj@aol.com; w8ji@w8ji.com
Cc: topband@contesting.com
Subject: Re: Topband: 5/8 wavelength vertical is mo betta thanshorter
versions??
Contrary to one persons views that 2M ham 5/8 antennas are pure rubbish
sounds about what Id expect from a flatlander.
As anyone who has spent decades in a hilly or low mountainous area knows,
the 5/8 antenna can knife edge refract over hills via that high angle lobe
and access the wanted repeater. At other times the multipath is tolerable
but annoying. The 5/8 also helps in concrete canyons.
I have several VHF/UHF commercial repeaters here on top of the highest hill
in 20+ miles and the users select the commercial mobile antenna that works
best for them. They are a mix of simple 1/4 wave for the close in locals to
a selection of 5/8 and collinears, all from recognized commercial antenna
manufacturers, for those requiring a lot of 20-50 mile travel ranging from
the ocean to the 200-700' hills of NH and MA.
It has also been shown time and again that a high angle can be very
beneficial on 160 DX as shown by the success of inverted L's and a low
inverted V or dipole.
I owe several new DXCC to a low inverted V and would not be without the V
and 1/4 wave vertical with elevated radials; they complement each other.
If you live in another part of the country or world things may be different.
Carl
KM1H
----- Original Message -----
From: "Charlie Cunningham" <charlie-cunningham@nc.rr.com>
To: "'Shoppa, Tim'" <tshoppa@wmata.com>; <rodenkirch_llc@msn.com>;
<armstrmj@aol.com>; <w8ji@w8ji.com>
Cc: <topband@contesting.com>
Sent: Sunday, September 08, 2013 1:12 PM
Subject: Re: Topband: 5/8 wavelength vertical is mo betta thanshorter
versions??
>
>
>
>
>
> All,
>
> There has been a lot of "cussin', and discussin' " on this reflector
> regarding 5/8 wave and shorter vertical and perceived merits. There have
> also been perceived insults, irritation and hurt feelings!
>
> I spent a little time last night and some this morning modeling some of
> these cases with EZNEC. I chose 40m, because I had an array stored, that
> I
> could pull out the driver and use it as a quick model, without doing a lot
> of construction with EZNEC. In the attached Word document there are
> figures showing the antennas and their current distributions along with
> elevation plots and data. See above.
>
> All of the radiators were modeled above 4 elevated resonant radials at 10'
> above real high-accuracy ground.
>
> Note the following:
>
> * The gain of the 1/2 wave vertical increases approximately 0.3 dB
> over the 1/4 wave ground plane, and its takeoff angle is reduced about 5
> degrees, from 22 degrees to 17 degrees. (The angles are, of course, height
> dependent.)
>
> * Neither the 1/4 wave or half wave verticals have any noticeable
> high-angle radiation.
>
> * The 5/8 wave radiator brings the main lobe down another 3 degrees,
> from 17 degrees to 14 degrees elevation and the main-lobe "gain" is
> increased another 0.2 dB., but, in this case, there is a high-angle lobe -
> that peaks above 50 degrees elevation, and is only 2 dB below the main low
> angle lobe.
>
>
> It is this last point that has led, I expect, to most all of the differing
> perceptions of the merits ( or lack of) of 5/8 wave verticals!
>
> When we consider HF propagation via the ionosphere, the high angle lobe
> can
> produce a reflected sky wave that can produce either destructive or
> constructive/reinforcing interference with the lower angle main lobe
> signal!
> ( If we were discussing VHF/UHF we would call this "multi-path"
> interference!)
> So the result is that at varying distances from the transmitter we can can
> have concentric bands or areas of either constructive, or destructive
> interference.
> All of this is further complicated by different atmospheric ionization
> conditions in different directions from the transmitter and time of day (
> where the "terminator" or grey-line is) etc.
>
> So the perception of whether a 5/8 radiator may be superior or inferior to
> a
> shorter radiator, can be very dependent on distance frequency, time of day
> etc.
> If one has a regular schedule with a fixed end point, or endpoints, that
> happen to lie within a region where there tends to be constructive
> sky-wave
> reinforcing interference at that frequency and time-of-day. But this is
> unlikely to be true on all paths, I expect.
>
> I hope this helps to shed some light, but this is all the time that I can
> put into it at this time. My apology!
>
> Best regards to all!
> Charlie, K4OTV
>
>
>
> -----Original Message-----
> From: Shoppa, Tim [mailto:tshoppa@wmata.com]
> Sent: Sunday, September 08, 2013 11:27 AM
> To: 'charlie-cunningham@nc.rr.com'; 'rodenkirch_llc@msn.com';
> 'armstrmj@aol.com'; 'w8ji@w8ji.com'
> Cc: 'topband@contesting.com'
> Subject: Re: Topband: 5/8 wavelength vertical is mo betta than shorter
> versions??
>
> I have been told by others, (treat as hearsay), that for AM broadcasts the
> 5/8 wave produces a pattern with destructive interference between skywave
> and groundwave at medium distances at revenue-important times of day e.g.
> "Drive time".
>
> Tim N3QE
>
> ----- Original Message -----
> From: Charlie Cunningham [mailto:charlie-cunningham@nc.rr.com]
> Sent: Sunday, September 08, 2013 11:17 AM
> To: 'James Rodenkirch' <rodenkirch_llc@msn.com>; 'Mike Armstrong'
> <armstrmj@aol.com>; 'Tom W8JI' <w8ji@w8ji.com>
> Cc: topband@contesting.com <topband@contesting.com>
> Subject: Re: Topband: 5/8 wavelength vertical is mo betta than shorter
> versions??
>
> 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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