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:[email protected]] Sent: Sunday, September 08, 2013 12:24 PM To: Charlie Cunningham; 'James Rodenkirch'; 'Mike Armstrong'; 'Tom W8JI'; Shoppa, Tim; [email protected] Cc: [email protected] 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:[email protected]] On Behalf Of James > Rodenkirch > Sent: Sunday, September 08, 2013 11:00 AM > To: Mike Armstrong; Tom W8JI > Cc: [email protected] > 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: [email protected] >> Date: Sun, 8 Sep 2013 07:18:18 -0700 >> To: [email protected] >> CC: [email protected]; [email protected] >> 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" <[email protected]> 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 > > _________________ > Topband Reflector > > _________________ > Topband Reflector > > > ----- > No virus found in this message. > Checked by AVG - www.avg.com > Version: 10.0.1432 / Virus Database: 3222/6147 - Release Date: 09/08/13 > _________________ Topband Reflector
