Topband: More anecdotal "stories" to cause one to stop and....

[Mike Armstrong]

Ashton, thanks.  I DO have  EZNEC and know how to use it pretty well (that is to say, I have used it to provide what-if results for antennas that are a bit more complex than a simple dipole..... like 4 element vertical phased arrays and antennas of that nature).  I definitely don't want to waste alot of copper or aluminum on a "dog," if I have an idea that may or may not be a great idea.  I do check my modelling results by comparing those results to the results of others who have modelled the same antennas so that I know I am doing it correctly.  Obviously, the ones I am comparing against could be wrong, but if they are there are a number of people, who have been published, making the same mistakes..... he he he.  

I will definitely try the overlay idea out.  That is one thing I hadn't done, but rather look at and compare the printed data in tabular format.  I DO like the idea of normalizing the data and looking at it graphically...... as they say, a picture is worth a thousand tables...... lol.

Thanks for the input, too.  It makes good sense, although the concept of the antenna being heard well at long distances, while attenuating high angle signals on receive seems to fly in the face of "low height" receive-only antennas being a "good idea."  ON THE OTHER HAND, I know that low receive antennas produce a decent signal not so much by enhancing the signal strength (because they don't do that), but by increasing the system signal to noise ratio which is certainly at least as important as gain, if not much more so.  "Gain" enhances noise along with the desired signal, as anyone who has spent more than 5 minutes listening to 160 knows (without a doubt..... he he he).  So comparing the two antenna types (xmit and rcv) is mixing apples and oranges since the requirements for each are separate and somewhat distinct.  At least. that seems to be the case on 160/80 and 40 (to a lesser degree).  Actually, I have used low noise receive antennas on 40 with incredible success.  I call it incredible simply because I would go from hearing absolutely no signals due to the noise level, to hearing a band full of signals, all of which were definitely strong enough to work (and then some).  Summer in  AZ and the wet season in tropical locations like Guam, Yap, PI and even Hawaii were incredibly noisy, as all of you know without a doubt.  Even a simple hand-rotatable "magnetic loop" antenna makes all the difference in the world.  I go from nothing but static crashes, and gawd knows what else, to a "nice" listening experience (defined as: the noise doesn't overrun signals and I don't get a headache after a few hours of listening..... lol).

Again, thanks Ashton..... and thanks especially for the "overlay" idea.  An idea so simple that I passed right over it.... :) :)

Mike AB7ZU

Kuhi no ka lima, hele no ka maka

On Sep 9, 2013, at 11:54, Ashton Lee <Ashton.R.Lee at hotmail.com> wrote:

> When you use antenna modeling software to look at a low dipole on 160 you note three things: 1) They are extremely high angle radiators and 2) Raising the height from say 10 feet to say 100 feet has essentially no impact on the performance, and therefore 3) At any reasonable height the antenna lacks the directionality you tend to want from a horizontally polarized antenna.  So low horizontal antennas look pretty bad at first glance.
> 
> When you model an inverted L with say a 60 foot vertical section and 64 foot horizontal run you get an antenna where the pattern looks pretty nice. Lots of low angle radiation. A pretty big hole in the vertical pattern.
> 
> But then if you overlay the two models you see something very strange. The Total radiation of the horizontal antenna (against normal ground, not sea water) is so much better that its effective radiation at low angles is about the same as the vertical. At most it's down 6 dB at 5 or 10 degrees depending on ground conditions, radial fields etc. When I model it I actually see less than this difference in my location.
> 
> So the fact that you can be heard by DX on a low horizontal isn't all that amazing. You have to have a pretty ideal vertical set up to beat it by a lot.
> 
> The real problem is that the low horizontal may not hear DX very well because it favors high angle radiation and the low angle inputs are a lesser part of the total reception. Receiving antennas fix that.
> 
> I think the bigger problem with horizontal antennas on 160 is that next to no one really has the room for them.
> 
> 
> 
> 
> On Sep 9, 2013, at 12:23 PM, Mike Armstrong <armstrmj at aol.com> wrote:
> 
>> Same here, guys.  Please do reply here and if someone "already knows everything," they need not even read the thread, right?  LOL.  I have heard, but don't know if it is a common mode of propagation or if it is very rare, like LDEs on 15...... They do happen, but it is as rare as hen's teeth.  I have heard it 3 times on 15 that I am aware.... But I digress, the mode I am wondering about, and it might explain why even I with a low horizontal on 160 have worked some decent DX (Chile, Japan, several Carib countries, and some pacific islands)..... Is "ducting" a common propagation mode on 160?  If it is, that could explain ALOT when it comes to high angle radiators working DX that they probably shouldn't even hear with such a setup.  
>> 
>> Any thoughts from those who would like to talk about the subject of high angle radiators (even NVIS), ducting and DX?  Quite honestly, during one particular 160 contest a couple of years ago, I worked 11 countries (all new for me) all over the place except europe...... As strange as it seems, those were the only countries that ANYONE in my area was hearing or working.  So here I was working the same DX stations that some guys with really decent 160 antennas were working, but MY antenna was anything but ideal........ 300 foot long OCFD (fed about 20 feet in from one side) and, this is the kicker, it is only up 50 feet in the air on one side and 40 feet on the other side (available trees, one of which is on my neighbor's property..... but she is my mother in law, so no legal issues there.... lol).  So how is it that I was working these stations with the same amount of effort as the guys who had "ideal" antennas, like full sized 1/4 wave verticals over an EXTENSIVE radial field.
>>  It was a very pleasant surprise, but not expected at all.
>> 
>> On later dates,I would hear people in the same areas of the world, but no matter how hard I tried, not able to work them..... although I HEAR them quite well on that antenna (it seems to be fairly low noise).  Something has to be "up," but I will be darned if I can figure it out..... unless there is some prop mode that is common to 160  and isn't on other bands where this type of antenna "scaled" in length and height would suck 100 percent of the time...... LOL.  Well, maybe not 100, but often enough that EVERY antenna book would say "get it higher in the air....  ALOT higher"
>> 
>> Thoughts from experienced 160 folk?  Again, only those interested in talking about this subject need respond. :) :)
>> 
>> Mike AB7ZU
>> 
>> Kuhi no ka lima, hele no ka maka
>> 
>> On Sep 9, 2013, at 8:56, Bill Cromwell <wrcromwell at gmail.com> wrote:
>> 
>>> On 09/09/2013 10:33 AM, James Rodenkirch wrote:
>>>> ...think that there's "more to understanding" horizontal and vertical antennas on Top Band.
>>>> Listening to a fella on 80 SSB this morning about his experiences with a vertical 1/4 wave and a horizontal loop on Top Band.
>>>> He said he had both up and used them over a 20+ year period and noticed that one would work better than the other for DX.  For five years or so the loop would outperform, for a couple of years the two would be equal and then for about five years the vertical would do better.
>>>> One can easily point to the 12 year period as aligned with the Solar Cyclef BUT -- when I look at the radiation patterns for both I see the loop as a hugely efficient NVIS antenna with little low angle radiation.  Sooooo, I think there are some magnetic anomalies at play here but -- if the radiation angles don't change, how does one work "mo betta" than the other?
>>>> I do have the ON4UN book and will start diving in to it more to see if John can shed some light on this topic AND I don't wanna start a cuss and discuss session here (I know many of you already understand what influences the above "observations" so I don't want to rekindle any previous "debates) but.....if someone can direct me to specific sections of John's book or lother papers/websites, I would appreciate it!!
>>>> I consider myself a "newbie" re Top Band" propagation and "other 'influencers'" on antenna performance (I do understand gray line, the various ionized layers and all of that) but anxious to learn more - thank you, in advance, for any "direction" you can point to so I can learn.  Replies off line are probably mo betta - don't need to get any pissin' contests agoin'!  Hi Hi
>>>> 72, Jim Rodenkirch                       
>>>> _________________
>>> Please reply on the list. I'm interested, too. My own suspicion is there are parts of propagation that are not very well understood if at all and those bits are pointed out by what happens with real antennas as opposed to theoretical antennas. That does not dismiss the theories.
>>> 
>>> I'm taking baby steps here and I am permanently limited by my postage stamp lot but we have all read testimony about success from small lots (and with low power). I'm cornering the parts to build a 'meter' that will give me information about the antennas I already have so that I might make them perform "mo bettah" - if I know whether to turn left or right when I get some 'numbers'.  Just like Jim, I am not interested in stirring up any pots. It's pretty easy with a 40 meter dipole antenna to just go outside and cut off all the parts that don't work. 160 meters (or 600 meters) doesn't lend itself to that simplicity - if nothing else because of size.
>>> 
>>> 73,
>>> 
>>> Bill  KU8H
>>> _________________
>>> Topband Reflector
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>> Topband Reflector
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