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[Articles Home]  [Add Article]  

Black Sky

from John Wendt, WA6BFH on June 18, 2005
View comments about this article!

Black Sky
By John Wendt, WA6BFH

The title is a concept reference common to radio astronomers. Unlike optical astronomers, radio astronomers do not have to wait for the dark sky of evening. For radio astronomy, with its comparative lack of sensitivity {over bandwidth} the sky is always black! For VHF/UHF DX’ers, this is also true, sort of!

For them the sky is always gray, it always contains some amount of atmospheric noise. At a wavelength of 6 Meters this atmospheric noise level is pretty high, and the sky is bright gray, almost sparkly. Over much of the higher VHF and UHF spectrum, and at about 3 KiloHertz receiver bandpass or less, the sky is very dark and almost black. With that consideration, and that at the energy levels pursuant to these very high frequencies, VHF energy will pierce the atmosphere -- except for certain anomalies of nature.

The late great Ross Hull W1AL first noted this just prior to World War 2. Using antenna systems of very high gain, sensitive receivers, and powerful transmitters at a frequency of 112 MHz, reliable communication was maintained on an extended over the horizon path. While considerable fading of signals was noted, these signals always maintained themselves at well above the signal levels as they were predicted by the “Smooth Sphere theory“ of Van der Pol and Bremmer. Ross Hull’s studies lead to development of theory of Tropospheric Ducting of VHF signals and was credited as “one of the truly outstanding examples of scientific achievement by an amateur in any field of human endeavor.”

This sort of signal propagation occurs when a large area or mass of cold or cool air is over-run by a warmer mass of air. This phenomena provides the primary mechanism for this signal bending or ducting. If these air mass fronts are large enough they will support VHF communication up to several hundred miles. The ducts or barriers formed by such air masses provide the first or lowest elevation barriers that re-direct VHF signals that would otherwise venture into space.

Sporadic E-layer VHF signal “skip” is the next mechanism that bends or refracts signals at these frequencies from entering outer space. The E-layer of the ionosphere resides at about 85 miles above the Earth. While it is known that disturbances of the upper atmosphere by high altitude storms is one primary cause of E-layer ionization, all mechanisms for this phenomena have yet to be discovered. VHF Ham’s are well aware though that such sporadic E-layer enhancement is not limited to the months of spring, when these high altitude storms provide showers for the mid-west of our country. Recent E-layer activity this last March provided sufficient ionization to allow signals as high as 222 MHz to be refracted to Earth!

Another not as common mechanism of VHF signal refraction is Auroral skip. When high energy solar flares occur, the D-layer of the ionosphere can be energized. This D-layer ionization absorbs signals in the MF (300 KHz to 3000 KHz.) and HF (3 MHz to 30 MHz) radio spectrum. This ionization while effectively ‘shutting down’ these lower frequencies, will actually allow for signal propagation of 50 MHz, and sometimes higher. While it has been many years since I have heard or worked such Auroral Skip at the low latitudes of Southern California, I have heard this eery and phase distorted form of signal propagation in the days when simple Amplitude Modulation with carrier was the order of the day on 6 Meters!

Known quite commonly to most Ham radio operators is F-layer signal propagation. While this mechanism is most prominent at 11 year solar peaks, and provides easy and long signal paths for the HF spectrum, it will also allow use on 50 MHz. When this occurs near the peak of this 11 year cycle, the M.U.F. or Maximum Usable Frequency will reach the 6 Meter band. This was most strongly observed during solar cycle 19 with a peak of the MUF in about 1958. In 1978 at cycle peak 21 the signal skip and DX or Distant Communication was also pretty good, as was cycle 22. Other peaks have been less dramatic but, still are notable over the waning years nearer the bottom of these cycles. Many Ham’s are enthusiastic about the next peak to come still several years hence!

Another mechanism of VHF signal propagation is Trans-equatorial skip. This is rare and fleeting in the part of the country where I live but, for folks in more southern clines can provide very exciting potential. When it does occur it will provide for MUF’s at about 1.5 times the typical daytime numbers. A few years ago I did work signals into South America where this may have been a supporting mechanism. It has though for me been so rare, that it is not a mechanism that I actively pursue. If we enjoy a high level ‘F-season’ in a few more years “TE” will be something to also possibly count on!

Meteor scatter is the next method of VHF signal propagation. At regular intervals when, major meteor showers occur, 50 MHz signals will be as strong at distances over thousands of miles, as they are for local signals. These very strong signals will sustain themselves at a constant level for 10 to 15 minutes. Within the next following minutes these signals will be noted as slowly fading. Then at about 20 minutes, the signal level will dip, rise, and then quickly fade away. All of this occurs over the time period as the Earth rotates below the ionized trail of the meteors of this sort of storm or shower. Such storms occur on a predictable time frame as these meteors orbit our galaxy. There are stronger and lesser such showers but, they are always exciting to observe on the radio, and are sometimes even visible to the naked eye!

These are the best known mechanisms that affect the VHF radio spectrum. There are other aspects of physics that effect higher frequency realms at the UHF (300 to 3000 Mc.) and SHF (3000 MHz to 300 GHz). I have little experience with these realms, and only limited knowledge. It is equally enjoyable to me though to follow the pursuits of other Ham’s who are active in this spectrum and note the mechanisms that they utilize to speak over hundreds of miles and more!

Beyond this is the realm of the radio astronomers! The first of these was a Ham by the name of Grote Reber. In 1937 he built a 31 foot diameter parabolic radio reflector. He designed radio equipment to be used with this ‘dish’ for the 9 cm wavelength band, some 3 times lower in frequency than our most popular microwave Ham band today! Even still, to make vacuum tubes of the day work as high as 3000 MHz, at this relative “DC” frequency was quite a feat. That though is the frequency that he determined Max Planck’s “Blackbody law” could be resolved. With that goal in mind, he set to work. This is what Ham’s have always done. They move to the areas where knowledge is yet to be gained, where the nature of the radio spectrum is more challenging and less predictable. Mr. Reber’s telescope can now be found at the headquarters of the National Radio Astronomic Observatories.

Member Comments:
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Hamsexy  
by NN8Y on June 18, 2005 Mail this to a friend!
So, what the heck IS hamsexy all about?

I saw their booth, saw nothing about amateur radio there, and found nothing sexy about it. There was nothing of interest there, but I did pick up a card.

I checked out the website, and it seems like it is anti-ham if anything. I don't see an reason for the attraction, except that, like the evening news, they purposely create controversy which feeds curiosity that attracts attention. It worked on me.

Then I suppose a particular type of person will find something interesting about it and go back. Makes you go hmmm.

73
Rob
NN8Y
 
RE: Hamsexy  
by K0BG on June 18, 2005 Mail this to a friend!
Enlightening! However, there are more than just a few amateurs who have been credited with discoveries of the magnitude of those you mentioned. For the most part, the discoveries weren't relatable to amateur radio, but some were. John Kraus', W8JK, Big Ear comes to mind, and I am sure there are many, many more. All of this proves the old adage that fame is fleeting.

Alan, KØBG
www.k0bg.com
 
Just go Get the ARRL VHF Manual  
by K2WH on June 18, 2005 Mail this to a friend!
Interesting posting about VHF propagation. If others want to learn about this, especially the techs among us, go get a copy of the ARRL VHF Manual. I have had one since 1973, and describes in detail all you have said.

K2WH
 
RE: Just go Get the ARRL VHF Manual  
by KB1EVZ on June 18, 2005 Mail this to a friend!
NN8Y, a better question is, "What does your post have to do with VHF propagation?"
 
RE: Just go Get the ARRL VHF Manual  
by NN8Y on June 18, 2005 Mail this to a friend!
Heck, I don't know, I didn't read the article.

I wouldn't read anything written by the guy who posted the following bizarre rant, I wouldn't trust the anything they said to be accurate:

"SOME here read whatever into my words that was pushing either their psychosis, or neurosis.

"I�m guessing that my words �pushed the button� of a few folks that are just victocrats! They MIGHT also be amongst a certain elite group of ham�s who show up at public ham meetings wearing dirty or completely inappropriate clothing, thusly displaying their lack of dignity, and thereby denigrating those that have put such a meeting together. They MAY also be amongst a group that finds bathing to be just too much trouble. They also might NOT!"

I'll get my learnin' from the ARRL manuals, thanks.
 
Black Sky  
by WB2AMU on June 18, 2005 Mail this to a friend!
Thanks to the author for providing summary of each of the major propagation modes on VHF. There are two books out there for those who wish to see more details on each of these modes in terms of when they occur and descriptive diagram. These books are SIX METERS, A GUIDE TO MAGIC BAND (Worldradio Books) and VHF PROPAGATION, A PRACTICAL GUIDE FOR RADIO AMATEURS (CQ Magazine books). The first book was written by me and the second was co-written by me and Gordon West, WB6NOA. There is even an audio CD that we made for this book that has samples of the different modes of propagation. Signals that are distorted by the aurora mode are the most interesting on the amateur radio bands. I might add that both of these books show the graphical desciption of the modes - for example the backscatter method of aurora, the forward reflection of Sporadic-E and the extension in the F region over the equator of TEP. If interested in these books, please contact me via e-mail.
 
RE: Hamsexy  
by K8MHZ on June 18, 2005 Mail this to a friend!
Rob,

Write to them and ask them.

I do just that on occasion. I get decent replies when I do.

73,

Mark K8MHZ
 
RE: Hamsexy  
by WA6BFH on June 18, 2005 Mail this to a friend!
Gee, I'm glad you guys liked the article! If it is being compared or contrasted against "Hamsxy", I guess I'm in good company huh?

I think I'm gonna get me one of those FT-101's. I can put that baby on 11 Meters, and change the tank circuit on my Gonset (four 811's) to work there too!

To heck with science, and serious interests in Ham radio etc. Who cares about working all states and a bunch of countries on 6 Meters anyway? I will just get on 11 Meters and talk like a moron, drink lots of beer, and work on more important things like being heard on my neighbors telephones and every other audio device in their houses!

Catch ya later good buddies, and good numbers to ya!
 
Black Sky  
by N5EIL on June 18, 2005 Mail this to a friend!
I thought it was a well written article for those who don't have much experience with weak signal VHF/UHF, and could add some incentive to get them in the VHF+ world.

I personally love weak signal VHF+, and the challenges it has.

73
N5EIL, Neil
 
RE: Black Sky  
by W6TH on June 18, 2005 Mail this to a friend!
.

Very nice writeup John, but nothing new to me. Played with it on 56 megs, was easy then as we doubled from 28 Megs (10 to 5 meters).

You can try for yourself, called backscatter and use a receiver with a very fast recovery time. Use a pulse rate of 10 or 20 and look for the salient echo on a scope.

Remember the Woody Wood Pecker? That was me as a operator and our group of operators.

Ham radio is not the only way to enjoy RF.

73, W6TH.
.:
 
RE: Black Sky  
by GHOSTRIDERHF on June 18, 2005 Mail this to a friend!
WA6BFH --

wow -- another copied and pasted article that could have ben summed up in one sentence...

but instead you feel that you have to write 20000 words to get over something you could have in 100 -- oh and by the way -- once again you missed your own point...

but then again -- it could be worse -- you could actually be on the air (once you get a radio) instead of spending all your time on the net




.
 
RE: Black Sky  
by W6TH on June 18, 2005 Mail this to a friend!
.

Go after him John, He loves you.
.:
 
Black Sky  
by VE3VYZ on June 18, 2005 Mail this to a friend!
You forgot to mention EME, the coolest VHF DX mode of all!
 
RE: Hamsexy  
by NN8Y on June 19, 2005 Mail this to a friend!
<Who cares about working all states and a bunch of countries on 6 Meters anyway? I will just get on 11 Meters and talk like a moron, drink lots of beer, and work on more important things like being heard on my neighbors telephones and every other audio device in their houses!

Catch ya later good buddies, and good numbers to ya!>

Gotta hand it to ya, BFH, you never run out of new ways to put others down. Let's see now, on the growing list for this week is:

Disabled people
Those who are "hygenically challenged"
CB'ers
Those who don't always spell every word perfectly

Maybe you should start a movement to just exterminate all those who aren't as good as you, BFH. But, that's been done before, in many places, by many people, the most infamous one being a fellow named Adolph.

I'll let it go, now, BFH. I just have no use for people that put others down, and especially those that kick others when they're down, and I won't ignore it.
 
RE: Black Sky  
by GHOSTBUSTER on June 19, 2005 Mail this to a friend!
I see Goatdung has taken some time off from his job at McDonalds and his CB set to ad his usual insightful and informed commentary to someone's article. Funny, I've never seen an article or a productive forum post on any subject from him.
 
RE: Black Sky  
by N8BOA on June 19, 2005 Mail this to a friend!
Great Job Hey bfh "Never say you know it all, else you will be right, you know all that you will ever know"
PSC
 
RE: Black Sky  
by WA6BFH on June 19, 2005 Mail this to a friend!
Ok there NN8Y! I think though that you respond with a little too much vehemence in you’re your thoughts. It lets others know that at least some of my comments or thoughts must have hit a little close to home. Oh, I think you missed those ‘on the list’ that can’t seem to dress appropriately either. I will take your ideas to heart though.

I did receive a very nice direct e-mail from a new Ham, awaiting a new callsign. So, I’m hoping that soon we will have a new VHF DX’er on the bands! It is just such a cool thing in any case that Ham radio is such a broad field of nearly 24,000 MHz of spectrum to play with and explore. So many wavelength bands, and so many modes! You can never get bored, no matter where your interests are at any given point in time!

Well, I am monitoring 50.125 MHz, and also a 1200 MHz machine; maybe I might catch some of you on the bands?

73! de John
 
RE: Black Sky  
by KA4KOE on June 19, 2005 Mail this to a friend!
Okay, here is the inevitable question....
what does this all have to do with its application vis a vis, the fan dipole?
 
RE: Black Sky  
by K8MHZ on June 19, 2005 Mail this to a friend!
John,

I think that if you had written about the active ingredients in Snappy the Wonder Poodles’s Magic MoPed Oil the thread would be exactly in the same place that it is now.

Thanks for taking the time to write a nice article about propagation techniques in the upper bands that may have escaped some of us.

I am jealous of the fact that I was not the first to ask about the application of a fan dipole to your observations.

The early worm gets the bird….

73,

Mark K8MHZ
 
RE: Black Sky  
by WA6BFH on June 19, 2005 Mail this to a friend!
And Campbell wins the U.S. Open (-1), with Tiger Woods work’n it to finish 2nd, and coming from a +4 to go to even, and finish +2

Maybe they will try ham radio, when they tire of golf?
 
RE: Black Sky  
by GHOSTRIDERHF on June 19, 2005 Mail this to a friend!
WA6BFH

Isnt is great that not only do you try to dominate the forums by writing fairy tales that make no electronic sense but then you have to dominate everyones reply .... why do you feel it neccessary to comment on every answer someone repsons to...

your not that respected or smart to pull that off

and .. the sad part is that you are wrong most of the time,,,,,
 
RE: Black Sky  
by GHOSTBUSTER on June 19, 2005 Mail this to a friend!
I see Goatdung has taken some time off from his job at McDonalds and his CB set to add his usual insightful and informed commentary to someone's article. Funny, I've never seen an article or a productive forum post on any subject from him.

Yeah right.....a CB'er like Goatherder would know what makes "electronc sense".


 
RE: Black Sky  
by W6TH on June 19, 2005 Mail this to a friend!
.

Just imagine that governments have failed for over 5000 years, Bush is a bureaucrat (An official of a bureaucracy) and never will be a soldier, Kerry a asshat, Clinton a cradle robber, congress a den of thieves and lastly, EHAM brings out the best of mankind.

73 Mahatma Gandi.
.:
 
RE: Black Sky  
by WA6BFH on June 19, 2005 Mail this to a friend!
VE3VYZ, I have never worked “EME” myself but, you are right, it is cool -- and I hope to soon!

73! de John
 
RE: Black Sky  
by GHOSTRIDERHF on June 19, 2005 Mail this to a friend!
Just in case anyone has missed it on the previous threads -- GHOSTBUSTER AND WA6BFH are both the same person...

now thats pretty pathetic in and of itself...

the sad part is when he has to pick an alternate identity so he can find someone to finally agree with him...

PS -- I was happy to see that WA6BFH made Hamsexy.com ... prety funny article there about him...
 
RE: Black Sky  
by JGALT on June 19, 2005 Mail this to a friend!
My thoughts are that if WA6BFH wanted, or thought that he might fancy an alternate identity, he would be a bit more creative!
 
Jihad Against BFH  
by KA4KOE on June 20, 2005 Mail this to a friend!
"Just in case anyone has missed it on the previous threads -- GHOSTBUSTER AND WA6BFH are both the same person..."

--No proof, you're raving again in this one man jihad you have against BFH.

"now thats pretty pathetic in and of itself..."

--kinda like the pot calling the kettle black, don't you think?

"the sad part is when he has to pick an alternate identity so he can find someone to finally agree with him..."

--I like BFH, so do several other people that come to mind. And who, agrees with you? Raise your hands, kids. No takers? Hmmmmm. Not surprised at all at all.

"PS -- I was happy to see that WA6BFH made Hamsexy.com ... prety funny article there about him..."

--Checked and did a search on their site. Nothing found. Perhaps you, as a suspected member of their editorial staff, have some inside knowledge of an upcoming "expose"???

Sadly, these rants grow tiresome. Need to up that dosage, dude.

Feeleep
 
RE: Jihad Against BFH  
by GHOSTBUSTER on June 20, 2005 Mail this to a friend!
Ol' goatpoophf is a little scared now because someone knows his identity. It's even enough to keep him off 11 meters for awhile.

Busted!
 
RE: Black Sky  
by WB2WIK on June 20, 2005 Mail this to a friend!

>RE: Black Sky Reply
by KA4KOE on June 19, 2005 Mail this to a friend!
Okay, here is the inevitable question....
what does this all have to do with its application vis a vis, the fan dipole?<

[I was wonder that, also. I did try a Fanned Eyepole on six meters one, though.]

Nice writeup, John. Must be killing time waiting for six to open, since it's been kind of crappy the past week or so now...

I saw numerous posts about 1x and 2x Es on various clusters, it was all east of the Rockies, and mostly east of the Mississippi. Foiled again, for us guys out west.

WB2WIK/6


 
RE: Black Sky  
by WA6BFH on June 20, 2005 Mail this to a friend!


Philip and Steve, thanks for the nice thoughts and comments! I really do enjoy e-Ham! Many folks have been inclined to write me direct e-mails pursuant to this article. If they feel up to it, I would encourage them to post a statement here too. I am getting a bit tired of this free-band’er dweeb, although probably giving him ANY recognition will serve to feed his warped ego, and we will likely hear even more of his demented ravings.

I had recently told Clinton that I was running dry on subject ideas for his page, and that I did not anticipate posting anything else soon. Yesterday though I was once again inspired! Below are some rough excerpts from this piece. I will have to think it over for a couple days, and hone and polish the product on its finer points. You might find even this minimal preview of some interest though?


......................................

Young Minds & the Frontal Lobe

Recent studies indicate that younger folks, at their mid-teens, show an inclination that their brain growth -- or the frontal lobe of their brain, is not yet fully developed -- but is ravenous for input. ……

My general thoughts were when I heard of this, that this analysis was framed in the context of how these young folks relate to video games -- a motor-memory skill --, yet a skill that does impart conceptual ideas or notions. Now we have known for a long time that our kids are doing pretty poorly in terms of studies in Math, the Sciences, and many scholastic subjects that will serve them better than being really great at video games! So, what do the parents of these kids think about this, I wonder? Do they think “Gee, I wish I could get my kid turned on to something that would inspire him/her to do better in school? Are there any subjects or activities that promote science and math, yet are fun in their general pursuit -- something that might hold my kids interest?”

Do these parents even know about Ham radio? Or do they like many within the lay public, think that CB is Ham radio? Should we tell them that Ham radio -- as an avocation pursuit -- basically owns 23,471 MHz of radio spectrum? That we have space communication satellites, and have on many occasions had scheduled programs that allow Ham radio operators to talk to astronauts on the Space Shuttle? .......



Well guys, you get the idea, and yes this does give me something to do as I monitor 50.125 MHz!

73! Think E-layer ionization! de John
 
RE: Black Sky  
by W6TH on June 20, 2005 Mail this to a friend!
.

For better schooling, I have found a few who are now dropping out of these government controlled schools and using the home study schooling and the private schooling.

I now know of two who have gone along with the home schooling and are now ready to enter college. This shows good promise.

As you know, we very old old timers were self taught and never heard the word elmer, this also shows promise. I for myself have learned more about engineering than just what information I have been taught in college. If it were not for my wanting to learn more by advanced study on my own, I would not have been able to work for the past companies that I have.

The three R,s are very important and then should go for the subject the student is most interested in. In High school I majored in history and minored in industrial arts, yet I went for electrical engineering; strange for the change isn't it.

Government controlled schools are dumbing down the education of today and I noticed that the Constitution and Declaration of Independance is not of any importance any longer. The Constitution is just a scrap of paper today.

My first learning was NRI course, Grantham, then CREI all home study and finally college.

73 W6TH
.:
 
RE: Black Sky  
by N5EAT on June 20, 2005 Mail this to a friend!
I had forgotten the Woodpecker! What a memory jog that was..
 
Black Sky  
by KB1JCY on June 24, 2005 Mail this to a friend!
Bookmarked and x-posted to HamForum.

Nicely written yet gentle introduction to DX above 50 MHz. I think every Tech needs to know this stuff. Repeaters are the AOL Teen Chat of our hobby. Since this weekend is Field Day, I encourage everyone to try VHF operations. Especially if you are on the east coast US. Check this <a href="http://home.cogeco.ca/~dxinfo/tropo.html">report. Paris Hilton best described this weekend's tropo condtions when she said "That's hawt!"
 
RE: Black Sky  
by OLDFART13 on September 4, 2005 Mail this to a friend!
groups.yahoo.com/group/hamsexy
 
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