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Author Topic: "Annual" Propagation (?)  (Read 4200 times)

« on: January 28, 2009, 09:34:26 AM »

Its funny, but every year since 2001, I have heard a few entities where I could only hear and work them in a one week span at the same time of the year.

I have only heard Togo and Gabon almost to the day in March every year on 30M or 40M - and usually just after sundown, and Ethiopia and Bahrain only in July after sundown - on 20M.

March would suggest vernal equinox, and July would be near mid summer.

Anyone else experience this sort of thing?

Posts: 2995

« Reply #1 on: January 28, 2009, 03:19:35 PM »

I seldom hear Singapore here in St. Louis; however I have logged several 40m QSO's with 9V's within a week or so of the Winter solstice, when my sunset closely matched sunrise at the other end.
Chuck  NI0C  

Posts: 4283


« Reply #2 on: January 28, 2009, 03:45:18 PM »

Sure like there is typical annual propagation around the two equinoxes.

« Reply #3 on: January 28, 2009, 03:55:55 PM »


Yes, the March QSO(s) point to the vernal equinox, but what do you think about the midsummer QSO(s)?

Posts: 2527

« Reply #4 on: January 28, 2009, 04:20:40 PM »

Sounds like you are enjoying playin radio.

What antenna are you using?

I used to have great fun playing long path around sunrise here, throughout the year on 20.  From here slightly off VK over East part of Africa thru the middle East into the UK.

During the winter, I'd have both long and short path to VU after sunset here, but not during the summer.

You can try looking at programs showing day light and darkness around the world and play with different dates and times.

Best from Tucson


« Reply #5 on: January 28, 2009, 06:41:33 PM »

I have a set of three 2 element K1WA arrays - for 40, 30 and 20M. The F/B is about 20 db, and gain about 4.1 db.

For 160M I have a "T" antenna up 60 feet with 60 radials and it can also be switched to be a ladder line fed end loaded (coil) doublet. It uses an SGC auto tuner in either case. Oh - I also have a K9AY lowband receiving antenna (from Array Solutions) - and that is one heck of a great antenna on 160 and 80M.

For laughs, I might put up my "other" all time favorite wire antenna - a Bruce Array - on 40M - which is my favorite band. 200 watts - no amp.
I worked / confirmed 322 total since 2001 and 301 were with 200 watts or less. (Had an amp for 2 years - but hardly used it - only for really tough one's where the pileups were murder).

Posts: 2086

« Reply #6 on: January 29, 2009, 06:31:58 AM »

Propagation shifts as the world tilts on it axis especially Noticeable at solar minimum. Long path and short path switch as the propagation moves from polar to equatorial. Signals from Africa and the Middle East are strongest for me between the middle of June and July, while signals from Asia and the Pacific are strongest from the middle of November and December. Also a part of the equation is the position and effect of the grayline propagator. These effects are not nearly as apparent during solar maximum. Good DX!

73 de Lindy

« Reply #7 on: January 29, 2009, 06:56:48 AM »

I remember getting up every morning a few years back - I think in 2004 - 2005, and I was able to get DXCC on 40M and 30M in one month - centered around January. Every morning, EU and the Middle East pounded in on Long Path. At the time I had 200 watts and a 24' short hatted vertical dipole.

I remember working TO4E on 30M with an S9 +20 using that same antenna, and even working the 3B7 DX-pedition from my van - with an AH-4 and whip antenna with 100 watts from a parking lot near Lake Tahoe. And the Kerguelin "Penguins" pounding in on 40 and 30M as well.

Morning grey line has always been my favorite - especially 40 and 30M CW. That's where little pistols can get their band - mode fills in.

I think in the last year or more, the MUF has been so low - because 160M many times sounds like 40 or 80M, and 40M is just on the edge.

I guess this is why at every point in the sunspot cycle - there is still DX to work. Its a fun hobby because you can come up with probabilities and forecasts - but there is still the element of surprise. Especially with grey line.

« Reply #8 on: February 02, 2009, 09:54:48 AM »


Here is the answer to the question regarding why propagation might be affected late July (I already knew why propagation was affected during the equinoxes - with the day and nights being about equal length):

There are 4 dates called "cross quarter dates" - and they are about mid way between a solstice and an equinox:

1) Groundhog day (Feb. 2nd)
2) May Day (May 1st)
3) Lammas Day (Aug. 1st)
4) Halloween (Oct. 31st)

Space says that these are "astronomically significant" days, and so I could imagine that propagation would be affected during any change in the grey line - as it shifts seasonally. Since the greyline happens before and after sunrise and sunset, very interesting things can happen.

I remember a few years back - propagation on 80 and 40M changed dramatically during the latter half of August - we were hearing DX to the East of us 2 hours before sunset. We were a little more than halfway between summer solstice and the autumnal equinox.

I think this variation - with or without sunspots really makes ham radio exciting. there enough variables that keep us all believing in the magic.
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