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[W4NKY]

Hi everyone,

I've been experimenting on 10m (mainly FT8) while I wait for an exam session to get my general.  While I've had quite a bit of success, I'm having trouble understanding the propagation patterns I'm seeing:

Last week I made quite a few contacts in the north east (NY, MA, NH) and SW (TX, LA) but almost no where else, which is odd because those locations are in the same direction as my end fed antenna and I was unable to make a single contact perpendicular to my antenna (which should be optimum).

Then today I made contacts in Brazil, Chile, and Argentina with higher SNR (-3 to Chile) than stations very close to me (-20 only 100 miles away and the best SNR in NA was -12).  Assuming this would be only a single hop otherwise I would expect to see other strong signal reports closer.

The ARRL manuals are little light on the science of propagation, if anyone knows of some better reading material I would appreciate the suggestions.

Thanks in advance!
Brad
 

[W9IQ]

An end fed antenna breaks up into multiple nodes as the frequency is increased. So it wouldn't be an unusual circumstance on 10 meters. What is the length of your main wire?

Also keep in mind that while all antennas have favorable gain in a particular direction, it doesn't mean that the antenna doesn't put out or receive a signal from less favorable directions. FT-8 allows communications under very weak signal to noise conditions so even a negative dBi gain from your antenna may facilitate communications.

- Glenn W9IQ

[W4NKY]

It's just a hair over 135ft (based on AB3AP's calculations) with a 64:1 balun it easily tunes 160-10m.

I understand the antenna gain, just a bit surprised at the inverse correlation... I expected there to be at least a slight correlation.

[W9IQ]

If you model the length of that antenna, plus the length of the counterpoise, you will find on 10 meters that there are lobes pointing nearly out of the ends of the wire.

The matching transformer (not a balun) is there for impedance matching. It has no effect on pattern.

- Glenn W9IQ

[W6RZ]

Last week I made quite a few contacts in the north east (NY, MA, NH) and SW (TX, LA) but almost no where else, which is odd because those locations are in the same direction as my end fed antenna and I was unable to make a single contact perpendicular to my antenna (which should be optimum).

The propagation mode for those contacts was Sporadic E. Sporadic E is caused by clouds of ionization at the height of the E-layer. Because the clouds are localized, the propagation will also be localized.

https://en.wikipedia.org/wiki/Sporadic_E_propagation

Then today I made contacts in Brazil, Chile, and Argentina with higher SNR (-3 to Chile) than stations very close to me (-20 only 100 miles away and the best SNR in NA was -12).  Assuming this would be only a single hop otherwise I would expect to see other strong signal reports close

On 10 meters, stations at 100 miles will not be propagating by the ionosphere. There is no hop. It will just be direct line of sight, with high attenuation.

[W4NKY]

That would make more sense... I need to learn 4nec2.

Transformer correct, so many examples online refer to it incorrectly as a balun.  (actually googled it before I sent my last because I didn't want to be incorrect, turns out the first listing calls it a balun)

All the way to SA is that a single hop or just a coincidence that no one was monitoring at the other hops?

[W6RZ]

All the way to SA is that a single hop or just a coincidence that no one was monitoring at the other hops?

The propagation mode for South America can be trans-equatorial propagation or TEP. With this mode, there's an ionosphere to ionosphere hop that makes for one really long hop.

[W6RZ]

More on TEP.

https://k9la.us/Trans-Equatorial_Propagation.pdf

Many other propagation articles.

https://k9la.us/

[W4NKY]

That's amazing material, thank you so much!

I also just found VOACAP, the visuals make a lot more sense (assuming I'm interpreting this map correctly):

https://imgur.com/HpRzOGv

[VE3WI]

For reading material you might try "Propagation & Radio Science" by Eric Nichols KL7AJ.  Easy to read & very informative.  Available in paper or Kindle ebook from ARRL or Amazon.
73
Dave, VE3WI

[KBKZ2105]

I will try to make this very simple.  Ham radio is like watching the weather in the morning.  They don't know you don't know it's just a semi educated guess. Think about what I just said and apply it to this hobby.

[W9FIB]

I will try to make this very simple.  Ham radio is like watching the weather in the morning.  They don't know you don't know it's just a semi educated guess. Think about what I just said and apply it to this hobby.

Sure.

You watch pigs fly as well?

[KBKZ2105]

What would be your advice Stan?

[W9FIB]

What would be your advice Stan?

Read up and learn. That is how most understand something. Many things in propagation have patterns derived by observations over the years and documented. One needs to learn the patterns, and the results will follow.

Far from being a guess if you understand the subject. Without learning, you won't understand. Without understanding, then it is a guess.

[AA6YQ]

This is the best book I've encountered on HF propagation:

https://store.cq-amateur-radio.com/shop/the-new-shortwave-propagation-handbook/

The book is out of print, but the CD is available:

https://store.cq-amateur-radio.com/shop/the-new-shortwave-propagation-handbook-on-cd/