HF Radio propagation table

[MicHughV]

Interestingly, as you most likely know, most sailboat HF "antenna's" are made up using an insulated backstay. Because the backstay slopes forward, I've found that the direction my boat is heading, affects the range I can send and receive.

My advice, join a local ham club, they will likely be able to fix you up with a freq table.

[Phillip]

Originally Posted by GILow

Hi all,

I used to have a nice little table that gave an approximate guide to HF frequency vs propagation for day and night.

I misplaced both the electronic and paper copies, and now my Google skills are failing me.

Does anyone have a link to a simple table, something along the lines of...

Frequency Day Range Night Range.
3 MHz x miles to y miles a miles to b miles
4 MHz i miles to j miles

etc etc.

Yes, I know there are some really accurate online tools out there to give very precise predictions, but I just need something as a general guide that can be printed out and left with the radio books for those times when there is no internet access.

Matt

Here is a link: https://www.offshoreblue.com/comms/hf-intro.php
There is a nice table there.

[S/V Illusion]

Originally Posted by MicHughV

Interestingly, as you most likely know, most sailboat HF "antenna's" are made up using an insulated backstay. Because the backstay slopes forward, I've found that the direction my boat is heading, affects the range I can send and receive.

My advice, join a local ham club, they will likely be able to fix you up with a freq table.

Actually, the radiation pattern of a ‘sloper’ such as you describe is toward the back (toward the stern). There are numerous modeling programs demonstrating that.

[Phillip]

https://www.offshoreblue.com/comms/hf-intro.php

[MicHughV]

yes, that is exactly what I meant. interestingly, my first boat was a ketch, the split backstay of the main mast came within inches of the mizzen shrouds, so I was reluctant to use the main backstay as an antenna, so I rigged a pvc"pole" on the stern about 8' high, and started my antenna from there to the top of the mizzen mast and then continued it on the main mast, but it was not an ideal situation and eventually clipped the length between masts, using only the run from the pvc pole to the top of the mizzen, barely long enuff for an end fed long wire, but it worked fine, but was definitely sensitive to boat travel direction and how much I was heeled over. I had considered a fiberglass whip antenna, but could not see that working in rough seas, as it would be moving all over the place. my next boats were all sloop rigged, so all had the insulated backstay.
I've know some sailors to hoist a dipole antenna, when wanting to use the HF radio, but I have no experience with these on a boat.
It does make a difference knowing if the receiving party is to the east or west of you, or north or south, but in most cases an end fed long wire seemed to do an adequate job.

[GILow]

Originally Posted by Phillip

Here is a link: https://www.offshoreblue.com/comms/hf-intro.php
There is a nice table there.

Thank you Phillip. And I note that they go to some effort to point out that the table is only a starting point. Which I am happy with. It was exactly this sort of starting point that I was looking for.

Edit: Actually, there looks to be some good reading on that page.

[Mike Burch]

Propagation varies tremendously from hour to hour, day to day, season to season, and (importantly) year to year of the eleven-year sunspot cycle. Right now we are just coming off the bottom of a sunspot minimum, and HF propagation is beginning to improve, though it's still rubbishy.

Just call the station you want on its highest frequency, and if that produces no response, go one frequency lower. Rinse and repeat until you get an answer.

[coopec43]

Originally Posted by Mike Burch

Propagation varies tremendously from hour to hour, day to day, season to season, and (importantly) year to year of the eleven-year sunspot cycle. Right now we are just coming off the bottom of a sunspot minimum, and HF propagation is beginning to improve, though it's still rubbishy.

Just call the station you want on its highest frequency, and if that produces no response, go one frequency lower. Rinse and repeat until you get an answer.

I couldn't agree more!

I lived on Nauru Island (Central Pacific) and often used to phone home. At that time the telephone service relied on a radio link and as a result was often inoperable.

All the theory in the world is merely anecdotal.

[MicHughV]

I think the whole thing about Ham radio is that it gives the " tinkerer" an opportunity to come up with different ways to connect. Back in the day, I was part of a Ham Club, and every once in a while, we would trek off to some farmland in the woods and assemble a dozen different antenna's of every possible description...some were real doozies....dipoles that stretched from one end of a field to the other, etc...even had a helium balloon drag up a long wire and other contraptions...many of these were connected to a radio via a selector switch...so we could instantly tell which antenna was producing the best run for the money.
But, different frequencies and different times of the day, not only for us, but also those in other countries, favored different installation.
There was...and is.... no one size fits all. That is all part of the Ham fraternity....experimentation.

I can definitely recommend joining an area Ham Club. You are likely to meet some very knowledgable expert radio people who will be only to willing to set up a station for you on your boat.

[olivierlc]

https://www.solarham.net/

[ka4wja]

Matt,
Sorry, I've been tied up with some family matters....and only have a couple minutes...
And, while you've gotten a couple of charts posted here that will help....I'd actually like to help you even more....

So...
Matt et al,


Up front, please understand that I've been studying radiowave propagation and antenna system design (and RF engineering) for about 50 years now, and have been teaching these subjects to my fellow hams (and sailors) for almost 45 years....so, my first piece of advice for novices is:

Don't over-think it, just understand the basics....and that means just that...."understand" the basics (and the rest will come easily), just like nobody needs a "chart" or calculator to add 2 + 2, the basics of HF Radiowave Propagation should be easy to remember, if they're explained correctly.
So....

So, while I've written in detail about this in the past, and if you watch some of my videos you'll see this not just discussed, but actual real-world practical / live operations showing exactly how various frequencies are used for different ranges at different times of the day....but, the real down-home "basics" are pretty easy, and I do mention them multiple times in a couple videos....

And, here they are:


1) The higher the sun, the higher the HF frequency you use....the lower the sun, the lower frequencies are used....{fyi, nighttime the sun is lower....in this context, it's lowest at midnight thru dawn}

The longer the distance you need to communicate, the higher the frequency you use....the shorter the distance the lower the frequencies are used.


{After the two sentences in #1 above, these next two "rules of thumb" should be remembered....just remembering these 3 "basics" will go a loooonnng way, and should eliminate the need for any chart or table, for you}



2) I call this the "hundreds and thousands rule"....which is surprisingly accurate for daytime ranges....for nighttime, just use the same rule, and then move DOWN one or two frequency bands....and you're good-to-go!

The rules are technically "one hundred", "many hundreds", and "up-to one thousand"....{but, just use the very basics and just say, it's a "hundreds rule", and you'll be fine!}


For the most cruisers using most of the HF bands (particularly the HF lower HF bands....those with single-digit Mhz numbers, like 2mhz, 4mhz, 6mhz, and 8mhz; and the 1.8mhz, 3.6mhz, and 7mhz ham radio bands), just add 100 to the their mhz number to get their "average" maximum range...

For the higher HF bands of 12mhz, 16mhz, etc., you add many hundreds (or up-to one thousand)...

4mhz ~ = 400 miles max daytime (nighttime move down one band)
6mhz ~ = 600 miles max daytime (nighttime move down one band)
8mhz ~ = 800 miles max daytime (nighttime move down 1 or 2 bands)
12mhz ~ = 1200 to 6000 max daytime (nighttime move down 1 or 2 bands)
16mhz ~ = 1600 to 8000 max daytime (nighttime move down 1 or 2 bands)
Etc....etc...etc...


3) Always use the highest frequency band that allows communications to occur, for that distance and time of day.....

(remember that the "hundreds" rule is for daytime....nighttime, just moved down one or two bands, for the same range!)




I've been teaching these 3 rules above for 45 years now, and they actually work!

Learn 'em, Live 'em, Love 'em....and they work....no propagation chart needed!
(fyi, the subtleties and vagaries of HF radiowave propagation come with more study and experience....but they aren't included in any "propagation chart" either....so, just learn/remember these 3 simple rules, and you're good-to-go!)



But, fyi, these days I also add a rule number 4....which technically isn't a propagation rule, but is dammed important!



4) Ridding your boat of RFI (received RFI) will actually allow you to better use the HF radio! This is a very important rule to remember, and you won't find it on any "propagation table"!


So, I do hope this helps? If not, please watch the videos and read the stickies above, 'cuz all your questions are answered in either or both....



5) And, finally....
Here are links to some of the videos that should help as well...


Maritime HF Comms
(the first two videos here discuss HF Radiowave Propagation and Freq/Channel Choice vs. range covered, and the "rules-of-thumb" that I wrote above, etc....and video #20, shows real-world use of the "rules" highlighted above, that can be done by anyone / any layperson, within minutes of walking on-board....have a look at them!)

https://www.youtube.com/watch?v=fMTW...ZDo_Jk3NB_Bt1y

HF-DSC Comms

https://www.youtube.com/watch?v=D4PO...ga2zYuPozhUXZX

Fair winds...

John

P.S. Hope to have more time later this weekend, to help more?

[GILow]

Thanks John, those rules sound neat and helpful.

[ka4wja]

Matt,
You're welcome.

Originally Posted by GILow

Thanks John, those rules sound neat and helpful.

Yep....higher-the-sun, higher-the-freq....multiply 100 or more to the freq, to get max daytime range....always use highest freq possible for the range / time-of-day....

If radio users commit those to memory, things get easier...



BTW, not sure why the Youtube Playlist link didn't post correctly?
So, going to try again...

Check out the Playlists here....
Look for "Maritime HF Comms"
https://www.youtube.com/user/captain...able_polymer=1


(Check out video #1 and #2, and #20...the first two videos here discuss HF Radiowave Propagation and Freq/Channel Choice vs. range covered, and the "rules-of-thumb" that I wrote above, etc....and video #20, shows real-world use of the "rules" highlighted above, that can be done by anyone / any layperson, within minutes of walking on-board)


Fair winds.

John