Shortwave Radio Signal Paths - Ham Radio

[@sm6ehy816]

Thank you for addressing the issue. The common "hop" of signals does not occur so often that the propagation papers say. Around the Equator we have a ridge in the ionosphere that is acting as an important part in the propagation. Not only in directions E - W but also N - S (trans-equatorial path). The signals bounce more often between different points "in the same layer". We have a computer propagation program that addresses this, PROPLAB PRO. Here we can see how the actual signal path looks like; true "ray tracing". It somewhat comes to "where" in the ionosphere do you signal create the highest field strength. It is from this area the main refection occurs. For example, the path EU to KH6 on 160m. "All" textbooks say that the optimum time for a QSO is in mid December, via the Arctic. This path is heavily influenced by the "blotting paper" of the Aurora. I made many attempts to achieve a QSO with KH6 then, but only one way success. BUT at the latest opportunity in the winter season at the spring equinox I say a possibility for a QSO. I arranged that KH6CC at 800m ASL at BL20ha to be QRV (1986 before any computer predictions...). At the 1st try we had a 2 way QSO directly, and I could hear him consistently for 1.5 hours. We tried the next morning with the same effect. I had a phased vertical array at the time for 160m, and I had to point my front lobe towards the equator close to the Panama Canal. A great signal path bending of some 90 degrees azimuth also, in conjunction with rather HIGH take off angle. The program PROPLAB PRO later confirmed this path take off and azimuth bending effect. Radio signal bounces off the ground or sea water is VERY LOSSY in comparison with almost lossless reflection ionosphere inter-layer or layer to layer bounce. Good luck with Your "long haul" contacts on 7 MHz. 73 de Bjorn SM6EHY

[@watersstanton]

Interesting to read. I know that when I was first licensed back in 1960, working KH6 was a real milestone with that very familiar flutter on the KH6 signals - and that was AM in those days!

[@haraldlonn898]

Thanks for confirming what I suspected. There are many who think but few have proving measurements.

[@watersstanton]

You bet

[@peter-vk3acz]

Yes, expectations and reality, can be a different thing. During the pandemic when I wasn’t allowed to leave home and everything was closed anyway, I strung up an endfed antenna along 3 sides of my back fence no higher than 7 feet off the ground. Imagine my surprise when from VK I worked into Finland repeatedly on 40 metres! Go figure? Cheers, Peter, VK3ACZ

[@brianfields4479]

Thanks for sharing Peter, explaining exactly how we made contact not so long ago, and why many uk guys get through to me each evening long path. I have over my 38 years come to think, get a reasonable wire ant, my personal preference is a vertical, and hit the greyline correctly, and dx is always possible. Cheers zl3xdj.

[@watersstanton]

Great! Nice to hear from you. 73 Peter

[@ahheng6402]

I am now in my 50s & going back to my radio hobby that I used to enjoy when I am a teen in 80s thank you for explaining the truth of radio propagation. greetings from Malaysia

[@watersstanton]

Great to hear from Malaysia. I have had some great holidays out your way - when I was younger!

[@prabhakarv4193]

Very nice and interesting information. Thank you Sir

[@prabhakarv4193]

Very nice and informative. Thank you

[@Dan-56]

Peter, thanks for yet another great video 👍! One of the challenges I face when “Elmering” newer HAMs is to get them to see past the “theoretical” perfect antenna, and to experiment with antennas in their own locations, with as you noted lots of obstructions to the program driven antenna designs. Like you, one of my favorite reference books predates computer designs…..it’s a 1951 ARRL Handbook I picked up at a ham fest. It’s just amazing the amount of knowledge we had before we relied on computer driven “perfection” 😆!!! Keep up the good work you’re doing in helping to educate us all 👍! 73 de Dan WD4DB

[@watersstanton]

Hi Dan, Great to hear from you. Yes agreed. 73 Peter

[@philhayward8696]

Well, that has cleared up some dearly held myths. Thanks for that Peter, well presented. Cheers ZL2VTH

[@watersstanton]

Hi, nice to hear from ZL. 73 Peter.

[@kristhompson8112]

There is hope for us Kiwis after all . Will have to keep an ear out for ya @@watersstanton Regards and 73's Kris ZL1KJT

[@GordonHudson]

This is why a 3/4 wave vertical antenna on HF can often be better than a 5/8 wave, even though the 5/8 has a theoretical lower angle of radiation. I can remember when some TV antennas and amateur radio VHF beams were "jacked up" to get the lobes at a better angle. I remember someone who had a remote control actuator (before azimuth rotators were easily available) that allowed him to change the angle of his beam to peak a signal. It really did make a difference.

[@watersstanton]

Interesting. Many thanks.

[@CurtNovitsky]

Maybe hf refraction and double hops have some similiar characteristics of vhf /uhf ducting during temperature inversions ,and path horizontally for longer distances than we give it credit thanks agn

[@DarrenBainbridge]

The use of the term "cancelled out" is a bit misleading. There is some single/power being emitted at low angles; it's not 0, but definitely not ideal. The poor ground reflection described by the pseudo brewster effect is creating some deconstructive interference reducing the power of the single effectively received from low-angle transmissions. Single is still being emitted into the far field. This is effectively reducing the gain of the antenna at low angles. The illustration you use at 7:00 shows precisely this.

[@gertdejonge6050]

Nice one, Peter! Especially very useful for 'newer' HAM's, who like to learn more about this topic. I always watch your vids with a lot of pleasure. I'm still learning after being QRV for decades. Keep up the good work! Unfortunately I never had the pleasure of meeting you on the band(s), but I'm sure we will one day. From my QTH 40m has a nice hop towards Britain.... 😉 73 de Gert - PD0CT The Netherlands

[@watersstanton]

Great to hear from you Brian. Thanks for your support.

[@wonderingworld119]

You should do a video about 10m wire dipoles at some point, and how to make and tune them without an ATU just using an SWR meter. They are cheap to make, have directional properties, easy to put up half a wavelength, have a very low SWR meaning you don't need an ATU on that band, and will outperform antennas costing hundreds because they are actually resonant. At this time in the sunspot cycle they must the perfect project for working DX.

[@watersstanton]

Thanks for the suggestion.

[@davidwalle5025]

Great video keep them coming.

[@watersstanton]

Thanks, will do!

[@dandypoint]

I think you are only the second time I have ever found anyone on KZbin mention the Brewster angle! Congratulations! It’s a big deal with vertical antennas. Also I don’t think any of the computer models can really handle really low elevation angles. For one thing whoever is doing the modeling would have to get the ground part of the model correct in addition to the computer program being able to handle it. If you have a good pattern, what’s not talked about are the 3dB points. There is a peak angle but there is a range of angles from some number of degrees below to some number of degrees above that makes up the vertical beam width. Thank goodness for that because you never know what angle or angles you need. The height of the ionosphere is always changing up and down and the density is changing (which changes the MUF and critical frequencies). Not to mention that the signal is not reflected at a point but “bends” and sometimes is scattered to the side or even back towards the transmitting location. Good video. I have many of the old books also plus even though I have my University text book from when I studied “Radio Wave Propagation” I recently found a digital copy online free! Would you like a copy? 73, de N4DJ

[@watersstanton]

Many thanks. In one of the video clips I did mention “bend” but I think, when I rerecorded it, I missed it out. Bend rather than reflection is a more accurate description for the reason you mention. Yes, be good to get a link for the digital copy. My mail address is on QRZ. G3OJV. 73 Peter.

[@dandypoint]

@@watersstanton I will send it out now.

[@Team-fabulous]

Sometimes it doesn't pay to start reading too much into this topic. Like many hams I have a limited size back garden which restricts me to what type of antenna and what height I can go.. So like many hams I just stick up my verticals and a rotary dipole as high as I can and hypresto.. They appear to work as I can get into VK, the states and south America which makes me a very happy bunny but I'm quite happy with some inter G on 40 for a good old proper natter.. 73s

[@watersstanton]

Sounds like you are having fun.

[@wonderingworld119]

I have no idea at all why certain people push the 5 degree mentality, could be something with software saying their antennas are good at 5 degrees maybe and so maybe they push that mantra? I have no idea.

[@watersstanton]

Probably not far from the truth!

[@wonderingworld119]

A good test for people is to actually listen on their own radios to what the DX stations coming in are actually using. If you had a pound for everyone saying they were using a horizontal antenna and you gave a pound away for everyone you hear using a vertical, I reckon at the end of the week you would have enough money to build yourself an amazing horizontal antenna.

[@watersstanton]

Sounds about right - try it !

[@grandpaandlucas7054]

I made a 3 element yagi and at 25 feet I've been working japan long path on 21mhz with 200 watts with very good results. but i don't seem to have any decent dx on 7mhz.

[@Redbelly357]

Too many people blindly follow the software instead of doing a little experimentation. The software has it's place but it can't replace hands on.

[@watersstanton]

Agreed.

[@Roddy1965]

Pretty hard to dispute properly made measurements. You can, but it's a fool's game!

[@nickaxe771]

I have a horizontal doublet.....6mts above ground....less in parts.....58mts long....great for 160 to 10m....infarct I can tune 6mts on it and it does as well as my dedicated 1/4 was 6m horizontal.....crazy.... I love top band 160m.....if you listen to some of the old G3s.....to work top band your need your horizontal wire a 1/4 above the ground....so 40mts or 130ft..... I do really well on top band and get great sig reports.....I use Reverse Beacon Network to see how well I do.....at night on 160m I can work all points of Europe and into the well into the USSR.....so what was it the old G3s were saying. I do think there is a lot of toss talked about radio.....and still lots we dont know.....we cant see the radio waves can we.....yes field test have been done but there are still mysteries. I often wonder how many hops my sig just made to reach the West Coast USA.....Or Oz.....or Japan.....does anybody know????? Like I say.....lots still to understand about radio and prorogation.

[@watersstanton]

Well said - BTW i am an old G3 !

[@nickaxe771]

@@watersstanton Not all of course Peter. Generally the ones that resent new commers.

[@PedroskiClimb]

The suggestion that five degrees is optimal for DX is eroneous and based on overly simplistic ideas that don't take into account what happens to electromagnetic waves in the ionosphere. The best sources of information are research papers in the field of Over The Horizon Radar that use PHaRLAP ray tracing, a number of which are authored by Dr Manuel Cervera. Digging into these clearly shows that the assumption that five degrees elevation is optimal for HF DX is false. The optimal elevation is dependent upon ionospheric conditions, which are continually variable, at that time and the frequency. Often the low angles can produced the shortest hop distance. it's a fascinating subject, and it's a shame that most people seem to just go along with what they've heard. There is a lack of self-learning! 73 M3KXZ

[@watersstanton]

I agree and practical tests I have made underlines this point.