Radio Waves and Signal Polarisation HF, VHF and UHF

[@sean-sk]

polarization is one of many attributes that make antenna and radio theory so interesting

[@riaanzs1zarconradie291]

I love the flying saucer UFO with the antenna on top. 🤣 Just pulling your leg. This might explain why I sometimes get a station that changes from super loud to almost nothing in a single over. Either band conditions (but the change is too fast for that) or it might be shifts in polarization which accounts for the speed at which the changes in audio level and signal strength takes place. Sometimes 2 - 4 times in a single over. Thanks for the video. I remember seeing another video about drone antennas that mentioned up to a 40dB loss between vertical to horizontal polarization from remote to drone.

[@DXCommanderHQ]

40dB.. the extra 20dB MIGHT be fade due to distance.

[@jamescstanley5018]

Thanks Cal for clearing up the reason for the strange looking Yagis that look like a big coiled spring! I sort of guessed that they were something to do with polarisation, and now I know for sure! Great series acting as a reminder. As I intend to study for the next level up from my Foundation, this revision is handy, so useful that I am going to get the latest Foundation book to be bang up to date with the lower course as I expect there are some "new" things in there! Catch you on the air sometime, 73 Jim M7BXT

[@DXCommanderHQ]

FAB

[@Tblpeps]

Hi Cal, I love your little ditty videos explaining stuff....just the right amount of technical and plain talking.

[@DXCommanderHQ]

It's about all I can understand!

[@TheAppalachianWay]

Antennas and efficient feedline are more important than the new radio we are researching. Thank you for your effort

[@DXCommanderHQ]

Very true!

[@miketaylor6700]

A friend and I were making contact on 10m… we were cross polarized which cancelled our signal like you said.. by 20dB!! He was using 5w so I couldn’t hear him at all. Thanks for the great explanation!!!

[@YeshuamyKing53]

That's very similar to George Jetson's car! Great video! Thanks Cal!

[@DXCommanderHQ]

It is!

[@M7EUP]

Excellent video as always. Nice to refresh on the foundation stuff once in a while, especially as those of us studying towards intermediate will get the odd foundation question thrown in too.

[@DXCommanderHQ]

Indeed!

[@sparky71a]

Hi Call, like you used to work the CBs back in the 80s,i went through to early 90s. Had lots of kit,some i kept. Wind the clock forward to lock down.Kept kit as i moved around the country over the years. Then i found your videos,got kit out,messed around in receive, antenna building,got a scanner,then got a Yaesu 450D. Now keep passing foundation mocks on Radio tutor,need to bite the bullet in the next couple of weeks and take it. Just had some kevlar line from you,built a much better EFHW with 80m coil,just last night. 40m band very busy. At 52 years young,married with grown up daughter,we are now empty nesters. I have ADHD.Radio as it turns out is still my saviour😂 Thanks Cal,this is all your fault,and im very gratefull ❤👍

[@DXCommanderHQ]

All my fault! Excellent! And welcome back!!

[@nb6175]

Great stuff, Callum. I love these overview videos that give the bare bones of a topic. So much of learning is simply being told about a direction you can look in. Almost like polarizing our mental antennas? lol.

[@paulsengupta971]

"a direction you can look in" - through polarised sunglasses?

[@paul-olof]

TY TY TY I'm so glad I watched this. I've just begun pre-study of my HAM license and am bouncing around to better understands the 'why's' of it all and your videos are great

[@DXCommanderHQ]

Excellent!

[@gregedwards9901]

Thank you Callum. I really appreciate these nuggets of knowledge.

[@DXCommanderHQ]

My pleasure!

[@Blutnase]

I am unable to reply to your reply to me, so I'm posting anew with something more than "Something nice" to say I really appreciate the hard work you do, and I very much appreciate all the fascinating information I've learned since I found you. All the best.

[@DXCommanderHQ]

Yes comments to comments are buried. I appreciate your attention. Thank you.

[@ScatManAust]

Arrrrh Lightbulb moment. Fading and polarization differences. Thanks cal.

[@DXCommanderHQ]

Boom!

[@thomasperina2990]

Hello Lord Callum: Thank you for this video sir 🙏. I really needed this refresher. I haven't gone horizontal since the 70's & early 80's with my quad beam. I truly didn't remember anything about circular polarization . Well I learned something new from the master. Thank you again sir , God Bless, & my best to Wendy and both dogs. TMP, Unit 22 from N.J.

[@DXCommanderHQ]

Awe.. You are always so kind with your comments, thank you!

[@DukeDave1]

Thank you Callum great Chat I like the discussion about polarization. Interesting the helical pattern typically used for satellite comms on UHF. I believe. Let me know if I'm in error. Thanks. Dave. 73.

[@DXCommanderHQ]

I think you might be right!

[@wildweasel6898]

Thanks buddy I got my license watching your videos along with HRCC and a few other lads. Your doing a great job brother.

[@DXCommanderHQ]

That's awesome - good work!

[@N8XMD]

Thank you Callum! The dual VFO with each hooked up to either a horizontal or vertical antenna makes so much sense in regards to "fading" signals. Brilliant and salient!!

[@MvM-nv9hk]

this type of info is just what the hobby makes interesting Callum👌

[@David-km8in]

Hi Cal, I always recommend your channel to my amateur friends. Especially those who are taking the foundation course. All the best David M0DUU

[@DXCommanderHQ]

Thanks David!

[@mattmiegel]

I find your channel very informative And fun too watch, keep it up mate. And I'm looking forward to talking to you on the air.

[@DXCommanderHQ]

Can't wait!

[@JeffSkymaster]

Always good stuff and i love your Ballon visuals for antenna Radiation, Brilliant!

[@nigelpugh7191]

Hi Callum, another great video brilliant keep it up 👍 73 from 🏴󠁧󠁢󠁷󠁬󠁳󠁿GW0TPF

[@DXCommanderHQ]

Awe.. Thanks old friend!

[@trevorbond1325]

Another great video Callum. Thanks for doing it. VA3TBI Ontario 🇨🇦

[@DXCommanderHQ]

My pleasure!

[@matthewsadler1542]

Thank you sir Callum, just starting in the hobby have today taken a couple of mock foundation tests and crushed them. Shall book up the real test at the end of the month 73

[@NickFrom1228]

Good discussion. I've been working to understand polarization and this helps clarify this concept quite well. Thanks!

[@DXCommanderHQ]

Great to hear!

[@deankq4adj125]

Well done, very interesting and educational. Keep them coming!

[@law7564]

Thanks, Cal, for the excellent video. Studying for my extra, has been very helpful in understanding some of that.

[@DXCommanderHQ]

Very welcome!

[@richardtwyning]

Interesting as always, plus the added feature of a happy flying saucer picture 😁 Keep up the good work Cal. 73s M7GTX 👍

[@DXCommanderHQ]

Glad you liked it!

[@mascote10d]

A subject that many forget, both in 11 Mts and old school radio amateurs. CR7BKW

[@chrisb012]

Always love these videos, they’ve been great for me to revise the ‘basics’ before taking my intermediate exam. Came in handy, as there were a couple of questions based on polarisation. Cheers for your help! De 2E0IXV

[@DXCommanderHQ]

Great to hear!

[@lyriconii]

Always a pleasure. Clear information. Always entertaining !

[@DXCommanderHQ]

I appreciate that

[@AubsUK]

Short or long videos, who cares, as long as you get your point across. Thanks Colin :)

[@DXCommanderHQ]

Aubs! Hello mate.

[@j.p.thearmoredchef]

Thank you Callum. I send a lot of your videos to friends because frankly you are much better at explaining these concepts than I am!

[@DXCommanderHQ]

Awesome, thank you!

[@robertmeyer4744]

that was really good. some satellites use circular polarization because it is spinning. that why some satellite antenna's have a spiral in front of the dish. once RF bounces it can easy change polarization . can be salt water or ionosphere .long DX is multi hop. bounce off the sea water . salt water is a great reflector. love listen to live stream with stereo head phones. best way to hear the 2 VFO's. 73's

[@DXCommanderHQ]

Ah! You do too? Yes headphones is good fun with 2 VFOs

[@robertmeyer4744]

@@DXCommanderHQ I only have a 1 VFO radio ,so I listen to your live stream for that effect .

[@BrandonLeeBrown]

For DX it is true that the polarization doesn't matter, unless you can switch polarizations, to see which is strongest that day, but most manmade and atmospheric interference is vertical. This may aid reception with a horizontal antenna, by reducing noise. Powerline (mains) radiate mainly vertically, as do electrical storms. On the lower part of HF, such as 40 meters, 80 meters and 160 meters, the ground (earth) can act as a reflector, but in the high bands, 20 meters, 15 meters and 10 meters, the ground (earth) can cause a great deal of loss. Horizontal antennas generally suffer from ground loss more than vertical antennas, at the same heights. The general rule to reduce ground loss with vertical antennas is to have the bottom of the antenna at least one antenna length above the ground. For horizontal antennas, for a similar reduction in ground loss, often two antenna lengths (widths) above the ground is required.

[@watrocket]

Very interesting . I never really thought much about what the causes of "fade" are. I will be trying out listening to both horizontal and vertical through my 2- VFO's. I appreciate the explanation and illustrations! Thanks, look forward to meeting you on the bands again in the future. Mark de KK4HUK

[@DXCommanderHQ]

2 x VFOs? A must.

[@paulsengupta971]

@@DXCommanderHQ I only have a single VFO but I have two radios and I keep meaning to set up dual antennas and then feed the audio from each radio into one ear of a headset. I think I'll need some sort of isolation transformer or two.

[@tamstutz921]

Thank you for this! Very interesting and informative.

[@DXCommanderHQ]

My pleasure!

[@pn4694]

As always, a real pleasure: information and humour - very nice mix. Gotta love it! CU on the band, 73

[@DXCommanderHQ]

Thank you!!!

[@mel904]

Always very informative. I enjoy them all.

[@DXCommanderHQ]

Awesome, thank you!

[@sveinfarstad3897]

That was allot of bananas, Callum 🤘

[@DXCommanderHQ]

HAHA Yes!

[@paulwynneroberts1731]

Thanks Callum. I find these videos very interesting. thank you 2W0IEP 73

[@DXCommanderHQ]

Glad you like them!

[@MIKROWAVE1]

Great Stuff Cal! The old standard for VHF AM was Horizontal (TV was as well) and the challenge for mobile was how to get Omnidirectional Horizontal on the car? The answer was the Halo or The Turnstile and lately the terminated Double or Quad helix. All of these can give you omni horizontal polarization. ER I mean Polarisation...

[@DXCommanderHQ]

I recall the Halo, yes..

[@vicmiller7191]

Good explaination, thanks Callum. 73 and take care.

[@DXCommanderHQ]

Thanks, you too!

[@aandpman]

Thanks Cal, I love watching. Even as an Extra class, I learn a lot, and keep my knoledge reviewed. Keep ep the good work!

[@DXCommanderHQ]

Awesome, thank you!

[@jacko101]

Nice one Cal, never understood circular polarisation, but now I do! Cheers mate.

[@elodiemirza]

Another great educational video Callum :)

[@DXCommanderHQ]

Thank you!

[@Professzore]

Something nice. Already subscribed. 🙂All the best Cal!

[@DXCommanderHQ]

Awesome! Thank you!

[@Professzore]

@@DXCommanderHQ Cal, if I have a good topic (technically some "why should or should not" questions) about antennas, where can I verbosely describe it for you?

[@rowdyron4111]

Fascinating presentation. Thank you.

[@DXCommanderHQ]

Thank you too!

[@jshrader13]

I've wondered about this for a long time actually and could never find a satisfactorily simple explanation. But now you've actually piqued my interest and I think I'm going to try a little experiment. I've always just used verticals, or a vertical J pole for 2m, but now I'm curious to see the effect of a horizontal 2m wire dipole! I'm sure it'll be worse reception and transmission, but for sake of education and experimentation, I'm definitely going to try it!

[@DXCommanderHQ]

Yes do it.. But ideally find someone with a small Yagi and your signal will explode! LOL

[@2013Davey]

Great foundation information and very well presented.... and you were right about the drawing of the car. 73 from MM7FGU

[@DXCommanderHQ]

HAHA Yes!!

[@m7trsradio]

Great video Callum. Not thought about the signal bouncing around to change from H to V. That explains there people sound like aliens, so my XYL would say. Great job my Elma. 73

[@djernairchecks]

I work as a broadcast engineer and circular is how we do it for FM broadcast, stacked circularly polarized antennas either half or full wave spaced, (sometimes different spacing) allows for incredibly high ERP in both planes, in the case of one my stations 40kw transmitter power out into 6 bay circular polarized antenna nets 100kw ERP with the antennas 320m above ground - 73 KY4SZ

[@DXCommanderHQ]

Wow.. That's amazing!

[@tonysquibb]

This video is very helpful as are all your videos. Thank you

[@DXCommanderHQ]

You're very welcome!

[@Ibsonlovesyou]

Still loving it Cal 👍

[@jamesemery1]

good info and easily understood that is a credit too you.

[@dallasthomas6519]

Thanks Cal, maybe a bit specialized but you make it easy to understand. Maybe you should publish your book of drawings with the simple and fun ways you put it.

[@DXCommanderHQ]

It's in the plan!

[@REKlaus]

Thank you for the time you share with us by doing your videos. Always good info and some fun. Off the topic of this video, have you ever thought or actually done a real life comparison between the DXCommander and a 41 foot vertical with a 9:1 transformer. The 41 foot verticals where quite popular for a time here in the states. I was considered as a "Flag pole" antenna so somewhat stealthy. Have a great week 73 K1AUS.

[@DXCommanderHQ]

I have that in the plan this summer.. But a biggger experiment with a 49:1, no radials, some radial, ground mounted.. etc.. etc.. I have a line-of-sight target (my house) and we'll do this on 10m band to discount "ground wave" (eg 40m would give us that).

[@va2boy]

Good explanation Sir Callum

[@DXCommanderHQ]

Thanks!

[@user-yh7mv7jd1l]

I’ve noticed that where it matters a lot is on satellites, for on the same channel (frequency) you have two independent signals coming out. I remember I used to tune my satellite receiver with those massive antennas that were very hard to set up because you had to rotate the antenna to catch all the geostationary satellites in the precise right spot. 20 years ago the frequencies were around 3 or 5 GHz, if I remember well. Polarization in those very high frequencies was extremely critical, for as I said, in the same frequency you had two transponders, a vertical and a horizontally polarized one. The antenna was changed from one phase to another phase by means of using and actuator (a servo engine) which would move the tiny antenna 90 or as many degrees as you wished in order to tune the reception of either the horizontal or the other 90 degree signal from the transponder. Yes, on the same frequency you had two different emissions, or satellite Tv channels. Polarization is very critical at those higher frequencies. KO6DEV. 73

[@DXCommanderHQ]

Amazing.. Thanks!

[@paulsengupta971]

Those big dishes were C band. These days TV broadcasts are mostly 10-12GHz (Ku band), so even higher. The LNBs for these have two antennas, one horizontal, one vertical and you switch between them by supplying different voltages to the LNB. It used to be that the channels were frequency spaced and polarisation spaced, i.e. the first channel was V, the next frequency up was H, then the next one V, etc. But as you say, these days with digital broadcasts, there are sometimes a H and V transponder on the same frequency, as a bit of interference doesn't matter with a digital signal.

[@MikeJones-xf2qh]

As always, great content. More theory the better imo.

[@DXCommanderHQ]

Lovely!

[@ILoveMyBikes]

Things I find interesting about circular polarisation is for multi path rejection and that antenna orientation is not critical.

[@m0ngo]

Two people hold a skipping rope. One person holds the rope still, the other shakes the skipping rope left and right: the rope propagates a horizontal wave. Next, while the rope is still held at one end, the other end is swung up and down, then the rope propagates a vertical wave.

[@joecarty8579]

You can actually take the polarisation a step further, we ran a pirate system over 30 years back using polarisation modulation, (switching between left and right circular) and it’s was pretty much undetectable as it just appeared as a blank carrier.

[@MidlifeRenaissanceMan]

One evening, after dark, I was chatting on SSB and AM on 40M with a mate who is a few suburbs away. 15 minute drive. We were getting noticeable phasing even though it was a local signal. Most pronounced on 40m. 80m was solid as was 20m. But 40m had this phasey, notch’s my sweep going on. Figured it must have been the NVIS competing with the ground wave and that delay notching / comb filtering from the NVIS

[@DXCommanderHQ]

Yes.. Speed of light.. It's a bugger!

[@dannyjardine8828]

Thanks Callum!

[@srinivasnyayapathi9083]

Great video

[@DXCommanderHQ]

Thanks!

[@billzebub2000]

Very informative and entertaining. 👍🏻

[@DXCommanderHQ]

Thanks! 👍

[@9165RADIOS]

Thanks Callum - Yes, I DID stay awake, all the way to the end!

[@DXCommanderHQ]

Woo-Hoo!

[@paulsengupta971]

Oh, was I supposed....oh, um....

[@donausmus4281]

I always learn something here. Thanks! K1DLA

[@DXCommanderHQ]

Glad to hear it!

[@bradabrown]

Love the instruction!

[@ryank5tar]

A polarizing subject indeed.

[@DXCommanderHQ]

HAHA!!

[@kapplerphoto]

Thanks for explaining why QSB occurs

[@DXCommanderHQ]

Well.. It's ONE of the reasons ..

[@paulsengupta971]

@@DXCommanderHQ I give your example of signals going from one ear to the other as proof that QSB is often due to polarisation changes through the ionosphere when I'm explaining all this to someone. No one talks to me at parties any more! (Who am I kidding, no one invites me to parties!)

[@maartenc6099]

One things where circulair polarisation is very usefull is working satelite. These "birds" are thumbeling around the earth and polarisation can shift, so being curculaire is and advantage.

[@DXCommanderHQ]

Yes, I meant to mention that!

[@threadripper979]

Good info, as always.

[@turbochardged]

love the explanation!

[@DXCommanderHQ]

Thank you for the nice comment!

[@halcollins4293]

Years ago the local 2m repeater antenna failed and they switched to a horizontal antenna that wasn’t being used. I was in the edge and ended up buying a mag mount squalo to be able to talk to my Mom who was a ham.

[@SentinelOneLove]

Informative video

[@Thinks-First]

I was told that my satellite TV dish would lose signal during rain storms not so much due to degradation of the signal through the increased moisture but rather due to polarization change through the moisture.

[@DXCommanderHQ]

Fascinating.. May be right actually..

[@maartenc6099]

No it is signal degradation. The satelite is above the rainclouds and can not get through. On the shf band you can work dx with rainclouds scatter, so use the rainclouds to reflect your signal.

[@Thinks-First]

@@maartenc6099 The man who told me this, Dick K2RIW (SK) was an (ARRL award winning) lifetime professional radio engineer and assured me that signal degradation through clouds (moisture) is NOT correct. It's polarization shifting that causes the degradation.

[@Thinks-First]

@@DXCommanderHQ It is. Dick K2RIW (SK) was a professional radio engineer and we had many discussions on our "tech net" local repeater about this phenomenon.

[@willdive6770]

Hi. Heard you mention refraction in your video. In the mock exam qustions there is one particular question that is very misleading when it gives the answer of radio waves being "reflected" by the ionosphere. As i'm sure you are aware, reflection and refraction are NOT the same thing so why have the RSGB got it in there? Keep up the good work, really enjoy the videos.

[@2013Davey]

Yes you are correct... but at foundation level I feel that the (over) simplification is forgivable as there is an element of reflection, lol

[@DXCommanderHQ]

Yeah.. Watch my previous video. I very clearly indicate the difference. The FOUNDATION book does also use other various words to describe the phemomena.. "bounce" and "reflect" etc.

[@willdive6770]

@@2013Davey The difference could affect the outcome between a pass and a fail for borderline students. Where the book states that refraction takes place the answer to the test question is given as reflection, this could, potentially, divert the student to an alternative answer.

[@CanispaterChristmas]

BRILLIANT!!!@! 👍📡💥

[@TheKomunyaka]

My ham license exam is coming soon, so, please, go on, Callum!

[@DXCommanderHQ]

Will do!

[@JoshColletta]

I forget which company it was, but if you look up some of Bob Heil's talks to ham clubs (there are a BUNCH of them here on KZbin), he describes and shows pictures of an antenna that he called a "spiral array," which was essentially a Yagi in which the elements were twisted progressively along the boom from front to back. The idea was to reduce fading by catching signals as they turned outside the horizontal plane, and he claimed that it worked quite well. It seems that it wasn't quite the commercial success that the manufacturer had hoped, because it's rare enough that he found it necessary to show and explain it to every club he spoke to, but I for one am curious what kind of measurable improvement it eked out.

[@DXCommanderHQ]

Interesting!

[@paulsengupta971]

@@DXCommanderHQ There's an experiment to try...

[@davem0udb]

Good stuff Cal

[@DXCommanderHQ]

Much appreciated

[@Lonewadi6242]

Thank you, sir!

[@DXCommanderHQ]

Very welcome!

[@migsvensurfing6310]

I am very polarized so I got it.

[@johnmiller4750]

Interesting thanks love it when people add the out takes to. Any ideas about dielectric transmissions ??? Tesla used this atmospheric charged boundaries

[@DXCommanderHQ]

No, I'm sorry - that's new for me..

[@daveengstrom9250]

I like that circular polarization stuff (reminds me of a string of doughnuts).

[@bassangler73]

I want 10 of your vapes!!! You see purple trees, that must be good stuff!!! 😂😂😂😂😂

[@DXCommanderHQ]

The purple trees are wonderful!

[@piquat1]

Something to ponder. You know those weird little computer generated antennas they're designing now? If you don't know what I'm talking about, google it. Wonder what polarization they are? They're all odd little shapes, mostly really high frequency.

[@DXCommanderHQ]

Multiple polarisations.. Like an inverted L.. Has both components.

[@piquat1]

@@DXCommanderHQ Interesting, thanks.

[@HAMFunko4pdi]

I have a question Calumm I work Satelittes and I just erected a Yaesu 5500 rotor with two Yagis for UHF and VHF. I made the horizontal for working the sats. Now except for the ISS most sats are tumbling. I always thought polarisation didn't matter am I wrong?

[@DXCommanderHQ]

If it's tumbling, it won't matter. Correct.

[@paulsengupta971]

If they are spinning, they'll be RHCP (more than likely RH). If you have a yagi, it won't matter, but better still would be a cross yagi set up for RHCP. Or a helical.

[@FromthehamshackwithNJ4Z]

Great Stuff!!!

[@DXCommanderHQ]

Thanks!

[@timdbl7804]

A further thought which might help folk enhance their understanding: "Circular polarisation" seems to be one of the several confusing miss-nomae from the RF professionals! It seems to be an oxymoron. I think it should be called "Rotating polarisation" 😀

[@texasfrontiersman8245]

Is this why cubicle quads perform so well

[@DXCommanderHQ]

Quads perform well because it's a directional antenna - only the PDL2 was switchable in polarisation. I think!

[@stirlingpark6145]

It may have been asked; why is ssb (VHF/UHF) normally horizontallly polorarised? for 7m down to say 40m I can understand that it is easier (space wise) to use horizontal , but for shorter wavelenthgths? Does it have anything to do with the effect that a vertical mast might have?

[@DXCommanderHQ]

It's a convention - probably because mechanically (and RF-wise) it's better to mount a yagi horizontally due to potential interference on a steel mast if mounted vertically. SSB, being a "longer" distance mode therefore became horizontal.

[@psycardis]

So, hypothetically, all these new cars that have slanted antennas are trading fuel efficiency for radio signal? Meaning if you were to connect a vertical antenna, you might gain a few dB?

[@DXCommanderHQ]

Depends on what you are trying to receive.. Of course, broadcast is circular so no need to worry :)

[@jmollo55]

You had a post recently with a hydraulic pump up mast ... do you by chance have a make/model ??? i know you said something about it being from a fire department ... please and thank you ... i have little to no yard/garden to mount antenna .. if i could find two of them i could put at each end of driveway to run a wire between them .. thanx

[@DXCommanderHQ]

It's a Clark Mast.

[@johnmiller4750]

Can you make an all polarisation differentiator that automatically locks to the polarisation of received signals??? And a way of communicating what polarisation a signal is being received on with respect to its transmission angle I wonder for auto phase adjustment

[@DXCommanderHQ]

Well, I suppose you could.. Interesting possibilities!

[@Apollo.308]

I’m watching just about all your videos at this point. I never assume to know it all and I’m far from it. Cheers!

[@DXCommanderHQ]

Me too! :)

[@timdbl7804]

Hi Callum, from where do you get the 20 dB loss figure in the case of crossed polarisation?

[@DXCommanderHQ]

Cross polarisation or different polarisation? I have seen many demos.. But remember, as soon as you vary the difference, that 20dB quickly becomes 15, 10 etc.

[@timdbl7804]

@@DXCommanderHQ Hi Callum, thanks for your reply; sorry for the ambiguity in my question. I mean different polarisations..... My understanding is that, in free space, there is nill coupling of, for example, a horizontally-polarised wave to a vertically-polarised antenna. (Back on earth, there might be some coupling owing to reflections from objects, effects of the ionosphere etc., but the value of this is very variable)