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Antennas are strange things!

I can understand how antennas are fickle, I have a j-pole mounted in my attic. I just had a new shingled roof installed (old roof removed), and now, for some reason my reception has improved!

I don't know why, but I noticed the difference right away. Does not make sense to me, but I'll go with it. YD
 
under an electron microscope, antenna material is made up of tiny mirrors....everytime the wire is bent, the mirrors angles are changed:drool::scratch2:
 
Mortsnets said:
You are right it seems totally random. My best reception is with the T on it's side ( |--- ).
Click to expand...

I believe the theory is that vertical is the preferred position with FM radio now being vertically polarized and all.

Best,
Tyler
 
Interesting thread... Most FMs (in the US anyway) are circular, and a few are still horizontal. The funny thing about polarization, is that it doesn't matter that much after the signal encounters a few reflective surfaces. You may receive a horizontally-polarized reflection of a vertically polarized station, or vice versa. Furthermore, if you get your antenna perfect today, someone might park their car in a different spot down the street and you'll need to start over again from scratch. There are no guarantees with VHF!

I also saw tropospheric ducting mentioned... That is interesting stuff! Earlier this summer I was driving through a remote mountainous stretch of Oregon, where I can ordinarily barely pull in one fuzzy FM country station for about a 40 mile stretch. Just for fun, I tried my FM tuner and... Wow! There was a station on every frequency, loud and clear! These signals were coming mostly from Arizona, New Mexico, and Texas. I spent most of my 100 mile drive listening to a station from Texas in crystal clear FM stereo! It may never happen that same way again.
 
G'day all, interesting on the polarisation aspects. I know that here in Austalia in the 1990's 'mixed polarisation' was the official requirement as I did volunteer work with a Community FM station and I actually saw the strange looking transmit circularly polarised antennas we used on transmit, however since then I suspect the standards may have changed, as one commercial rock FM I know of uses exclusively vertical polarisation on their transmitter antenna stack.

Yes it is true the polarisation becomes scattered especially on the lower HF frequencies, but strangely enough on the VHF FM frequencies the polarisation can remained quite 'defined' for an extended distance.

An example, on a particular FM station with vertical transmitter polarisation (the one I previously mentioned), I used a horizontally polarised small yagi to receive it, and the signal was reasonable, but not strong.

I changed the yagi to vertical polarisation and the signal went to full scale in full stereo! That station is about 100 miles away. With antennas and radio generally, strange things happen. :yes: Regards, Felix (vk4fuq) aka catman.
 
catman said:
With antennas and radio generally, strange things happen. :yes: Regards, Felix (vk4fuq) aka catman.
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The other day on 11 meters (AM), I was talking on my vert omni to a guy in Texas (I'm in AZ) who was running a flat side beam. He had me on the backside as well. When he pointed it at me, I lost him. It was really strange.
 
It's called backscatter. I have worked all over South America on 10 Meters with the beam pointed straight north and if you turned the beam toward South America you would lose the signal.
 
ZeroJunk said:
It's called backscatter. I have worked all over South America on 10 Meters with the beam pointed straight north and if you turned the beam toward South America you would lose the signal.
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Cool, I've never seen that before. It was weird watching the signal (on both ends) click down like that as the rotor turned toward me.
 
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G'day all, one of the strangest things I've ever experienced was on 20 m one afternoon back in the mid 1980's.

A station I was talking to became rather 'distorted' sounding, like a 'Dalek'. I was told I sounded the same.

Everybody else on the band at the time also sounded similiar. Some strange kind of ionospheric disturbance was the cause, apparently! Regards, Felix (vk4fuq) aka catman.
 
G'day mate, yes it probably was Auroral Flutter, but it was rare to experience it at these latitudes. :scratch2: Regards, Felix (vk4fuq) aka catman.
 
Yankee Dog said:
I can understand how antennas are fickle, I have a j-pole mounted in my attic. I just had a new shingled roof installed (old roof removed), and now, for some reason my reception has improved!

I don't know why, but I noticed the difference right away. Does not make sense to me, but I'll go with it. YD
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New shingles don't have nickel in them anymore like years ago so this could be the reason you are getting better reception now.
 
Aha! That could explain it. The only thing I could come up with (not knowing the info you just provided) was old shingle ashphalt, new is fiberglass? But your explanation makes more sense. YD
 
CaspianSutekhDalek1.jpg



Po-La-Rize! PO-LA-rize! Ahhhh!


cats-vs-daleks
 
catman said:
A station I was talking to became rather 'distorted' sounding, like a 'Dalek'. I was told I sounded the same. ...
Click to expand...

Reference is the Doctor Who TV show. :alien:

Daleks are humorless, obstreperous cyborgs who frequently blurt out "Ex-TER-MIN-ate!" in a fuzz-pedal voice before firing beam weapons from their extensions.

The irony here is the dangerous Daleks, who several times nearly exterminated planet earth, are thwarted by cute whiskered fuzzy meddlers.
 
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