X and O and why Alaska starts with "alas"

[KL7AJ]

Well, emails have been streaming in about my December QST article on X and O mode propagation, and I haven't even seen my article in print yet. I just got my NOVEMBER issue. Well, this is the price you pay for being at the end of the earth.

Anyway...several very astute readers asked if you could reduce selective fading by using circular polarization. This is an EXCELLENT question, and I don't have a complete answer....I need more people to experiment with this and see.

If X and O waves interfere with each other you would certainly have some wave cancellation. However, as I mentioned the X and O waves diverge in AZIMUTH as well, so it's proably not too likely that you would have both waves landing in the same location, EXCEPT in NVIS situations. But there hasn't been enough actual field experimentation to conclusively determine this. This would be a GREAT experiment a lot of hams could do very easily.

I can't say how gratifying it is to have people ask this sort of question....it means they're really paying attention! I think we may have a major contribution to some practical radio methods in the making here.

Eric

[KL7AJ]

I might also add that the time of flight between the X and the O waves is sufficiently different that you would not likely get phase cancellation, even under NVIS conditions (which is why these two signals are so easy to discriminate in the first place). The time scale difference between the X and the O waves is on the order of milliseconds, or hundreds of microseconds. (You can sometimes HEAR the difference in the time-of flight of the X and O signals by listening to WWV..sometimes you'll hear a double click on the ticks)

But again, this is wide open for experimentation

Eric

[K8ERV]

Alaska should start with ALY. But you know that.

TOM K8ERV Montrose Colo

[KL7AJ]

Alaska should start with ALY. But you know that.

TOM K8ERV Montrose Colo

We changed the name when we kicked the Russians out.

[AC0FP]

Your not alone in Kansas, no December QST delivered either. This is what happens when you live in "fly over country".

fp

[KA5S]

Well, emails have been streaming in about my December QST article on X and O mode propagation, and I haven't even seen my article in print yet. I just got my NOVEMBER issue. Well, this is the price you pay for being at the end of the earth.

Anyway...several very astute readers asked if you could reduce selective fading by using circular polarization. This is an EXCELLENT question, and I don't have a complete answer....I need more people to experiment with this and see....

I have a couple of Werlatone 6-120 Mhz quadrature hybrids and might try it. Not set up to reverse phasing between TX and RX though I do have a transfer relay. And my yard is not big enough now.

Hah!

Cortland
KA5S

[KL7AJ]

I have a couple of Werlatone 6-120 Mhz quadrature hybrids now.

Hah!

Cortland
KA5S

Mercy, those must be some expensive little puppies! The Anzac 2-8 MHz hybrids we had all over Hipas were about $180 a pop!

Eric

[KA5S]

Mercy, those must be some expensive little puppies! The Anzac 2-8 MHz hybrids we had all over Hipas were about $180 a pop!

Eric

Ebay and still expensive but If igured worth it. As I mentioned some time ago here I have a couple of Anzac 2-32 MHz hybrids. THOSE were abouy $40 weach, a really good deal. Never did put up two loops though. The Werlatones look like they were used to run a pair of ampifiers at 90 degees with a 10 watt unit on the inputs and the higher power (IIRC 250 watts) on the outputs. Not quite low frq enough for my MARS nets locally.

Matching to untuned dipoles could be interesting; I could use a pair of LDG's remote and hope they were about the same phase shift, not much hope they would be, though. Maybe for receving a 6 dB attenuator at each antenna would be good enough.

X and O...Iceland Spar anyone?


Cortland
KA5S

[KL7AJ]

Ebay and still expensive but If igured worth it. As I mentioned some time ago here I have a couple of Anzac 2-32 MHz hybrids. THOSE were abouy $40 weach, a really good deal. Never did put up two loops though. The Werlatones look like they were used to run a pair of ampifiers at 90 degees with a 10 watt unit on the inputs and the higher power (IIRC 250 watts) on the outputs. Not quite low frq enough for my MARS nets locally.

Matching to untuned dipoles could be interesting; I could use a pair of LDG's remote and hope they were about the same phase shift, not much hope they would be, though. Maybe for receving a 6 dB attenuator at each antenna would be good enough.

X and O...Iceland Spar anyone?


Cortland
KA5S

You have to be careful about tuning the dipoles to resonance, because any reactance will create additional phase shift. In fact, you can actually USE reactive antennas to create the 90 degree shift you need, but you have to be intentional about it. One thing you can't do is ignore it!

eric

[KD5PME]

Just got Dec QST today and went straightaway to your article. Very good indeed. I now have another project on my list