Topband: Polarization on 160m

[Yuri Blanarovich]

 Speaking of "two ears"
Going back to using two Drake R4B receivers, two antennas, one on each 
ear, there would be times when "two ears" heard the signal, while 
switching to each other there would be nil. I think that was some DSP 
going on in the head.
BTW Drake R4B is still one of the best receivers for weak signals 
reception, no crystal filters in the path to fuzzy the signals. LC in IF 
chain. DSRs are now very close.

Yuri, K3BU 
 
 On Wed, Nov 28, 2018 at 12:04 PM, Tree wrote:
 
 > WIll add my two cents to this discussion.
>
> One thing I have experience with is diversity reception both on 160 
> and 80
> meters.  Often - I would be using my TX antenna in one ear and a 
> beverage
> in another.  On 80 meters, the TX antenna was a 4 square.  On 160, 
> either a
> vertical or two element phased array.
>
> I found on 80 meters - when running JAs in a contest - if I only used 
> one
> antenna - I would almost always miss one letter of the JA's callsign 
> and
> have to ask for a repeat...  but with diversity - the signal would 
> float
> around in my head and I could almost always get the whole call the 
> first
> time.
>
> I can hear this effect on 160 as well as signals float around.  I 
> can't
> prove this is just polarization - as it could be different angles of 
> signal
> arrival - but it sure re-enforces the point that having different 
> kinds of
> RX antennas for different situations is never a bad thing.
>
> I have experienced some sunrise openings where a low dipole has worked
> well.  There are times when my directive receive antennas seem to be 
> broken
> - which is another indication of high angles.
>
> Tree N6TR
>
> On Wed, Nov 28, 2018 at 8:51 AM Yuri Blanarovich  wrote:
>
>> Not knowing about "gyros", but when operating and having vertical and
>> horizontal antennas available, I remember times when QSB was 
>> happening
>> on one antenna, switching to the "other" polarization antenna would
>> bring the signals up.
>> My conclusion was that at the times the signal's polarization was
>> rolling around, especially when far DX.
>>
>> Yuri, K3BU, VE3BMV, VE1BY
>>
>>
>>  On Wed, Nov 28, 2018 at 09:22 AM, Robert Parkes via Topband wrote:
>>
>>>
>>> Polarization on 160m
>>>
>>> Interesting discussion and one I suspect we wish could fully
>>> comprehend !
>>>
>>> When the wave front meets the ionosphere and the wave splits the
>>> critical frequency is different for the two waves, commonly known as
>>> foc and fxc.
>>> This difference (from memory) is half the gyrofrequency and can 
>>> often
>>> be seen on Ionosonde plots with two sets of reflections. The gyro
>>> frequency depends on the strength of the magnetic field at that 
>>> point
>>> of the ionosphere so can vary from 700kHz to 1.4MHz where the 
>>> radiated
>>> wave interacts with the Ionosphere Layer be it, E layer or F layer.
>>>
>>> Being radio amateurs and pushing the envelope we are trying to make
>>> that illusive QSO so we need to excite a propagation path which is
>>> normally at the limit in order to chase the DX.
>>> Assuming conditions are favourable, and if the angle of arrival and
>>> critical frequency is such that it favours both wave fronts then for 
>>> a
>>> single and multi-hop transmission both the O-wave and the X-wave 
>>> will
>>> be propagated.
>>>
>>> The higher frequency of the two wave fronts, the X-wave may 
>>> propagate
>>> which could result in a QSO whilst those around us may not have 
>>> quite
>>> the same favourable conditions and only the O-wave is propagated  on 
>>> a
>>> differeing path while the X-Wavecould fall by the wayside and not be
>>> propagated.
>>> One result of all this variability could result in what has been
>>> called spotlight or torchlight propagation.  I recall Eric K3NA 
>>> giving
>>> a talk along these lines when referring to 3B7C 160m operations and
>>> how that spotlight moved across North America during the course of 
>>> his
>>> opening to the US.
>>> There is a possibility that Circular Polarisation would assist
>>> with both the O and X wave modes of propagation and it could be 
>>> argued
>>> that a "compromise" Inv-L antenna provides this with its Vertical 
>>> and
>>> Horizontal elements making up the antenna and resulting mixed
>>> polarisation.After all a number of amateurs have had good success 
>>> with
>>> an Inv-L.
>>>
>>> 73sBob ParkesG3REP(ex - S21YP, 4S7RPG, A45XF, VS5RP, P29PR)
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