oceanic: Surcouf-Vertical Loop

ID: 194760
This article refers to the model: Surcouf avec cadre (Océanic, ITT Océanic; Paris)

? oceanic: Surcouf-Vertical Loop 
16.Jul.09 01:23

Joe Sousa (USA)
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Joe Sousa

Radio enthusiasts, how does the vertical loop antenna drum work in the Oceanic Surcouf?

Every AM loop antenna I have ever seen always had a horizontally oriented axis.

The reason for this is that AM transmitters generally transmit with a vertical mast, which polarizes the magnetic field into horizontal magnetic field line circles.

I can't help but wonder if French transmitters used a different polarization, perhaps with some other benefit that I am not aware of, like lower noise, better imunity from fading, or rejection of stations with a conventional polarization.

What bands is the drum for?



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? Its a simple Frame 
16.Jul.09 09:42

Hans M. Knoll (D)
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Hans M. Knoll

Hello Joe.


Inside of the Box two Frames ar mounted. 1 for LW and 90° shiftet 1 for MW.

Around  the Box an single Wire are woundet,   to prevent Static Antenna Efffect (shielding)

Here one  Sample without screen.




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Clever Loops 
16.Jul.09 18:45

Joe Sousa (USA)
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Joe Sousa

Hello Hans,

So these loops were simpler than they seemed. I have seen E-field shields before and they are very effective against a lot of man-made interference, which tends to be electric field disturbance. The loose spiral is a single ended grounded wire.

The crossed loops make very efficient use of space. The stray coupling that is eliminated with the 90o mount helps keep the Q of each loop the highest it can be. This is most useful at the high end of the PO band, where Q is hardest to get.

Another thought comes back from an earlier discussion about shorting inductor turns: When the tuning capacitor is moved from the GO to the PO, the self resonance of the disconnectd GO loop is likely to fall within the PO band at an unpredictable frequency. This would greatly disturb the operation of the PO loop.




p.s.: Wave names in French, English and German

GO=Grandes Ondes   LW=Long Waves=Langwelle

PO=Petites Ondes   MW=Medium Waves=Mittelwelle AM=Amplitude Modulation BC=BroadCast

OC=Ondes Courtes   SW=Short Wave  KW=Kurzwelle

Note the different wave size appreciation in French vs English or German.

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