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Archive for January 2nd, 2010

WWVB Groundwave Signal Is Vertically Polarized

I suppose this shouldn’t be surprising, but the nature of groundwave propagation pretty much requires vertical polarization: the E-field is perpendicular to the ground.

Perforce, that means the H-field is parallel to the ground, which means that ferrite bar antennas must be horizontal in order to work properly.

A simple experiment with the Alpha-Geek Clock conclusively demonstrates this. Turning it vertically is just as bad as aiming a bar end directly at Colorado: the signal drops right into the noise.

Horizontal and broadside to Colorado, it’s fine.

Alas, I’d been hoping to tuck the bar antenna inside the Totally Featureless Clock I’ve been building. The ideal location, mounted vertically behind the right-hand digit at the end of the circuit board, as far from the Arduino Pro as possible, just isn’t going to work. Good location, wrong orientation!

I want to avoid an external antenna or a tall case. Drat!

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