Spectracom WWVB Antenna
More for the fun of it than anything else (and to test the data capture software I was writing for my HP 3585B spectrum analyzer), here are a couple of pictures of the WWVB signal received using the Spectracom model 8206 amplified antenna.
The antenna is mounted about 1.5M above ground, oriented so that its long side faces roughly east/west. The antenna has a preamplifier and needs DC power to work; to meet this requirement, I had it hooked to the Spectracom 8164 WWVB receiver and tapped the signal off with a "tee" connector (using a DC block to protect the analyzer).
The first image is a single sweep, though a very slow one given the narrow resolution of the analyzer filter. WWVB sends a timecode by dipping the carrier power by 10dB once per second. The very narrow dips in the signal near the peak are remnants of this modulation.
This image captures multiple sweeps, using a "max hold" feature to show the highest level at any given point:
