November 15, 2009

antennas at Bolinas

click photo for full-size image
photo by Donald Kinney

I showed another slightly different version of this scene yesterday, but I like this better.

These antennas are Coast Guard property, but for years the ship-to-shore station KPH blasted out shipping traffic lists and weather reports to ships all over the Pacific Ocean.   Oh, you know, stuff like -- "Ahoy there, Pacific Pineapple -- swing by United Fruit and pick up another load"

click photo for full-size image
photo by Donald Kinney

This is a very huge and expensive Yagi antenna, which they can rotate for directionality.   It can pick up very weak signals from very far away because it has a high Gain factor.   Antennas must conform to a precise fraction of the length of the radio wave -- they're tuned to whatever frequency they're designed to receive or broadcast.

click photo for full-size image
photo by Donald Kinney

Quite the spider-web of cables and wires.   Do you see the four deer in the foreground?

These antennas are located out near the bird observatory, a few miles north of Bolinas on the Mesa.

click photo for full-size image
photo by Donald Kinney

Kind of an interesting design, I think.   Art and science mingle...

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Brad said...

Interesting antennas, Don. That 2nd one is not only a Yagi, but a Log Periodic Array. Covers the whole HF band continuously, rather than just being tuned to a handful of narrow bands.

There are two of those behind Stanford University, in the open space hiking area called the Dish; named for the huge (150 feet in diameter) radio telescope dish antenna you see from 280. Pretty big when your underneath it - it sits on a giant turntable for rotation.

If you're ever down the Peninsula, let me know and I'll take you there...

Love the next day's photo of the birds!

AphotoAday said...

Thanks for the information on the Log Periodic Array... I've gotta go look that one up -- in a book no less... I have that AARL Antenna Handbook that has been taking up space for the past ten or twelve years...

Broadband -- that makes sense... And I'm guessing that's a Coast Guard thing -- I forgot to get a good look at the sign...

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