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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3 comments:

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...

HI BRAD --
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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