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ChristiaanJ
3rd Feb 2008, 20:01
Question from an ancient.....

Remember the long HF wire aerials from just behind the cockpit to the fin?
Like DC-4 or Connie?

Those had to go at some point....
On Concorde they were replaced by two deep "saw-cut" slot aerials in the fin (visible on old photos of Concorde 002, painted over ever since).
Not overly efficient, RF-wise.... the HF currents set up in the surrounding structure were enough to wag the tail via the rate gyros installed in that area.... until we put in some more filters.

Since my long-ago Concorde days I've totally lost contact with present-day HF aeronautical radio systems, but I'm still curious.
Anybody here willing to, very briefly, explain what the HF aerials on, say, an A320 or a B777 are like?

Fargoo
3rd Feb 2008, 20:28
They still use slot antennas in the fin with HF couplers either in the fin or in the cabin above the rear galley.

ChristiaanJ
3rd Feb 2008, 20:37
Thanks Fargoo!
Any pictures where one could distinguish them?

Radar Love
5th Feb 2008, 05:42
Hi Christiaan,

On the 737NG the HF aerials are hidden away inside the leading edge of the fin, the tech site has a nice schematic of where most of the aerials are located..

Communications (http://www.b737.org.uk/communications.htm) and just scroll to the bottom of the page.

As you can see on this pic from airliners.net the HF set up isn't visible...

Photos: Boeing 737-86N Aircraft Pictures | Airliners.net (http://www.airliners.net/photo/XL-Airways/Boeing-737-86N/1303511/M/)

I'd be quite interested if anyone has a diagram (with accompanying pilot-friendly description!) of how the HF system is set up inside :8

Hope that helps!