Crossed loop DF systems

[Anonymous]

Several quite modern yachts and a few FVs here in Fiumicino have crossed loop DFs on their masts. Why would anyone bother these days, or am I missing something?

 

[William_H]

I have no idea why they would have LF/MF loop for D/F.

However I wonder if it might not be some kind of D/F for VHF ie for finding EPIRB beacon 121.5mhz or finding a VHF com.

These are more often in the form of 4 VHF 1/4 wave whips set at 1/4 wave spacing on a flat surface. So no, no idea olewill

 

[rogerthebodger]

Can you post a picture

 

[Anonymous]

[ QUOTE ]
Can you post a picture

[/ QUOTE ]It's not very convenient to do that right now but this webpage has a photo, see fig. 7

http://www.astrosol.ch/thisandthat/5379039a840e79e07/index.html

There are two loops of about 30cm diameter at 90 degrees to each other, presumably connected to a goniometer or some kind of ADF system. We used to have one in the 1970s and 80s pre-GPS (we skipped Decca). Within the limitations of MF RDF it is a very good system but why would anyone want one today? Particularly a yacht? I keep an ancient SeaFix? handheld in a locker as an insurance policy against the world's GPS going down or being made selectively unavailable to me /forums/images/graemlins/wink.gif but I wouldn't want crossed loops on my mast.

 

[rogerthebodger]

I just wondered if it might be a weather satellite receiving antenna but they tend to be helical about that size other than that don't know