[time-nuts] Difference in GPS antennas

Magnus Danielson magnus at rubidium.dyndns.org
Sat Aug 15 14:58:33 UTC 2009


Bruce Griffiths wrote:
> Hal Murray wrote:
>>> My Panasonic VIC100 antenna had a few screws to hold the bottom to the
>>> plastic cone top.  The bottom had an o-ring seal that stuck a little
>>> but was still pretty easy to slide the bottom from the top half.
>>> Inside was a patch antenna on top of a pcb. 
>>>     
>> Thanks.  I tried again and it came apart easily.  There is an O-ring but no 
>> glue.  (I wonder why I didn't get it the first try.)
>>
>> The antenna isn't a patch.  (Or I don't recognize it as such.)
>>
>> It's a cylinder, 2 inches tall, 3/4 inch in dia, sticking up over a 2 inch 
>> square PCB that's screwed into an aluminum base place.
>>
>> It's made of flexible PCB material wrapped around to make a cylinder.  The 
>> outside bottom 3/4 inch is a plane.  There is an obvious solder joint line 
>> closing the plane.  The inside top has 4 fingers spiraling around at 45 
>> degrees.  The lower inside part (opposite the plane) has some wiggles in some 
>> traces, but I haven't figured out the equivalent circuit.
>>
>>
>>   
> Thats a quadrifilar helix antenna.

A quite traditional antenna form.

Not sure I have one of those around here.

Cheers,
Magnus




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