[time-nuts] Clarification of purpose of trace in PCB board

David Forbes dforbes at dakotacom.net
Thu Aug 3 21:56:34 UTC 2006


xaos wrote:

> Hello everyone,
> 
> In my daily eBay search for (gps*, distrib*)
> 
> I found item: 330012701666
> http://cgi.ebay.com/Distribution-Amplifier-6-Way-Output-MWT-Powered-Divider_W0QQitemZ330012701666QQihZ014QQcategoryZ25392QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
> 
> which is an 806-849 MHz Distribution amplifier.
> 
> When I looked at the JPEG:
> 
> http://www.ridgeequipment.com/images/6-way-amp-0213.jpg
> 
> I was a bit confused as the the purpose of the
> large circular trace which held a "snake" like
> trace within it.
> 
> At first glance, it seemed that the circular trace was connected
> at both ands to the "snake" trace but there is a resistor
> there.
> 
> So it seems that the "snake" like trace should be the
> same length of the semi-circle to match the phase.
> 
> My question is: why would there be a resistor there?
> 
> Why have the two semi-circular ends connected in such a way?
> 
> Regards,
> 
> George Hrysanthopoulos, N2FGX

George,

See this page for a description of why that resistor is needed in a 
Wilkinson power divider (which is what you're looking at).

http://www.microwaves101.com/encyclopedia/Wilkinson_splitters.cfm







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