Re: gEDA-user: PCB antenna - short circuit

[Dave N6NZ <n6nz@xxxxxxxx>]

John Griessen wrote:
>> Tamas Szabo wrote:
>   Since all part of the antenna
>>> lines consist of pads, it seems to be a short circuit between the 
>>> terminals 
> 
> Another thing to explore is about how in PCB pads
> aren't handled just the
> same DRC-wise as lines and no lines are
> allowed in a footprint (as of now).
> 
> What if you use two pad numbers, put a bunch of lines-that-become-pads
> in your footprint, and let one pad number touch the other?
> 
> Does PCB allow that?  Is that what you already did?
> 
> John
> 
> Here's two more work-arounds:
> 
> 1.   Let the symbol be two pins, but same number.  Then everything else will be OK,
> you just won't have a footprint the will check for installed backwards -- who cares?

Well, presumably the antenna driver is two different pins from a amp 
that drives the two sides of the transmission line.  So it will still 
appear to DRC as two nets being shorted.

> 
> 2.   Don't use a symbol or footprint at all, just an area of layout saved and importable
> where you like, and noted on schematics as a layout area by comments.  I like this way.
> Your printed wiring antenna IS a layout zone.

Or....

1. On the schematic, don't use a symbol, just connect driver pin 1 and 
driver pin 2 with a short on the schematic.  You can draw the "short" on 
the schematic in an artistic fashion to look like an antenna.

2. In PCB, you will have to pull in the antenna footprint manually.  Or 
I suppose you could have an unconnected symbol on the schematic have the 
antenna as a footprint so that the netlister will include the symbol. 
Or maybe even have an antenna symbol, and let it connect it's two pins 
with a 'net' attribute that ties the two pins together.  Actually... 
that last idea is probably best, but you'll have to test it... it's been 
a while since I tried a snakey trick like that.

3. In PCB, connect the driver pins to the antenna footprint normally. 
The antenna footprint should have the same pin number on both ends.  It 
will look like a short. DRC expects a short.  Everybody is now happy.

-dave



> 
> John
> 



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