Re: [SI-LIST] : RF Design Question

Adrian Shiner (adrian.shiner@virgin.net)
Sat, 10 Jul 1999 21:37:29 +0100

A thorough study of high frequency antenna types will assist you in understanding.

When you are playing with circuits having nano to pico second rise times then PCB track size, shape and spacing affect the circuit performance both as intended and as a "transmitter".

The days of the PCB layout just being a matter of squeezing all the bits into the available space have long gone. If you are designing products intended for use in the European Union, then I suggest you have a good look at the EU
EMC Directive and the associated generic harmonized standards for emission and immunity.

If you want to discuss this further, I am happy to assist.

Best wishes

Adrian

Dave Hoover wrote:

> Hello,
> I'm fairly new to this group and really enjoy
> absorbing as much as I can from here. Being as
> I'm from the PCB fab side, I'm always tantalized
> (YANKED) into the electrical properties side
> of circuits/PCBs. Now I have a question.
> I have a customer (phone card manufacturer) who
> indicates that teardropping trace to pad junctions
> increases the the capacitance enough to completely
> change his EMC characteristics of the trace.
> Can this be so? (Sanity Check time)
> Next, there was ground pours around pads that had
> an octagon shape. We contourized the clearance which
> made it circular. Can this do the same EMC impact?
> In an industry where I've always been told that for
> reliability reasons we should always do the above
> mentioned for DFM. Now......in an RF environment the
> same reliability things change the designed in
> characteristics? I'm lost..........
> Any and all responses will be greatly appreciated.
>
> David Hoover
> Field Application Engineer
>
> McCurdy Circuits
> (714) 974-0401 ext 34
> (714) 974-3596 fax
> dhoover@McCurdy.com
> http://www.mccurdy.com
>
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