AVR-Chat

Eric Engler wrote:
> --- In AVR-Chat@yahoogroups.com, Russell Shaw <rjshaw@...> wrote:
>> Richard Cooke wrote:
>>> We need some help with a small hand held RF remote controller project.
>>> We're willing to pay for the help.  Basically we need some help with
>>> the matching circuit from the nRF905 to a small helical antenna.
>  
>> At high freqs (2.4GHz etc), RF matching circuits are only reliably done
>> using simulations that include the pcb taking into account the physical
>> dimensions of the tracks and component footprints. 
> 
> That's a very true statement. It's almost impossible to match a 2.4
> Ghz antenna to a circuit board unless you have a lot of UHF/Microwave
> experience. Making it work on the bench is one thing, but making it
> work well for a mass production board is a lot more difficult. I'd
> definitely recommend that you pay an RF engineer to help you.

IME (i'm an RF designer), critical layout problems begin kind of around
100-200MHz. Even at 50MHz you have to know what you're doing, but at 500MHz,
even if you know everything about what's happening, you still need the
numerical analysis of a CAD program to include the distributed pcb layout
effects. As long as the soldered-on components and pcb have consistant
characteristics, mass production is no problem. Changing brands of
components between runs can be a problem.