1. What will be the negative effects?
2. Doesn't the antenna mount act like a shield?
3. How large a hole is required?
BTW, I am a novice at RF.
George
On Sat, 2006-06-03 at 01:14 +0200, Hans Nieuwenhuis wrote:
On Fri, 2 Jun 2006 09:02:55 -0500 "James Cotton" <[EMAIL PROTECTED]> wrote: > > A few things about shielding. I'd suggest you put a ground plane over the entire board to shield the msp430 of unwanted radiation coming from either your transmitter or some external source. Don' t shield the antenna though :-). > > Yea, I can do that - Initially I was worried about having to route too > much on the bottom layer but it ended up being only a few traces My strategy usually is to route all of the traces until you get this "Ping! routing complete!" message and then I throw in the ground planes. Because I routed all of the ground connections too I am sure they don't end up on some unconnected ground plane island (The DRC does not check on this so beware!). Use the 'j' key to clear up all the traces that got swallowed up by the ground plane. > > > You already shielded the radio part but it is better to also put another groundplane on the solder layer and drill lots of vias between (i.e. on a 0.1 inch grid) the component and solder layer. This will help avoid unwanted oscillations on your radio board. > > Is there an easy way to do this aside from the tedium of manually > placing many holes? Not that I know of, but maybe someone more experienced with PCB can give more info. As a minimum I would suggest to put at least one via as close to every ground connection in your schematic, preferably two (just in case one via ends up broken). Be sure to disable the "Enable enforce DRC clearance" inside the settings menu and place thermals over each via. An automatic via grid option would be very handy for this purpose, but I haven't even seen that option in 4-digit maintenance/yr. PCB software (*cough* Mentor *cough*). > > > I am not sure what you want to do with you antenna. Do you want to choose between external or internal antenna? On you schematics you connected them in series as on the board it looks like you can switch between them. > > Yeah, in the schematic I had to connect the F-monopole to ground on > both sides to stop it from throwing DRC errors all the time since it > is a single piece of metal. They are both connected to ground on one > end and depending which cap you populate selects the antenna. > > > Did you use gsch2pcb to produce the board from the schematics? > > Yeah, I had to delete the m4 directory though. I have been using John > Luciani's footprints and a few I hand made. > To respond to John Luciani's post, I think he mentioned this application note: http://www.chipcon.com/files/AN_040_Folded_Dipole_Antenna_for_CC24XX_1_0.pdf
