nRF51822 rf layout

Question

Hi, 
 I am new to microwave board design, so I'd like a little advice please. I have attached photos of the 2.4ghz section of my board and would like to know if the component layout is okay. The circuit should be identical (with reference to DC resistance) to the reference design, but I just need to know if it's okay to rearrange the component locations/orientations as I've done.

I noticed in the reference design there are not ground planes near the RF section. I presume that's to reduce the stray capacitance and thereby keeping the impedance more constant. 
 Should I add keepout zones?

Thanks in advance!

Martin Sivertsen · Accepted Answer

Hi Brian, 
 Brian said: 1. Does the distance from the ground plane to the antenna look correct? 
 The distance to ground on the top layer looks good, the distance to ground on the bottom layer is a little bit tight. It looks like you're using this antenna, and the distance to ground should be 0.46 mm. 
 
 Brian said: 2. Did I connect the antenna ground correctly by bringing the ground plane right up to the pad on both top/bottom layer? 
 Yes, we have seen good performance connecting it like that. 
 I'd also recommend adding a shunt component (usually a 1.0 pF capacitor) right up to the antenna feed point to be able to fine tune the antenna, we usually get good results by just adjusting the length of the antenna and the value of the capacitor: 
 
 Best regards, 
 Martin S.

nRF51822 rf layout

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