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CC2500 Dipole Antenna Trace Width

Apollyon
Prodigy 15 points
Other Parts Discussed in Thread: CC2500

I will be using PCB with thickness of 60.2 mils (Er = 4.2 ± 0.3) and 1.4 mils (1 oz) copper on top. These parameters gives trace width of 113.5 mils (~ 2.88 mm) and in the reference design it is 0.6 mm.

Question-1: So will there be any changes in the Reference Design provided in CC2500 Dipole Antenna Design Note (DN004) or should i just increase the antenna trace width to 2.88 mm from 0.6 mm (If so, then will H3 remain the same)? 



Question-2: For 10th Harmonic, distance between via's:  lvia = c / fres * (Er)^1/2 = 5.97 mm (according to AN068, Page-4). But looking at the distance between the via's in the reference design this calculation don't make sense :(. 


 
Looking at the above picture the distance between the vias looks more like ~ 3 mm.

Question-3: I'm confused with the connections in Socket_2. Why pin_18 is not grounded and why Output to L1 is given from two pins (7 and 9)



  • 0
    TI__Genius 12545 points

    Have you checked this app note?? (http://www.ti.com/lit/an/swra236a/swra236a.pdf)

     The 10th harmonic distance was given as a upper limit for the distance between consecutive vias. In general it is preferred to have as many vias, especially close and around the RF path. Reducing the radiations of harmonics and providing a solid contact between ground planes.

    Pin 18 was probably used as a control line on the board, which was later removed. That explains why it is not grounded as the others.

    The two supply pins are added as a case of redundancy