Based on the Product Specification v1.0, the antenna load impedance should be 15Ω+j88Ω.
I checked the antenna impedance based on Figure 32.
The simulation result is
For the differential impedance Zd, I used the following equation
The simulated result is about 21Ω+j43Ω, far from 15Ω+j88Ω.
Anyone can help to check this problem.
I want to fine tune the external circuit based on the S11 of my own PCB antenna.
thanks in advance.
-Tony