I am controlling for the impedance of the antenna connection exiting my cellular modem using a coplanar waveguide with ground plane, but I am not sure how to calculate the non-grounded portion of the microstrip as it exits the ground plane and enters the antenna (pin 3). I am afraid that if I do not specify the correct antenna track width at that location, there will be an impedance discontinuity at that un-grounded portion (at both pin 3 and pin 4 ground return). The impedance calculators I'm using always assume a ground plane and they do not provide an impedance calculation without the ground plane where it enters the antenna itself. Alternately, I may need to measure (as best I can) the antenna eval board track width, but it would have been best if that information was documented in the data sheet. Can you let me know what that track width should be to optimize the antenna performance?