I'm using this chip antenna with a 868MHz radio (RFM12B): http://www.johansontechnology.com/datasheets/antennas/0868AT43A0020.pdf
According to the datasheet's mounting considerations there's a trace that's supposed to go out from the antenna. What is the reason for this? Due to tight space i'd have to drop this with a via to the bottom of the board and do this there, is this ok? I guess the via will have quite a big impact on the RF signals. If not, can i do something "similar" with a same length but slightly different shape? Or is it better to leave it out entirely? Are there other ways of doing this to achieve a "decent compromise"?
Related to this the feed line should have 50 ohm impedance. According to this: http://www.eeweb.com/toolbox/microstrip-impedance I've calculated the trace width to be about 115 mil. This seems very big.. I'm using a regular 1.6 mm FR4 board with 1 oz copper. Am I missing something?
Also I'm assuming this should definitely not have sharp corners so the trace is rounded
(cannot be perfectly straight as in the datasheet), right?