Three questions about RF design

[KP]

I have doubts about some RF question.(see attachment) if you find it interested would you answer my 3 questions?
q1: What's the purpose to put so many vias on beside along the track?
q2: Why the bottom side (see picture) pour a wide copper plane and exposed to air (no solder mask)?
q3: By maintain 16mil track line to achieve 50 Ohm impedance , what do we need to know?
Hopefully someone can help me.
Yours sincere aid is my great pleasure and honor.

 

[khouly]

Hittete Rf board

A1) these vias are to make the island beside the track are connected very well to the ground , so this transmission line is very good coplaner one , with very good stable Z0

A2) there is no need to but a solder mask , coz it is ground , and this should be connected to the heat sink or so

A3) u need to know the er of the board , its thickness , the copper thickness

khouly