Coaxial Line to Microstrip transition
Transition refers to interconnection between two planar transmission lines. In order to have low reflection and low insertion loss, it should have perfect matching of impedance and E-M fields. It should have continuous transmission lines for effective coupling. Bandwidth of operation is very important and depends on modes supported in the transmission lines used for transition.
Coaxial Line to Microstrip transition is used most popularly in PCB where microstrip circuit is fed using 50 Ohm coaxial line. The most common configurations used are edge mounting and vertical mounting type as shown in the figure 1 and figure 2 respectively. In the edge mounting type transition, coaxial line is connected to microstrip line at the edge of the PCB.
In the vertical mounting type of transition, center conductor of coaxial line passes through the PCB. It intersects the microstrip line orthogonally as shown.