Installation Manual

3
transmission line ensures good impedance control and can be implemented in an outer PCB layer as
needed in this case. A SMA female connector has been used to feed the line.
The interface board is realized on a FR4, 4-layers PCB. Substrate material is characterized by relative
permittivity εr = 4.6 ± 0.4 @ 1 GHz, TanD= 0.019 ÷ 0.026 @ 1 GHz.
A characteristic impedance of nearly 50 Ω is achieved using trace width = 1.1 mm, clearance from
coplanar ground plane = 0.3 mm each side. The line uses reference ground plane on layer 3, while
copper is removed from layer 2 underneath the line. Height of trace above ground plane is 1.335 mm.
Calculated characteristic impedance is 51.6 Ω, estimated line loss is less than 0.1 dB. The line
geometry is shown below:
Transmission Line Measurements
An HP8753E VNA (Full-2-port calibration) has been used in this measurement session.
A calibrated coaxial cable has been soldered at the pad corresponding to RF output; a SMA connector
has been soldered to the board in order to characterize the losses of the transmission line including
the connector itself. During Return Loss / impedance measurements, the transmission line has been
terminated to 50 Ω load.
Return Loss plot of line under test is shown below: