Fig. 2 (b) Stack-up of the probe
as the induced end in the front of the probe, mainly to increase the
contact area with the tangential electric field to enhance the
sensitivity of this probe. The end of the resonator is connected with
the dipole and the other end is connected to the coupled balun which
converts the differential mode voltage into the common mode voltage. The
other end of the coupled balun is connected with the strip line which is
connected to conductor-backed coplanar waveguide CB-CPW through a signal
via. The current generated at the probe tip through the electromagnetic
field to be measured, and then flows to the SMA connector through the
resonator, the coupled balun, the signal via and the CB-CPW.
A. Resonator: Compared with the broadband probe, the electric
field probe with resonator has higher sensitivity working at narrow-band
frequency [8]. The capacitor and inductor are the parts of the
resonator, open-circuited and short-circuited transmission line can be
used for the resonator which has a high quality factor. The resonator
shown in Fig. 3 is loaded into the probe designed in the paper, the
function of open-circuited stub is equivalent to capacitor, and the
function of short-circuited stub is equivalent to inductor. The length
of open-circuited stub and short-circuited stub can be used to tune the
resonant frequency. Fig. 3 shows the specific dimensions of
open-circuited stub and short-circuited stub when the probe works at
1.320 GHz resonant frequency. The initial value is set to be less than\(\lambda/8\) and the specific values can be obtained by sweeping
parameters to achieve specific resonance in HFSS.