A Compact High-sensitivity Tangential E-Probe With Resonator and Coupled
Balun
Shang Zhang1,2, Zhenguo Liu1, 2, 3,
Zhipeng Chen1, 2, Mengzi Li1, 2,
Weibing Lu1, 2, 3
1 State Key Laboratory of Millimeter Waves,
Southeast University, Nanjing China.
2 School of Information Science and Engineering,
Southeast University, Nanjing, China.
3 Purple Mountain Lab., Nanjing, China.
Email: liuzhenguo@seu.edu.cn
A
compact high-sensitivity probe for sensing up tangential E-field is
proposed and measured in this paper. The probe is consisted of an
electric dipole with patches used to induce the tangential E-field, a
resonator made up of open circuit stubs (capacitor) and short circuit
stubs (inductor), for achieving a specific resonance, and a compact
coupled balun for transforming the differential- mode voltage into the
single output voltage and impedance matching. The probe is fabricated on
five-layer dielectric lamina. Compared with the referenced broadband
probe, the measured \({|S}_{12}|\) of the probe is enhanced by 18.81 dB.
The proposed probe in this paper is validated with simulation and
measurement.
Introduction: With the increase of operating frequency modern
radio frequency (RF) integrated circuits have become more and more
miniaturized, which results printed circuit board (PCB) has become more
dense. Thus, unexpected electromagnetic radiation coupling between some
sensitive components will affect the normal operation of RF integrated
circuits, resulting in very serious electromagnetic compatibility (EMC)
issues [1]. To improve the performance of RF integrated circuits, a
proper electromagnetic analysis model is needed to determine the
location of interference source in the RF integrated circuits, which is
the key to solve EMC issues.
In recent year, the near-field scanning technology for detection
location of interference sources has been developed rapidly [2-3],
which play significant role in EMC problems. The probe used to sample
E-field component is the key part of the near-field scanning
measurements. Much effort has been devoted to studying the normal
E-field probe [4-6], such as how to design the miniaturized probe
and improve the working frequency band of probe for wideband
measurements, but less attention has been paid to the probe detected the
tangential component of E-field. Yan proposed a broadband tangential
E-probe loaded with electric dipole and integrated balun for the
near-field measurement covering the GPS band [7]. However, for
integrated circuits working in narrowband, the high-sensitivity probe
detected tangential E-field can convey more power to the instruments,
therefore, a weaker electric field can be detected. A resonant
tangential E-probe [10] has high sensitivity for sensing up the weak
electric field, compared with it, the structure of the resonator in the
probe proposed in this work is simpler and the coupled balun without via
fence has more concise structure. Moreover, the performance of this
probe is better.
In this paper, a compact high-sensitivity probe for capturing tangential
E-field with resonator and coupled balun is suitable for locating the
noisy sources or the electromagnetic interference sources of circuits
working in narrow band. The proposed probe has been fabricated and
measured.
Probe
structure: Fig. 1 shows the overall structure of the probe with
resonator and coupled balun based on 4-layer PCB. Fig. 2(a) exhibits the
layout of the probe with physical dimensions. The structure from top to
bottom is the top layer, the middle layer 1, the middle layer 2 and the
bottom layer. Both the top and bottom layers are copper planes, which
can provide the currents return paths and shield the external field. The
middle 1 layer is the metal grounding plane of coplanar waveguide. In
the middle 2 layer, the folded electric dipole and the resonator
composed of open- and short-circuit stubs as well as the coupled balun
are cascaded in turn. Fig. 2(b) shows the stack-up of the resonator
probe, which is made up of three layers of 0.254-mm thick Rogers4350B
and two layers of 0.2 mm thick Rogers4450F.