An Enhanced-Sensitivity Tangential Electric Field Probe With Tunable Resonant Frequency

Abstract

A novel enhanced-sensitivity tangential <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</i> -field probe with tunable resonant frequency is proposed in this paper. This <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</i> -field probe consists of a front-end electric dipole induction part, tunable coupling resonators, a balun transmission section, and a coplanar waveguide transmission part. By introducing an improved electric dipole-induced element and resonant transmission, the detection sensitivity of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</i> -field probe can be significantly improved. Varactor diodes are loaded into the coupling resonators to achieve an adjustable resonant center frequency, thereby minimizing the contradiction between the high sensitivity and test bandwidth of the resonant <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</i> -field probe. A prototype of this tunable resonant frequency probe was fabricated and measured. When the reverse bias voltage applied to the varactors was tuned from 0 V to 20 V, the probe could obtain enhanced-sensitivity tangential <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</i> -field detection within the frequency band of 1.61-2.30 GHz. Moreover, this probe was also adopted to measure the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</i> -field components in some areas of the microstrip line and antenna based on FR4. This probe can improve detection efficiency and reduce test costs on the premise of enhanced sensitivity detection. It has broad application prospects for near-field measurement in the future.