Contactless electromagnetic measuring system using conventional calibration algorithms to determine scattering parameters

Abstract

Abstract. In this paper, a contactless measuring system for the determination of the S-parameters of planar circuits is presented. With a contactless measuring system it is possible to characterise a device-under-test (DUT) embedded in a planar circuit environment without cutting the planar transmission lines connecting the DUT. The technique utilizes four identical capacitive probes in conjunction with a vector network analyser (VNA). For the usage of electromagnetic probes compared to other coupling techniques like the electro-optic probing, there is no need for expensive and complex equipment in addition to the typical equipment of a common microwave laboratory. The S-parameters are determined accurately using conventional calibration methods. A simple analytical model for the representation of the basic characteristics is developed. Furthermore, the influences on the S-parameters as a result of a variation in the coupling are presented. With the knowledge of the system characteristics, an accurate contactless measurement system is set up. The comparison between conventional and contactless measurements in a frequency range of 1-20 GHz shows a very good agreement with a phase error smaller than 1 • .

Contactless vector network analysis using diversity calibration with capacitive and inductive coupled probes

“…3. System dynamics against the frequency for a probe distance of l=100 mm; DUT: 50 load -Data from Zelder and Eul (2006).…”

“…A similar analytical calculation can be done using two identical capacitive probes (CC) Zelder and Eul (2006). The dynamics for a contactless measurement system with two capacitive probes results in:…”

“…De Groote et al (2006) and Yhland and Stenarson (2006) applied electromagnetic loops as contactless coupling structures. In contrast to this approach, by Zelder et al (2007) and Stenarson et al (2001), pure inductive or capacitive probes are used. A principle setup of a contactless vector network analyzer system using two probes is shown in Fig.…”

“…Short-Open-Load-Thru (SOLT) Schiek (1999) or selfcalibration methods like Thru-Reflect-Line (TRL) Engen and Hoer (1979). One disadvantage of this system is, that for certain probe distances a calibration is not possible which is shown by Zelder et al (2007). This limits the measurement bandwidth.…”

“…This limits the measurement bandwidth. For the measurement system with two capacitive probes the critical distances have been calculated by Zelder and Eul (2006).…”