Dae-Chan Kim

Characterization Method of Electric Field Probe by Using Transfer Standard in GTEM Cell

In this paper, we introduce a simple and wideband characterization method for electric field probes using a transfer standard. As a transfer standard, a thin disk-type reference probe that can operate from 50 to 1000 MHz is used and calibrated using a micro transverse electromagnetic (mu-TEM) cell. A gigahertz transverse electromagnetic (GTEM) cell is used to generate a reference electric field. It has been shown that the uncertainty of the proposed method can be increased due to the imperfection of the field condition in the cell. According to the measurement result, the proposed characterization method for the electric probes agrees within 6.3%, compared with the method that uses the TEM cell and standard antennas in a fully anechoic chamber.

Determining Noise Temperature of a Noise Source Using Calibrated Noise Sources and an RF Attenuator

A system to measure the noise temperature (NT) of noise sources is implemented in the frequency range of 18-26.5 GHz for the case where noise sources commercially available have only one nominal NT, e.g., 9500 K being equivalent to 15-dB excess noise ratio. For the Y-factor method, two noise sources, i.e., a noise source and another with a radio-frequency attenuator, serve as the standard noise sources. The noise power output of the noise sources are measured using a commercial noise figure measurement instrument. Measurement results are presented, and its uncertainty has been evaluated to be 0.23-0.25 dB (k = 2) .

Uncertainty Analysis in EVM Measurement Using a Monte Carlo Simulation

This paper proposes an error vector magnitude (EVM) measurement method for a wideband code-division multiple-access source using a real-time oscilloscope. The EVM values are extracted from the measured waveform using a signal processing that finds the appropriate carrier phase and symbol timing. Measurement uncertainty is also evaluated based on a Monte Carlo simulation, where the errors from the real-time oscilloscope and the signal processing are taken into account. The measured EVM of a source at 900 MHz is (0.2586 ± 0.0040)%, (0.2617 ± 0.0060)%, and (0.2543 ± 0.0078)% at 95% confidence level when the real-time oscilloscope has a bandwidth of 2, 4, and 20 GHz, respectively.

Fabrication of Small Reference Probe and Its Application

This paper presents a disk-type small reference probe operating up to 1 GHz as an electric field transfer sensor. The probe is calibrated using a mu-TEM cell and demonstrates a wide useable electric field strength range. Design and calibration methods are presented. The probe is suitable for testing and comparing the performances of reference field generation systems, both TEM cells and antennas. As an application, a technique for measuring the antenna gain is proposed and applied to open-ended waveguide antennas

Uncertainty analysis in EVM measurement using a Monte-Carlo simulation

An error vector magnitude (EVM) measurement method for W-CDMA source is proposed using a real time oscilloscope with traceability to SI unit. Also measurement uncertainty is evaluated based on a Monte-Carlo simulation, which takes into account the errors from the oscilloscope and signal processing. The measured EVM of a source at 900 MHz is 0.2535% ± 0.0057% at 95% confidence level.

W-Band Permittivity Measurements Using a Free-Space Material Measurement Technique

In this paper, a free-space material measurement technique is discussed in W-band(75~110 GHz). For the accurate measurement of S-parameters of an MUT(Material Under Test) in free space, a W-band quasi-optical free-space material measurement system, less affected by the measurement environments, is discussed, and GRL(Gated Reflect Line) method for calibrating the measurement system is described. Proposed technique is verified for `Air` and measurement results for arystal plates of thickness 1.1 mm, 2 mm, 2.75 mm and 5 mm are also shown.

A method for estimating the complex residual errors of a VNA in one-port measurements

This paper presents a method using multiple air lines for estimating the complex residual errors of a VNA (Vector Network Analyzer) being calibrated by an ‘OSL’ (Open-Short-Load) technique, which is widely used for one-port measurements. It uses a simple circle fit algorithm, together with some techniques to be used for improving the accuracy in finding the center and radius of a circle in the complex (reflection coefficient) plane from measured calibration data.

Characterization method of electric field strength sensor by using transfer standard in GTEM cell

In the present study, we introduce a wideband calibration method of electric field strength sensors by using a gigahertz transverse electromagnetic (GTEM) cell and a reference electric field sensor. A preliminary comparison shows good agreement between the proposed method and other ones. Another measurement result will be presented at the conference.

Phase analysis of coaxial short and open circuits

Phase characteristics of coaxial short and open circuits used to calibrate reflectometers are analyzed by using the lossy transmission line theory and mode-matching method based on the cosine/sine-Fourier transforms. Calculated phases of short and open circuits with Type-N, 7 mm and 3.5 mm connectors are compared with ones predicted from the calibration kit parameters provided by the manufacturer.

Precise Measurements of Waveguide Scattering Parameters in G-Band

This paper discusses difficulties in precise measurements of the scattering parameters in (sub-)millimeter-wave range and tips for more accurate measurements, and provides measurement examples in the G-band(140~220 GHz). First, one investigates the differences in operating principles of scattering parameters measurement systems used in microwave and (sub-)millimeter-wave ranges and describes tips for better operation of the (sub-)millimeter-wave scattering parameters measurement system. In addition, one describes tips for better transmission properties and connection repeatability of waveguides and a precise measurement method for devices with small reflection coefficients.