Michael Gadringer | Graz University of Technology (original) (raw)

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Papers by Michael Gadringer

IEEE Transactions on Instrumentation and Measurement, 2022

2021 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting (APS/URSI), Dec 4, 2021

This paper presents a miniaturized HF/UHF dual-band antenna fed by a dual-interface RFID chip. Th... more This paper presents a miniaturized HF/UHF dual-band antenna fed by a dual-interface RFID chip. The main goal of the antenna design is to achieve a compact, cost-effective, multi-purpose, and high performance RFID transponder. The proposed antenna utilizes the HF coil as a ground for a meandered monopole antenna operating at UHF band. An inductive network is adopted to achieve a conjugate matching between the antenna and the UHF chip interface. Measurements of a transponder prototype show a power sensitivity of −16.5 dBm, which corresponds to a realized antenna gain of approximately −1 dBi at 860 MHz.

2021 29th Telecommunications Forum (TELFOR), Nov 23, 2021

This paper presents an asymmetric single-stage Doherty power amplifier (DPA) in MMIC form using O... more This paper presents an asymmetric single-stage Doherty power amplifier (DPA) in MMIC form using OMMIC GaN transistors operating at 25 GHz. The DPA implements a dynamic input power division technique in contrast with the more conventional fixed input power division. The technique mentioned above splits the input power by sending most of the power to the main PA when the peak PA is not conducting. Therefore, the power sent to the peak PA gradually increases after it reaches a certain input power level and starts conducting. This behavior is achieved by taking advantage of the non-linear behavior that characterizes the gate capacitance of a transistor in class C operation. As a result, the input impedance of the peak PA will be matched appropriately for saturation. However, it will show a higher real-valued impedance at power levels below back-off (BO) operation. This will have a substantial positive impact on the PAE and small-signal gain degradation at BO that would occur if fixed input power division was to be used. The DPA reaches a maximum output power of 33.8 dBm at a PAE of 28% and efficiency of 22% for 7.6dB OBO, keeping a level of PAE over 16% over the 7.6dB to maximum output power range.

Elektrotechnik Und Informationstechnik, Jun 27, 2018

This paper presents a delay line element with meandered slots being part of a substrate integrate... more This paper presents a delay line element with meandered slots being part of a substrate integrated waveguide (SIW) structure and its numerical analysis. The proposed delay line element is designed by using a coplanar waveguide (CPW) configuration due its low dispersion compared to other transition configurations. The proposed delay line element is designed on a substrate of Rogers RO4360 with a thickness of 1.524 mm. Its numerical characterization is conducted in terms of return loss, insertion loss and group delay time. By numerical analysis and synthesis, the optimum delay line element can be designed and the desired characteristics can be achieved for operation in the frequency range of 1.4-2.8 GHz with a return loss up to 40 dB at a frequency around 1.75 GHz. Additionally, an almost flat insertion loss with values around 0.5 dB and a likewise nearly constant time delay around 1 ns is achieved over the desired frequency band.

The interface between a probe station and an active or passive component on a printed circuit boa... more The interface between a probe station and an active or passive component on a printed circuit board is of great importance for RF systems operating in the mm-wave frequency range. The landing pads provide the transition between a coplanar measurement device and a microstrip interface. This paper addresses the design issues of such landing pads focusing on finding the optimal design enabling multiline deembedding with a measurement error better than 0.1dB.

arXiv (Cornell University), Feb 27, 2023

arXiv (Cornell University), Sep 19, 2022

2021 18th European Radar Conference (EuRAD), Apr 5, 2022

Automotive radar sensors are key elements for Advanced Driver Assistance Systems and autonomous d... more Automotive radar sensors are key elements for Advanced Driver Assistance Systems and autonomous driving. To test the behaviour of these systems in complex and potentially dangerous traffic scenarios a test system with the ability to simulate realistic scenarios is required. In this paper we present the implementation of a modular and highly scalable Radar Target Simulator, which is capable to simulate multiple independent moving targets with realistic parameters.

Cambridge University Press eBooks, Feb 17, 2010

International Journal of Rf and Microwave Computer-aided Engineering, Jul 6, 2009

... 3.0 スペイン Attribution-NonCommercial-NoDerivs 3.0 Spain Atribución-NoComercial-SinDerivadas 3.0... more ... 3.0 スペイン Attribution-NonCommercial-NoDerivs 3.0 Spain Atribución-NoComercial-SinDerivadas 3.0 España Attribution-NonCommercial-NoDerivs 3.0 Spain Reconocimiento-NoComercial-SinObraDerivada 3.0 España Uveďte autora-Neuívejte dílo komerčně-Nezasahujte ...

Most of the modern cars are equipped with au-tomotive radar sensors. These are important componen... more Most of the modern cars are equipped with au-tomotive radar sensors. These are important components of advanced driver assistance systems (ADAS). Over-the-air (OTA) stimulation of the radar sensor can be used to realize testing of such systems on a test-rig for ready-to-drive cars; many radar target stimulators (RTS) enable OTA testing. Most state-of-the-art RTS are only capable of generating point targets. Unlike point ones, the real radar targets look more like target clouds. In this paper we discuss a novel concept to create more realistic synthetic radar targets with reasonable effort utilizing RTS.