Alexander Koelpin

The Six-Port in Modern Society

Modern wireless sensing and communication systems are often based on high bandwidth and high carrier frequencies. In the range beyond 100 GHz, common receiver architectures, like active homodyne or heterodyne receivers, have an issue with the amplification needed for mixing. Also, high bandwidth is a problem for these systems. In this context, the six-port receiver is a good alternative, just as well as for lowvolume markets. The six-port concept is based on the additive superposition of the two RF input signals using four different relative phases leading to constructive or destructive interaction. The resulting signals are directly downconverted to baseband by diode circuits operated in detector or mixing mode. The complexvalued information can be easily reconstructed from the four baseband voltages. Historic evolution leads from the reflectometer approach for an alternative vector network analyzer to receivers for sensing and communications. A recent topic is the technology gap in automotive workshops for adjusting the long-range radar sensor of a car. Here, the six-port concept as alignment tool is a good choice, because of its excellent phase resolution. Currently, the integration of the six-port receiver on a MMIC for frequencies beyond 100 GHz is the focus of current work and will be intensified in the future. Will the six-port concept replace common active homodyne and heterodyne receivers? No, but it is a serious alternative for millimeter-wave frequencies and ultrahigh-bandwidth applications in wireless sensing and communication systems. This modern concept can tap new markets for both wireless sensors and sensor networks.

Promise of a Better Position

Industrial automation today is an essential technology underlying our modern society. Advanced positioning and sensor feedback tasks in automation processes often require distance displacement detection, e.g., to measure and track the movement of robots. Furthermore, the detection of mechanical stress in complex industrial machinery through an accurate vibration analysis is often a task of major interest. Therefore, high-resolution distance measurements with short- and long-range positioning are important for a large number of sensing applications and can also be used as a precondition for vibrometer applications. Several automation technologies rely on high precision positioning sensors to track linear as well as rotational movements of various machinery.

Six-Port Radar Sensor for Remote Respiration Rate and Heartbeat Vital-Sign Monitoring

A novel remote respiration and heartbeat monitoring sensor is presented. The device is a monostatic radar based on a six-port interferometer operating a continuous-wave signal at 24 GHz and a radiated power of less than 3

A six-port interferometer based micrometer-accuracy displacement and vibration measurement radar

\mu\hbox{W}

Employing six-port technology for phase-measurement-based calibration of automotive radar

. Minor mechanical movements of the patients body caused by the respiration as well as hearbeat can be tracked by analyzing the phase modulation of the backscattered signal by means of microwave interferometry with the six-port network. High-distance measurement accuracy in the micrometer scale as well as low system complexity are the benefits of the six-port receiver. To verify the performance of the system, different body areas have been observed by the six-port radar. The proposed system has been tested and validated by measurement results.

Robust Resource Allocation for MIMO Wireless Powered Communication Networks Based on a Non-Linear EH Model

Displacement detection and vibration measurements are important requirements for automation and mechanical stress diagnosis in diverse industrial environments. Laser interferometry is a widely used technique for these kinds of measurements since it features high-resolution, wide dynamic range and wide frequency response. Another advantage of the laser interferometry technique is contactless diagnosis/sensing which allows remote operations. However this technique is not suitable in harsh environments for instance with the presence of dust or fog which occur in several industrial production sites. In this paper a new contactless radar based vibration measurement technique is presented. It features an RF frontend based on a passive six-port interferometer working at 24 GHz. A dedicated signal processing unit is also presented. The proposed hardware allows to measure with a position accuracy of 0.5 µm.

Multiport Technology: The New Rise of an Old Concept

Radar technology is today a key feature for the automotive industry and is becoming of greater importance among most car-producers. Its applications range from cruise control, to pre-crash and parking aid systems. Radar units are already being mounted on several automobiles. Such systems employ high-tech devices and state of the art technology, optimized for robustness and reliability. Specific techniques have been developed to build and install radar devices on board of the vehicles. In particular, precise calibration techniques are being used to set the devices and adjust them so to meet the wanted operation requirements. Radar devices used for adaptive cruise control, installed in front of the vehicle to scan the road ahead in the driving path need a particularly fine adjustment to be as reliable as required by the automotive security standards. Calibration issues in nowadays trimming techniques are causing major problems in the employment of such radar systems. In particular, misalignment of the radar cruise control sensor in respect to the driving axis of the vehicle is leading to false interpretations and reading errors. In this paper, a new, innovative and precise calibration technique is proposed to solve the current calibration problems, focusing on a special microwave measurement technique for enhanced accuracy and reliability.

Diode power detector DC operating point in six-port communications receivers

In this paper, we consider a multiple-input multiple-output wireless powered communication network, where multiple users harvest energy from a dedicated power station in order to be able to transmit their information signals to an information receiving station. Employing a practical non-linear energy harvesting (EH) model, we propose a joint time allocation and power control scheme, which takes into account the uncertainty regarding the channel state information (CSI) and provides robustness against imperfect CSI knowledge. In particular, we formulate two non-convex optimization problems for different objectives, namely system sum throughput maximization and the maximization of the minimum individual throughput across all wireless powered users. To overcome the non-convexity, we apply several transformations along with a one-dimensional search to obtain an efficient resource allocation algorithm. Numerical results reveal that a significant performance gain can be achieved when the resource allocation is designed based on the adopted non-linear EH model instead of the conventional linear EH model. Besides, unlike a non-robust baseline scheme designed for perfect CSI, the proposed resource allocation schemes are shown to be robust against imperfect CSI knowledge.

Six-Port Receiver Analog Front-End: Multilayer Design and System Simulation

Modern society has shown a large demand for ubiquitous and wireless connectivity, information transmission with high data rates, and precise sensors for any kind of physical dimension. Nevertheless, the frequency spectrum is limited and bandwidth restricted by regulatory issues. Over the last few years, a continuous rise in operating frequency linked to rising bandwidth has been observed. For short-range operation, the license-free industrial, scientific, and medical (ISM) bands beyond 100 GHz are becoming more a focus for practical applications. At the same time, microwave monolithic integrated circuit (MMIC) processes must keep up with this rise in operating frequency, requiring high investment costs in new MMIC technology. Initially, before the cost of this technology becomes reasonable, alternative hybrid circuit concepts are needed as a door opener for mass-market applications. For this purpose, an old frontend concept is getting increased support, leading to a constant growth of an originally small, but worldwide, community: multiport technology. This article provides an overview of the basics, possible applications, and specific calibration procedures for the six-port circuit, which is the most common multiport implementation of this promising architecture.

A 77-GHz SiGe Integrated Six-Port Receiver Front-End for Angle-of-Arrival Detection

In this paper a diode power detector circuit is investigated for application in a six-port communications receiver. The diode behavior is modeled by the fundamental diode equation, which is solved for the output DC operating point applying an expansion theorem of modified Bessel functions for the exponential function. The results are compared with a Harmonic Balance system simulation and the closely matching results show that the assumptions made to find the numerical solution hold true.