Mario Leib

Design and characterization of a UWB slot antenna optimized for radiation in human tissue

Ultra-wideband (UWB) short-range communication systems are valuable in medical technology, particularly for implanted devices, due to their low power consumption, low cost, and high-data rates. Hence, antennas suitable for implantation in the human body are desired. The focus of this publication is on the design of a small planar UWB slot antenna, optimized for operation in human tissue. The antenna is fed by a triplate line and operates in the frequency range 3.1GHz-10.6GHz. The characterization of the antenna is performed in selected tissue mimic liquids, and the obtained radiation diagram shows a desired uniform characteristic over frequency. The measured mean antenna gain is 3.8 dBi. Besides the antenna design, the general properties of human tissue, the lossy phantom liquids, and the measurement setup for the radiation in human tissue are briefly discussed within this paper.

Highly compact impulse UWB transmitter for high-resolution movement detection

In this paper the hybrid integration of an FCC-compliant fifth-order Gaussian derivative impulse generator IC together with a compact ultra-wideband Vivaldi antenna is presented. The setup results in a compact FCC-compliant impulse UWB transmitter. Measurements of the impulse shape in time and spectral domain are shown. With this transmitter a movement detection and the precise measurement of the movement deviation value by a correlation measurement technique is presented. This shows the ability of the UWB radar system to operate as a movement detection sensor. The measurements include a breath rate measurement of a human being.

A Compact Ultra-wideband Radar for Medical Applications

In this article an impulse based radar system operating in the ultra-wideband frequency range between 3.1 GHz and 10.6 GHz is presented. The radar sensor is intended to be used in medical diagnostics. In principle the realized radar could be applied to various applications, especially due to the compact overall size and the size of the radar front-ends in particular. One focus of the paper is on a detailed description of the system architecture with the correlation receiver and the time delay adjustment using a variable phase setting for the trigger signals. Furthermore, the key components of the radar, the monolithically integrated pulse generator and the planar antenna, are explained. The capabilities of the radar and the correlation principle are shown in different validation measurements, where a metal plate is used as an ideal target. In addition, two different methods for movement detection were demonstrated successfully measuring the respiration and the heart beat of a test person. Index Terms – pulse radar, ultra-wideband, correlation receiver, medical diagnosis

A novel ultra-wideband circular slot antenna excited with a dipole element

In this contribution, a novel differentially-fed planar ultra-wideband antenna is presented and discussed in detail. This antenna is intended to operate in the FCC frequency range from 3.1GHz to 10.6GHz. It is composed of a circular aperture in ground plane and a broadband dipole element exciting the slot aperture. This combination leads to an outstanding radiation performance with a quite uniform radiation pattern over frequency and a mean gain of 2.9 dBi. The measured return loss of the realized antenna is better than 10 dB from 3.9GHz to 9.8GHz including an inevitable balun for characterization, and without the balun the 10 dB bandwidth is extended to 3.4GHz–11GHz according to the simulation results. Besides the characterization of the antenna in frequency domain, the time domain behavior is shown and demonstrates the antennas capability for impulse based UWB radio.

An Ultra-Wideband Dielectric Rod Antenna Fed by a Planar Circular Slot

A novel ultra-wideband (UWB) dielectric rod antenna fed by a planar structure is presented. The planar structure consists of a circular slot antenna supplied by a dipole. This planar antenna excites the HE11 mode of an attached circular dielectric rod. Due to this combination, a broadband and low-dispersive overall antenna performance is achieved. Furthermore, an additional reflector at the backside of the antenna increases the directivity. With this configuration, a return loss better than 10 dB from 3.5 to 11.8 GHz is achieved with a nearly constant gain and a mean gain of 8.7 dBi. Beside the standard characterization, the system performance of the antenna is evaluated by means of the fidelity factor calculated from time-domain measurements and applying a UWB impulse generator.

An ultra-wideband vertical transition from microstrip to stripline in PCB technology

An ultra-wideband transition from microstrip to stripline in PCB technology is presented applying only through via holes for simple fabrication. The design is optimized using full-wave EM simulations. A prototype is manufactured and measured achieving a return loss better than 8.7dB and an insertion loss better than 1.2 dB in the FCC frequency range. A meander-shaped delay line in stripline technique is presented as an example of application.

A microstrip-fed ultra-wideband slot antenna

Due to the split of the main beam above 9 GHz the antenna cannot operate in the complete FCC frequency range from 3.1 GHz to 10.6 GHz, but is a well suited candidate for the ECC band from 6 GHz–8.5 GHz.

A symmetrically fed aperture-coupled stacked-patch antenna

Although the proposed antenna does not completely fulfill the10 dB matching requirement of the ECC UWB band entirely, it qualifies itself as a good candidate for UWB applications requiring radiation to one side only. The antennas high gain makes it suitable for directional radio systems, e.g. in the medical field for communication with a pacemaker implant. For this purpose, further investigations have to focus on downsizing the whole antenna structure as well as on optimizations for radiating into human body tissue.

A multilayer front-end for an imaging radar sensor

In this contribution, a compact multilayer front-end for a 24 GHz FM-CW imaging radar sensor is presented. After a brief review of the sensor concept the front-ends design and realization are described. The front-end consists of one transmitter stage followed by a switched transmit array with 25 antenna elements and two nonswitched coherent receivers. Key structures of the multilayer printed circuit board (PCB) design are the contacting areas of MMICs, space saving RF feed-throughs and the antenna. Solutions for these structures are presented in detail together with exemplary test results. Successful realization and tests demonstrate that a front-end module for an electronically scanning sensor can be realized in multilayer PCB technology at moderate cost.

In-Phase and Anti-Phase Power Dividers for UWB Differentially Fed Antenna Arrays

This letter presents two novel power dividers operating in the FCC frequency range from 3.1 to 10.6 GHz. The two outputs of each power divider are coplanar striplines, while the input is a microstrip line. Hence, the power dividers act as baluns and are suited for differentially fed antennas. The in-phase version shows a return loss of better than 15 dB from 1 to 12.3 GHz, whereas for the anti-phase version the return loss is better than 10 dB from 1 to 12.3 GHz. Besides the characterization of the dividers, a linear antenna array fed by one of the dividers is shown, and measurement results in the time domain and frequency domain are presented. The mean gain of the realized four-element array is 9.7 dBi.