Grzegorz Adamiuk

Basic Properties and Design Principles of UWB Antennas

Basic principles for ultra-wide-band (UWB) radiation are presented and discussed in this paper. The discussion starts with a description of the influence of antennas on UWB transmission. The parameters characterizing antennas in time and in frequency domain are specified. Since the number of possible antenna structures is nearly unlimited, the focus will be on a classification according to different radiation principles. For each of these mechanisms, the typical advantages and disadvantages are discussed, and an example antenna and its characteristics are presented. For a wireless engineer, the problem to solve is the proper design of an antenna with the desired radiation characteristics. The final outcome of this paper is that there exist numbers of UWB antennas, but not each of them is suited for any application, especially in view of radar and communication systems requirements.

UWB Antennas for Communication Systems

Since the U.S. Federal Communications Commission (FCC) opened the spectrum from 3.1 to 10.6 GHz for unlicensed radio applications with an EIRP of up to 41.3 dBm/MHz, numerous papers have been published on ultrawideband (UWB) antennas. Often the goal in these publications is to present an antenna, which has a satisfactory input reflection coefficient and a reasonable, constant radiation diagram versus frequency. However, in the case of UWB, there are numerous additional critical characteristics, which must be considered in the proper wireless system design. The publications, which treat this topic with sufficient proficiency, use such quantities as transient gain, group delay, ringing, dispersion, signal fidelity, polarization, efficiency, and the peak value of the transient response. For practical applications based on signals with an UWB instantaneous bandwidth occupation, all criteria are of vital importance, because they determine the sensor resolution, accuracy, or increase the bit error rate in communications systems. This paper gives an overview of UWB antenna designs together with their suitability for different applications with respect to the aforementioned critical characteristics. Additionally, UWB antenna array design, polarization diversity, and application in body area network (BAN) will be discussed. In nearly all cases the time-domain characteristics are taken into account, as they are more intuitive to interpret and very convenient for time-domain UWB system design.

Compact, Dual-Polarized UWB-Antenna, Embedded in a Dielectric

A compact dual-polarized antenna is described for ultrawideband (UWB) applications. The main features of the antenna, besides an ultrawidebandwidth are low cross-polarization and small dimensions. The feed of the antenna is based on the tapered slot antennas, enclosed in a dielectric. The new antenna concept, including the feed of the antenna for dual-polarization and its integration, is described in detail. Prototypes are shown and their performances are demonstrated, based on simulation and measurement results in frequency and time domain. The antenna prototype input match is better than -10 dB, a maximal gain of 10.5 dBi and a mean polarization decoupling of approximately 17 dB in the main beam direction in the 3.1-10.6 GHz UWB band are achieved. In the time domain a peak value of 0.4 m/ns, a full width at half maximum of 100 ps and a ringing of 145 ps are measured. With a maximum antenna diameter of 35 mm and 53 mm length this new antenna is also suited for UWB antenna arrays.

Dual-Orthogonal Polarized Antenna for UWB-IR Technology

This letter presents a design of a dual-orthogonal, linear polarized antenna for the UWB-IR technology in the frequency range from 3.1 to 10.6 GHz. The antenna is compact with dimensions of 40 times 40 mm of the radiation plane, which is orthogonal to the radiation direction. Both the antenna and the feeding network are realized in planar technology. The radiation principle and the computed design are verified by a prototype. The input impedance matching is better than -6 dB. The measured results show a mean gain in copolarization close to 4 dBi. The cross-polarizations suppression w.r.t. the copolarization is better than 20 dB. Due to its features, the antenna is suited for polarimetric ultrawideband (UWB) radar and UWB multiple-input-multiple-output (MIMO) applications.

Novel Antenna Concept for Compact Millimeter-Wave Automotive Radar Sensors

An antenna concept for compact millimeter-wave radar sensors that desire a fan-beam radiation pattern is proposed. It combines an end-fire antenna on a ceramic substrate with a cylindrical parabolic reflector that can be integrated in the sensors metal housing. The concept allows a direct interconnection from the active components to the antenna in a flip-chip attachment. It is validated with a 77-GHz Yagi-Uda antenna on a 127-mum thick Alumina substrate by measurements with a probe-based measurement setup. The measured return loss, gain, and radiation patterns of the antenna without and with the reflector are given.

Differential feeding as a concept for the realization of broadband dual-polarized antennas with very high polarization purity

In this paper a new concept for the design of the ultra broadband antennas with dual-orthogonal, linear polarization is introduced. It enables an outstanding polarization decoupling over the very wide frequency range. The antenna built accordingly to this concept can be realized in the planar technology, where the radiation occurs perpendicularly to the antenna surface. This feature is not common in the few dual-polarized ultra wideband antennas introduced in the literature. The concept assures that the phase center of radiation is the same for both polarizations and does not move at all in the whole frequency range. This is very advantageous especially for the impulse-based UWB systems. The coupling between ports is very low. The measurements with the antenna basing on this concept confirm the theoretical assumptions and show very good performance of the device.

Planar Yagi-Uda antenna array for W-band automotive radar applications

The use of Radar sensors for driver assistance systems has become widespread in the last years [1]. By now, the focus in the development of automotive Radar sensors mainly lies in the allocated frequency bands at 76 – 77 GHz for Long Range Radar (LRR) [2] and 77 – 81GHz for Short Range Radar (SRR) [3]. To achieve a high angular resolution, Digital Beamforming (DBF) Concepts are expected to be used in future systems [1]. These require a fan-beam radiation pattern with a narrow beam in the elevation plane and a wider beam in the azimuth plane.

Dual-polarized UWB antenna array

The paper describes a dual-polarized antenna array for Impulse Radio Ultra Wideband (IR-UWB) applications. Firstly a brief description of the single radiator is given. Next the prototype is presented and measured data is compared with the simulated one. The linear array consisting of four components achieves a very narrow mean 3 dB beam width, which is approx. 15° in the FCC frequency range from 3.1 GHz to 10.6 GHz. The second main lobe of the array factor and the grating lobes are suppressed by the radiation pattern of the single element. The mean cross-polarization suppression in the main beam direction is larger than 20 dB. Next the simulated and measured time domain radiation properties of the antenna array are presented. The array is applicable in the polarimetric, impulse based ultra wideband systems with high angular selectivity and high range resolution.

Modeling of Mutual Coupling Between Electromagnetic and Thermal Fields in Microwave Heating

This paper presents the analysis and modeling of the mutual coupling between thermal and electromagnetic fields. During the microwave heating process the microwaves are dissipated to heat due to the dielectric losses of the medium. The heat propagation inside the medium depends on its thermal parameters as well as on different propagation mechanisms. In most cases the dielectric properties are dependent on the temperature. In this paper a model is described for a microwave assisted soil decontamination system. The dielectric properties of the soil not only depend on temperature but also on the moisture content which reduces during the heating process. With changing dielectric properties of the soil the electromagnetic field distribution changes as well which again has an influence of the heat propagation. The basic principles of microwave heating and heat propagation are explained in this paper, as well as a simulation model based on an FEM code. To prove the correctness of the model a comparison with measurement results is given.

Polarization diversity in Ultra-Wideband imaging systems

This paper presents an Ultra-Wideband (UWB) indoor imaging system with dual-orthogonal polarized antennas. Both the measurement setup and the algorithm implemented for data processing are introduced. In the presented approach, a 4×1 vertically oriented antenna array is used in order to perform 2D scan. For 3D imaging, single antennas are applied. Emphasis is given to the polarization diversity, through which additional properties of objects such as form, surface structure and orientation are investigated. In this way, some objects are detected, which may remain invisible for single-polarized systems. In addition, the presented approach extends UWB-Radar/Imaging with very high resolution to a high-end system with robust target detection, while providing extensive information about the environment. Such a system can be of great interest in applications such as indoor search-and-rescue operations, motion tracking and indoor navigation.