Marcel D. Blech

A Dipole Excited Ultrawideband Dielectric Rod Antenna With Reflector

A novel very compact ultrawideband dielectric rod antenna with metallic reflector is presented. The desired HE11 mode on the rod is excited by a biconical dipole fed by a broadband tapered microstrip line balun. The input reflection remains below -10 dB from 3 up to 20 GHz. The antenna exhibits a flat gain larger than 7 dBi over the whole ultrawideband frequency range from 3 to 10 GHz approved by the Federal Communication Commission. An almost constant transient performance over a wide azimuth angle of plusmn40deg is obtained with small dispersion.

Concept of an UWB impulse radio B-/QPSK transmitter based on standard logic components

An UWB impulse radio (IR) transmitter comprising of standard emitter coupled logic (ECL) components is presented. It has a variable operating frequency ranging from 2-8 GHz and synthesizes Gaussian shaped B-/QPSK modulated impulses. The pulse width as well as the pulse position is variable in steps of 10 ps. This enables the use of the transmitter for laboratory purposes as test system for different IR modulation schemes including basic B-/QPSK, transmitted reference (TR) and pulse position modulation (PPM).

A Balanced Impulse Radiating Omnidirectional Ultrawideband Stacked Biconical Antenna

A compact symmetric discone antenna for the 3 GHz to 20 GHz frequency range is demonstrated. The antenna design is optimized for a good transient response with low angular dependency. This property reduces antenna distortions and simplifies antenna de-embedding. The design is based on the well-known biconical antenna, which has been radically enhanced with different geometric features. Far field modal analysis has been used for both the development and the verification of the concept that ensures a constant radiation pattern. A prototype of the balanced antenna with an improved feeding mechanism based on two separate discone antennas together with a three-port balun is also presented. Measurements in the time and in the frequency domain have been performed in order to characterize the antenna. Overall, the results show significantly improved impulse responses and input matching compared to a standard biconical antenna. Therefore, the new antenna is very well suited for advanced channel characterization, reference measurements, and system verifications.

Enhanced Parameter Determination of an Empirical UWB Channel Model for European Building Standards

This paper presents ultra-wideband (UWB) indoor propagation channel measurement techniques and results for the parameters of an empirical channel model. To analyze the channel impulse response an improved technique is applied to remove the parasitic effects of the employed hardware properly. The transmission between the ports of a transmit (TX) and receive antenna (RX) is measured with a vector network analyzer (VNA). As the impulse responses of the antennas are deconvolved from the measurements, the channel transfer function in the frequency range of 2-8 GHz can be determined. This approach is applicable as omnidirectional antennas with almost angularly independent impulse responses are used. A statistical model is employed, based on a large database measured in a commercial indoor environment. The measurements include line-of-sight (LOS) and non-line-of-sight (NLOS) scenarios, where the distance between the transmitter and receiver is varied from 1-5.5 m. To characterize small-scale and large-scale statistics of the channel, at each receiver position 25 measurements are accomplished over a grid with 5×5 spatial points.

Time-Domain Spherical Near-Field Antenna Measurement System Employing a Switched Continuous-Wave Hardware Gating Technique

A time-domain spherical near-field antenna measurement system capable of gating out erroneous signal components, which arise due to multipath propagation in nonideal anechoic chambers, is presented. The developed hardware (HW) gating technique evaluates a switched sinusoidal signal, which is synthesized by an application-specific pulse generator and acquired by either a commercial real-time digitizing oscilloscope or an application-specific equivalent-time sampling receiver developed for this particular purpose. The low-cost measurement system has been optimized for acquisition speed, dynamic range, and resolution. Its operating frequency range covers 1.5-8 GHz, and it is applicable to antennas exhibiting a typical 3-dB bandwidth in excess of 400 MHz. Test measurements of an omnidirectional and a directional antenna, respectively, have been carried out to demonstrate the performance of the novel HW gating technique. It is shown that the HW gating technique can significantly improve the absolute average deviation of the erroneous 3-D far-field pattern.

Microwave telemetry in high speed machine tools

The paper describes the development of a complex antenna system for data communication between the rotating and static part inside a spindle system of a machine tool with revolutions per minute up to 40000 RPM. The system is based on the transponder technology where power is induced via closed coupled coils to the rotating part and data is sent back wireless at 2.4GHz to the static part. To maintain a stable and lossless data communication, it is necessary to achieve a circular horizontal diagram of the antenna array and to consider the nearfield conditions and the complex CAD data of the metallic and dielectric structures of the whole assembly, causing strong reflections, diffraction and refraction. This is done by a three-dimensional full-wave analysis of the device under consideration of all these effects. By optimization of the whole structure no bit errors occurred with full rotational speed within weeks.

2-dimensional ultra-wideband monopulse based direction finding

A novel ultra-wideband (UWB) 2-dimensional angle of arrival (AOA) estimation technique is presented. Using a planar arrangement of one dielectric monocone antenna surrounded by four dielectric rod antennas all exhibiting an almost frequency independent beam pattern in the range of 2–4 GHz, precise 2-dimensional direction finding based on the amplitude monopulse principle is applicable. Thereby an average absolute angular error of 2° in a range of ±50° in both ϑ and ρ is achieved. Using two auxiliary dielectric rod antennas time difference of arrival (TDOA) based direction finding can also be employed, whereas the array dimensions can be kept very compact.

Ultra-Wideband dielectric rod antenna with biconical dipole and reflector

A directive ultra-wideband (UWB) antenna exhibiting a gain of more than 7 dBi in the whole FCC UWB frequency band is presented. The excitation of the so called dipole mode on the rod is achieved by a biconical dipole. Placing this configuration in some distance to a reflector results in a flat gain curve. Besides an input reflection of -10 dB from 3 up to 20 GHz, this novel antenna has an excellent transient behavior over a wide azimuth angle, whereas the dimensions can be kept very compact.

A Directive Ultra-Wideband Dipole Antenna with Dielectric Rod and Reflector

A directive ultra-wideband (UWB) antenna exhibiting a gain of more than 7 dBi in the whole FCC UWB frequency band is presented. The excitation of the so called dipole mode on the rod is achieved by a biconical dipole. Placing this configuration in some distance to a reflector results in a flat gain curve. Besides an input reflection of better than -10 dB from 3 up to 20 GHz, this novel antenna has an excellent transient behavior over a wide azimuth angle, whereas the dimensions can be kept very compact.