Dragos Dancila

Field operational testing for safety improvement of freight trains using wireless monitoring by sensor network

Today, the majority of wagon failures on railroad systems are because of the poor maintenance of ball bearings, which causes emergent stops and delays. The existing stationary detectors, lack in predicting failures which cause troubles in scheduling maintenance. During the fall of 2011, a trial was performed by applying a wireless sensor network (WSN) aboard a train wagon with the objective to demonstrate a proof of concept for monitoring the temperature of ball bearings aboard the train wagon. This trial investigates several key aspects when applying sensor networks such as radio wave propagation, energy scavenging and performance of the WSN aboard the wagon. Two wireless links were used in the WSN. The aboard network communicates at 2.45 GHz, and the external communication is an 868 MHz radio frequency identification radio link. Since the energy in the WSN node is limited, appropriate energy scavenging devices are also presented and evaluated in a lab environment. Effort has been made to overcome these problems. The energy consumption in the network is still a problem; the most promising energy scavenging technique is piezoelectric harvesting by vibrations, which in the experiments scavenged 2.32 mW.

Design and experimental evaluation of compensated bondwire interconnects above 100 GHz

Different types of bondwire interconnect for differential chip-to-antenna and single-ended chip-to-chip interfaces are investigated. Two differential compensation structures for various lengths of ...

High performance transmit/receive modules in 0.13 um SiGe:C BiCMOS for short range F-band MIMO radars

Transmit and Receive (TX/RX) F-band radar modules are presented. Both modules are implemented in a state of the art SiGe:C BiCMOS featuring high-speed HBTs with fT/fmax of 300/500 GHz. The TX is based on a frequency octupler that consists of a cascade of three Gilbert cells, covering the upper F-band from 120-140 GHz and providing differential output power of up to 6 dBm, the highest values reported to date for BiCMOS. The RX uses the identical frequency octupler followed by a mixer, transformer and a differential LNA, giving altogether conversion gain of 25 dB. Both chips are packaged and connected to off-chip patch antennas using bondwire interconnects with dedicated compensation structures. Initial measurement trials proved full functionality of the realized frontend across 114-152 GHz. It has also been demonstrated that wire-bonding, when properly designed, is still an attractive solution for chip to antenna interconnects even above 110 GHz.

Wireless data transfer with mm-waves for future tracking detectors

Wireless data transfer has revolutionized the consumer market for the last decade generating many products equipped with transmitters and receivers for wireless data transfer. Wireless technology opens attractive possibilities for data transfer in future tracking detectors. The reduction of wires and connectors for data links is certainly beneficial both for the material budget and the reliability of the system. An advantage of wireless data transfer is the freedom of routing signals which today is particularly complicated when bringing the data the first 50 cm out of the tracker. With wireless links intelligence can be built into a tracker by introducing communication between tracking layers within a region of interest which would allow the construction of track primitives in real time. The wireless technology used in consumer products is however not suitable for tracker readouts. The low data transfer capacity of current 5 GHz transceivers and the relatively large feature sizes of the components is a disadvantage.Due to the requirement of high data rates in tracking detectors high bandwidth is required. The frequency band around 60 GHz turns out to be a very promising candidate for data transfer in a detector system. The high baseband frequency allows for data transfer in the order of several Gbit/s. Due to the small wavelength in the mm range only small structures are needed for the transmitting and receiving electronics. The 60 GHz frequency band is a strong candidate for future WLAN applications hence components are already starting to be available on the market.Patch antennas produced on flexible Printed Circuit Board substrate that can be used for wireless communication in future trackers are presented in this article. The antennas can be connected to transceivers for data transmission/reception or be connected by wave-guides to structures capable of bringing the 60 GHz signal behind boundaries. Results on simulation and fabrication of these antennas are presented as well as studies on the sensitivity of production tolerances.

Low Phase Noise Oscillator at 60 GHz Stabilized by a Substrate Integrated Cavity Resonator in LTCC

In this letter, we report a low phase noise oscillator exhibiting state-of-the-art phase noise characteristics at 60 GHz. The oscillator is stabilized by an off-chip substrate integrated waveguide (SIW) cavity resonator, manufactured in LTCC technology. The area on top of the cavity resonator is used to flip-chip mount the MMIC, realized in SiGe technology. Measured oscillators discussed in this paper operate at frequencies of 59.91, 59.97, and 59.98 GHz. The measured phase noise at 1 MHz offset is -115.76 dBc/Hz, -115.92 dBc/Hz and -116.41 dBc/Hz, respectively. To our knowledge, the present hybrid oscillator has the lowest phase noise and highest figure of merit of integrated oscillators at V-band. The simulations are in very good agreement with the measured oscillation frequencies.

Millimeter wave silicon micromachined waveguide probe as an aid for skin diagnosis – results of measurements on phantom material with varied water content

More than 2 million cases of skin cancer are diagnosed annually in the United States, which makes it the most common form of cancer in that country. Early detection of cancer usually results in less extensive treatment and better outcome for the patient. Millimeter wave silicon micromachined waveguide probe is foreseen as an aid for skin diagnosis, which is currently based on visual inspection followed by biopsy, in cases where the macroscopical picture raises suspicion of malignancy.

Design and test results of a wideband sige detector and on-chip slot antenna for W-band sensing applications

This paper presents the circuit designs and results of a wideband power detector and an on-chip slot antenna fabricated in a 0.25 μm SiGe BiCMOS process. The W-band SiGe detector has close to 20 GHz of operational bandwidth (s11≤-10 dB at 75-92 GHz) and a responsivity of 3-5kV/W (NEP = 10-16 pW/Hz1/2) at 83-94 GHz. The SiGe on-chip slot antenna design covers a wide bandwidth (70-110 GHz) with 2 dBi of simulated gain at 94 GHz. The realised wideband SiGe BiCMOS power detector and on-chip antenna are targeting highly integrated single-chip RF front-ends for broadband sensing applications up to 110GHz.

57–64 GHz seven-pole bandpass filter Substrate Integrated Waveguide (SIW) in LTCC

This paper presents the design and characterization of a Substrate Integrated Waveguide (SIW) filter, with a large bandwidth of 7 GHz, designed to cover the unlicensed frequency band, 57–64 GHz. The filter, a seven-pole Chebyshev is integrated in Low-Temperature Co-fired Ceramic (LTCC). It is characterized by a measured bandwidth of 11.8% around a central frequency of 59.1 GHz. It presents a low passband insertion loss of 2.4 dB and high stop band insertion loss in the lower and higher band, respectively 50 dB and 30 dB. The filter has a compact size of 9450 × 2100 × 200 µm3.

A megawatt class compact power combiner for solid-state amplifiers

We propose a compact multiport two-stage combiner capable of handling peak power up to 10 MW at the UHF band and suitable for particle accelerator applications. The detailed electromagnetic and thermal simulations of the combiner operating at the ESS specifications of 400 kW at 352 MHz are presented. At the first stage, the power is combined to a 100 kW level by means of a non-resonant 12-way radial combiner, which is assumed to be fed by 8 kW solid-state amplifiers. At the second stage, a waveguide combiner with T-shape couplers separated by a half-wavelength of the fundamental waveguide mode is used in order to bring the combined power to the required level. The combiner is broadband and has a relative power non-uniformity less than 5% over a 10 MHz frequency band around the central frequency. The size of the proposed combiner is several times smaller than the existing ones. We also present low-power measurement results of a prototype of the radial combiner.

RF-MEMS reconfigurable GaAs MMICs and antennas for microwave/MM-wave applications

This paper presents the results of some reconfigurable RF-MEMS switching circuits and antennas fabricated using GaAs MMIC and LTCC based processes. Wafer-level packaged GaAs RF-MEMS series and shunt switches demonstrating low losses (≤ 0.5 dB) up to 40 GHz are presented together with a compact Ka-band GaAs MEMS 3-bit phase shifter circuit and LTCC based array antenna modules. Furthermore, some GaAs MMIC wideband/V-band RF-MEMS switching networks and a W-band on-chip slot antenna design show promising RF properties for broadband mm-wave applications related to wireless communication and RF-sensing.