UHF SATCOM broadband CP antenna: moxon type bent-dipoles over a ground plane

In this paper, we investigate and compare two different antenna types for UHF SATCOM applications; proposed Moxon type (bent dipole) and conventional egg beater (loop) antennas in terms of antenna performance and physical size. Bent dipole and egg beater antennas are simulated using HFSS software. Prototype antenna for Moxon type is also fabricated and measured for its return loss using Agilent network analyzer and compared to that of an egg beater antenna. Antenna gains are also simulated. Simulation results show that Moxon type antenna has more impedance bandwidth than egg beater antenna with smaller dimensions and hence can be used for broadband SATCOM applications

A 4.5-5.8 GHz Differential LC VCO using 0.35 m SiGe BiCMOS Technology

In this paper, design and realization of a 4.5-5.8 GHz, Gm LC voltage controlled oscillator (VCO) for IEEE 802.11a standard is presented. The circuit is implemented with 0.35´m SiGe BiCMOS process that includes high-speed SiGe Heterojunction Bipolar Transistors (HBTs). A linear, 1300 MHz tuning range is measured with accumulation-mode varactors. Fundamental frequency output power changes between -1.6 dBm and 0.9 dBm, depending on the tuning voltage. The circuit draws 17 mA from 3.3 V supply, including buffer circuits leading to a total power dissipation of 56 mW. Post-layout phase noise is simulated -110.7 dBc/Hz at 1MHz offset from 5.8 GHz carrier frequency and -113.4 dBc/Hz from 4.5 GHz carrier frequency. Phase noise measurements will be updated in the final manuscript. The circuit occupies an area of 0.6 mm2 on Si substrate including RF and DC pads

A 77 GHz on-chip strip dipole antenna integrated with balun circuits for automotive radar

In this paper, design and implementation of a 77 GHz on-chip strip dipole antenna integrated with both lumped and transmission line based balun circuits are presented. The on-chip antenna is realized by using IHP’s 0.25 μm SiGe BiCMOS technology with localized back-side etch (LBE) module to decrease substrate loss. The strip dipole antenna is fed by both a lumped LC circuit and strip line tapered baluns integrated on the same substrate and occupies an area of 1x1.2 mm2 including the RF pads. For increased directivity, the antenna sits on a grounded silicon substrate. Experimental results show that antenna is well matched around the design frequency and achieves 7 GHz impedance bandwidth (minimum return loss of 17 dB) for the LC balun circuit. The antenna and its feeding structure are well suited for 77 GHz single chip automotive radar applications

Microstrip patch antenna array for range extension of RFID applications

In this paper, an UHF band 2X2 microstrip phased antenna array is designed for extending the range of an RFID reader system. The phased antenna array operates at the frequency of 867 MHz, as specified in Gen2 protocol European standards. The phased antenna array has four microstrip patch antennas, three Wilkinson power dividers and a transmission line phase shifter printed on the same Arlon AD450 substrate with a dielectric constant of 4.5 with dimensions of 34x45 cm. The phased array antenna has a measured directivity of 9.5 dB and the main beam direction can be switched between the angles of ± 40 degrees with a 3dB beamwidth of 90 degrees. The phased antenna array can be used to extend the RFID system working range

RFID coverage extension using microstrip-patch antenna array

In this paper, a UHF-band 2 x 2 microstrip phased-array antenna is designed and implemented to extend the coverage of an RFID reader system. The phased-array antenna has four microstrip-patch antennas, three Wilkinson power dividers, and a transmission-line phase shifter. These are printed on a dielectric substrate with a dielectric constant of 4.5. The array has dimensions of 34 cm x 45 cm, operating at a frequency of 867 MHz, as specified in RFID Gen2 protocol European standards. The phased-array antenna has a measured directivity of 12.1 dB, and the main-beam direction can be steered to angles of +/- 40 degrees, with a HPBW of 90 degrees. The phased-array antenna is used as the receiving antenna in a commercial reader system. Experimental results indicate that the coverage of the RFID system with the phased-array antenna is superior to the coverage with a conventional broader-beamwidth microstrip-patch antenna. The proposed system can also be used for a wireless positioning system

Building a Truly Distributed Constraint Solver with JADE

Real life problems such as scheduling meeting between people at different locations can be modelled as distributed Constraint Satisfaction Problems (CSPs). Suitable and satisfactory solutions can then be found using constraint satisfaction algorithms which can be exhaustive (backtracking) or otherwise (local search). However, most research in this area tested their algorithms by simulation on a single PC with a single program entry point. The main contribution of our work is the design and implementation of a truly distributed constraint solver based on a local search algorithm using Java Agent DEvelopment framework (JADE) to enable communication between agents on different machines. Particularly, we discuss design and implementation issues related to truly distributed constraint solver which might not be critical when simulated on a single machine. Evaluation results indicate that our truly distributed constraint solver works well within the observed limitations when tested with various distributed CSPs. Our application can also incorporate any constraint solving algorithm with little modifications.Comment: 7 page

The effect of time on ear biometrics

We present an experimental study to demonstrate the effect of the time difference in image acquisition for gallery and probe on the performance of ear recognition. This experimental research is the first study on the time effect on ear biometrics. For the purpose of recognition, we convolve banana wavelets with an ear image and then apply local binary pattern on the convolved image. The histograms of the produced image are then used as features to describe an ear. A histogram intersection technique is then applied on the histograms of two ears to measure the ear similarity for the recognition purposes. We also use analysis of variance (ANOVA) to select features to identify the best banana wavelets for the recognition process. The experimental results show that the recognition rate is only slightly reduced by time. The average recognition rate of 98.5% is achieved for an eleven month-difference between gallery and probe on an un-occluded ear dataset of 1491 images of ears selected from Southampton University ear database

A 77GHz on-chip microstrip patch antenna with suppressed surface wave using EBG substrate

This paper presents the design of a patch antenna with suppressed surface waves by means of applying an electromagnetic band-gap structure. Establishing th e antenna on high dielectric substrate such as Silicon makes it possible to integrate the antenna with RFIC active component and circuitry. However, the performance (gain and radiation pattern) of antenna will be degraded due to the presence of surface waves on a thick dielectric substrate. It is possible to des ign an engineered substrate that filters out the surface wave around the frequency of interest. Moreover, having high dielectric substrate will localize EM wave to substrate and hence reduce antenna gain. For this problem, available silicon etching technology is used to remove the substrate right under the patch and have a locally low dielectric constant substrate underneath the antenn a. Proposed microstrip antenna resonates at 77GHz with 7dB realized gain which can be used in array for Automotive Radar purposes. Simulation results show great improvement in radiation pattern and 3dB increase in antenna's broadside gain in comparison with antenna on normal substrate

Competition, non-financial measures and the effectiveness of management control system

This paper reports the results of an empirical study examining the relationship between the emphasis on non-financial measures and two other variables; the intensity of competition and the effectiveness of a management control system, in a manufacturing company. Two important issues focused in the study are: does competition compel managers to utilize more non-financial measures in decision making and is the emphasis given to non-financial measures worthwhile? Data from 105 manufacturing companies throughout Malaysia were analyzed using correlation and regression analysis. The results of both analyses indicate that the emphasis given to non-financial measures in decision making has a positive correlation with the effectiveness of a management control system and secondly, the intensity of competition faced by an organization is positively correlated with the emphasis on non-financial indicators. Descriptive analysis was also performed to evaluate the distribution of emphasis on non-financial measures by the age, location, ownership, size of an organization and its industry