Showing papers on "Front-to-back ratio published in 2007"

1-D Scanning Arrays on Dense Dielectrics Using PCS-EBG Technology

Abstract: We show how the design of integrated arrays can significantly benefit from planar circularly symmetric (PCS) electromagnetic band gap (EBG) structures. Using this technology, a phased array that scans up to 40deg in one dimension and that is characterized by relatively large bandwidth (BWap15%) is designed, manufactured and tested. The specific advantages coming from the use of PCS-EBGs are two fold. On one hand the losses associated to surface waves are significantly reduced. On the other hand each element of the array has a larger effective area that leads to a higher gain for the complete array when compared with a standard technology. Additional benefits are the low cross-polarization levels, the good front to back ratio considering that the antenna does not include a backing reflector, and the low profile

Design of a Yagi-Uda antenna by simulated annealing for gain, impedance and FBR

Abstract: A method of using simulated annealing algorithms to optimize the element spacing and lengths of Yagi-Uda antennas is presented Simulated Annealing (SA) is a powerful stochastic global search and optimization method It converges asymptotically probabilistically to a global optimum Yagi-Uda antennas gain is highly sensitive and depend upon numerous parameters and therefore it is difficult to optimize We present a simulated annealing algorithm-based automated antenna optimization system that uses the length and space between elements as optimization variables Our results include Yagi-Uda antennas that have excellent gain, impedance and front to back ratio properties

Modelling and Characterisation of a Compact Sensor Antenna for Healthcare Applications

Abstract: The paper presents a planar compact antenna structure used in sensors aimed at healthcare applications. Antenna performance is numerically investigated with regards to impedance matching, radiation patterns, gain and efficiency. The compact size of the sensor causes the antenna to be susceptible to variable changes caused by the presence of lumped components. The study illustrated the importance of including full sensor details in determining and analysing the antenna performance. The body-worn sensor performance is also demonstrated and effects on antenna parameters are analysed, specifically radiated power, efficiency and front to back ratio of radiated energy. Radio propagation characterisation of the sensor operation in stand alone and on-body scenarios are introduced. Improvements are necessary in antenna design, matching circuitry and also sensor layout for better coverage and for obtaining maximum achievable communication range to produce efficient and reliable medical telemetry and monitoring systems.

Air-fuel ratio control system for internal combustion engine

Abstract: When detecting the data showing an output characteristics of an air-fuel ratio sensor, the air-fuel ratio (feed air-fuel ratio) supplied to each cylinder is alternately changed to rich or lean by a predetermined ratio (X %). And then, the average value of the detected air-fuel ratio λ in the rich side and the lean side is respectively computed. A ratio between the variation width of the air-fuel ratio and the detection variation of the air-fuel ratio sensor 20 is computed as an output-characteristics correction value for correcting the dispersion in the output characteristics of the air-fuel ratio sensor. By correcting the air-fuel ratio detection of the air-fuel ratio sensor with this output-characteristics correction value, the dispersion in the output characteristics due to manufacturing tolerances, aged deterioration, etc. of the air-fuel ratio sensor is corrected.

Design and development of a novel compact soft-surface structure for the front-to-back ratio improvement and size reduction of microstrip yagi antenna arrays

Abstract: A new soft surface (SS) configuration is proposed that can improve the front-to-back (F/B) ratio significantly while maintaining a high gain for any planar antenna array In addition, the size of this array-including the finite substrate dimensions - has been reduced in comparison to the non-SS design's size As a benchmark, the proposed SS structure is implemented to the printed microstrip Yagi array design proposed in to achieve a new design with a higher gain and a compact size, that was analyzed for different ground sizes around 58 GHz It is observed that an improvement of at least 3 dB in the F/B ratio and of at least 1 dBi in gain are obtained Experimental results verify the claims presented in this paper

Design of PBG in the square patch with truncated corners microstrip antenna

Abstract: A new PBG structure for the square patch with truncated corners microstrip antenna is presented.The probe-fed patch is surrounded by some etched square patches which are shorted to the ground.Simulation and experimental results show that this HIGP structure can improve the front to back ratio and the gain,meanwhile the circularly polarization performance is maintained.