ELECTRONIC INDUSTRIES
Year:2011 | Volume:2 | Issue:3 (7)|Papers Count:6

This paper presents a rigorous and comprehensive method for retrieving the electromagnetic constitutive parameters of a slab of metamaterial from the measurement or numerically calculation of scattering parameters. The main problem in this process is the doubtfulness exists in the phase of the transmitted field or the correct branch of logarithmic function appears in relevant equations. The novelty introduced here is on applying the Kramers-Kronig(K-K) relation to the imaginary part of refractive index and therefore obtaining its real part with less ambiguity. In Addition, by means of the mentioned approach one can obtain full retrieval results even where the imaginary part of electric permittivity or magnetic permeability becomes negative. Indeed, this method can be applied to an extensive range of materials independent of their operational frequency.

This paper presents a novel architecture for implementing of Payload Control and Data Acquisition Sub System in the space missions. Monitoring and Data Acquisition from Different payloads in the satellites is one of important activities which plays vital role in maintaining of space missions. PCDAS collects all required data from other satellite sub systems and Prepare transmitting of the data to the ground station after data formatting according the existing standards such as CCSDS. The data synchronization and coordination with the on board computer of satellites and satellite’s communication sub system is very important for PCDAS. In this paper a new architecture for PCDAS is presented to act from satellite on board computer independently, so the satellite's on board computer processing volume is reduced drastically. For presenting this novel architecture the new hardware configuration method that called dynamic partial reconfiguration is used. At the end of this paper proposed architecture is written in VHDL standard language and it is simulated and synthesized with ISE software. Finally proposed architecture implemented on the virtex-4 FPGA from Xilinx Company and desired results is presented.

One of the most important subjects in the productivity of the satelliteis its guiding, controlling and tracking by ground stations. The satellite trajectory simulator is one of the tracking requirements in the ground station control unit. The satellite trajectories due time are undergone by various disturbances. This paper presents necessary formula using SGP algorithm and models the necessary calculation to simulating the disturbance effect on the orbit. The purpose of this paper is, error analyzing of this model with J2 model and two-body modelduring the third week. Error analysis and experimental test results using this algorithm show that the tracking accuracy of antenna with the 40 beam during this time is acceptable.

In this paper, we have investigated GaN/A1GaN Modified Quantum Dot (MQD) nanocrystal and GaN/ A1GaN/GaN/ A1GaN Quantum Dot- Quantum Well (QDQW) heteronanocrystal which has been analyzed by the Finite Element Numerical Methods (FEM). Simulations carried out for state n= 1, 1=0, and m=0 which are original, orbital, and magnetic state of quantum numbers. The effects of variation of radius layers such as total radius, GaN core, shell, and A1GaN barriers radius on the wavelength and emission coefficient are studied. Furthermore, window of 330-410 nm wavelength detected by these structures, provides us facility to detect the light of UV solidstate lasers that are in 349, 351, 355 and 375nm wave length. These suggested structures can be used for medicine, telecommunications and computing (optical storages).

In this paper, according to the size of the transistors and the feedback gain of the oscillator, a design point in which the gain of the active core of the oscillator is maximum, is derived. In order to realize the feedback gain, we utilize a transformer. This transformer is employed in such a way that it could be able to provide the feedback gain for the oscillator and also eliminate the large portion of parasitic capacitance, simultaneously. By using this technique, the phase noise at 1MHz offset and the tuning range in comparison with the general transformer oscillator is improved by 5dB and 70% respectively. Furthermore, we show that with linearization of the oscillator in millimeter-wave frequencies, phase noise of the oscillator can also be reduced even more. Regarding this criteria we linearize the oscillator as much as possible. Post-simulation results show that the circuit designed in 0.18-μm CMOS technology, consumes 43mW while showing -89dBc/Hz phase noise at 1MHz offset with 1.9GHz tuning range around 57GHz.

In this paper we analyze the security of SEAS protocol. The only security goal of this protocol is to authenticate the RFID tag to the RFID reader which, in this paper, we show that the protocol does not satisfy this property. Hence, we do not recommend this protocol to be employed in any application. In this paper we present a tag impersonation attack against it. Tag impersonation attack is a forgery attack in which the reader authenticates the attacker as a legitimate tag. Our tag impersonation attack’s success probability, which is the first attack against the SEAS protocol to the best of our knowledge, is “1” and its complexity is only two runs of protocol.