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The (ESTO) selective fading phenomena associated with speed digital systems using higher level QAM, QPSK and PSK signals are investigated by taking into account the physical model of the layered troposphere. Conditions of weak and strong either surface or elevated ducts are investigated.
Millimetre wave techniques combined with optical techniques are being employed to provide an operational technology for the future mobile communication Systems. The research group of Microwaves and Fibre Optics of DECE/NTUA is working on:
New type coils to provide better imaging resolution in MRI systems are being investigated and constructed. A novel type low cost network analyser to be installed in MRI systems have been developed. Research is being carried out towards the development of phased array MRI receiver system.
Inverse electromagnetic techniques are being used to develop diagnostic techniques by measuring evoked potentials. In this context a 16 channel parallel data acquisition system incorporating a reconstruction software programme has been developed. Imaging of brain charge distribution and their movement seems to be a highly useful diagnostic technique.
A Mobile antenna to be used on the car rooftops are being developed. A Spiral geometry, inherently being circularly polarised, is employed. Control of the elevation pattern is achieved by using a parasitic loop or/and high dielectric constant substrate.
In the framework of the Esprit GPMIMD project a neural network model using a realistic differential equation model is employed to observe fundamental brain functions Such Niao, P300 evoked potentials components. Parametric studies by varying synoptic connections and neural network properties are carried out. Both high frequency (EEG) and low frequency hidden evoked potential wave forms are simulated.
A microwave (432 MHz) interstitial system is being Constructed. The system consists of 10 coherent channels with independent amplitude control. The system is fully computer controlled and monitored. Advance hardware and software techniques are employed to construct the system.
Signal processing circuits such as Clock Carrier recovery and amplifier circuits are being designed using H-MDS design software tool. Presently these MMIC'S are being constructed by ITE (Crete).
In order to compute the electromagnetic field induced inside the human body from near field hyperthermia applicators an E-field integral equation techniques is being employed. The distribution of the complex permittivity is taking into account with an accuracy of 5 mm. A method of moments technique with improved accuracy is employed to solve numerically the boundary value problem. To this end a conjugate gradient technique is being employed to salve equations as large as 100.000 Presently the serial code is being ported to a parallel processing transputer based Parsytec CGel-512 Systems The program is being modified to compute conductive or dielectric electromagnetic Structures.