Ανάπτυξη γενετικού αλγόριθμου για παρασιτικές στοιχειοκεραίες πολλαπλών ενεργών & παρασιτικών στοιχείων
Σταυρούλης, Παναγιώτης Ν.
The usage of multiple antennas, both at transmitters and receivers (MIMO), has been identified as an optimal solution to the system design of wireless networks, mostly due to their major benefits and advantages. In contrast, the usage of MIMO in wireless systems can also increase the requirements for space, power and complexity. Therefore, as a solution to the above problems, the beamspace MIMO technique and the parasitic antennas ESPAR (Electrically Steerable Parasitic Array Radiator) were implemented. The parasitic antenna array ESPAR, is a single-feed-port array antenna, composed both of one active element and multiple parasitic elements, terminated by switched lumped circuits or variable reactors. The parasitic array can drastically decrease the number of expensive radio-frequency (RF) chains integrated with active elements. It has been proven that the number of parasitic elements must be increased for realizing full 360 azimuthal beam and null forming. On the other hand, whether the number of antenna elements increases the complexity and the demand for power will be increased too. Therefore, parasitic array antennas with multiple feed ports have been proposed in order to decrease the number of antenna elements by keeping the beam and null forming capability. This type of antenna is called MuPAR (Multiport Parasitic Array Radiator). A MuPAR antenna consists of K-IFA antennas in which a single IFA antenna can be regarded as two infinitesimal radiators, which are vertical to the ground plane. The first radiator is the element denoted by “a”, which is connected to a feed circuit in case of the active element or of a parasitic element when connected to a variable reactor. The second radiator is the element denoted by “b”, which is the short pin of the IFA. The main purpose of our thesis was to develop a genetic algorithm that can provide optimized values for our parameters such as the amplitude and the phase of active elements and the loads of variable reactances in case of parasitic elements of a MuPAR antenna aiming in an optimized formulation of MuPAR antenna radiation pattern.