Design of Periodic Structures for Antenna Applications

It has been shown recently, that wireless communication systems can achieve increased performance and reliability by utilizing multiple antennas both at transmitter and receiver sides. These systems, which are called multi-input multi-output (MIMO) antennas can provide an increased capacity without changing the operational bandwidth.

The main problem of MIMO systems is that if two or more MIMO antennas are located close to each other there will be mutual coupling between them. Because of mutual coupling, there will be degradation of the radiation pattern and the input impedance will change, which decreases the radiated power. One way to reduce the mutual coupling is to isolate the antennas with electromagnetic bandgap structures.

Two rectangular patched antenna are designed on the same substrate, and the crosstalk between them in function of their separation distance is investigated. Simulations with full wave electromagnetic solvers reveal that the coupling can be partially attributed to surface waves emitted by one of the antennas and received by the other antenna. The surface waves can be reduced with bandgap structures, which are placed between the patch antennas. Mushroom type electromagnetic band gap structures are designed and their geometry is optimized in order to find the minimum sized unit cell at the working frequency of the antennas. The details of the design procedure are presented. Equivalent circuit models are constructed to facilitate the selection of the geometrical dimensions for the electromagnetic solver. The band diagrams of the mushroom type electromagnetic band gap structure are calculated.

szerző

coskun aysu
Villamosmérnöki szak, mesterképzés
mesterképzés (MA/MSc)

konzulens

Dr. Szabó Zsolt
Docens, Szélessávú Hírközlés és Villamosságtan Tanszék