The Study On Patch Antenna With Electromagnetic Bandgap Structure By Low Temperature Co-fired Ceramics Technology

The concept of photonic crystal was proposed in1987, since then it hasbeen attracting many scientists to research in this field and a variety ofachievements have been demonstrated or envisioned. The fabricationmethodology changed from drilling holes in certain substrate and stackingdielectric rods to etching method in order to reduce the dimension of the PCstructure which made it possible to apply the PC structure into more and morefields. Existence of a bandgap in certain frequency is the major feature of thephotonic crystal structure; therefore it can serve in fields of communication,navigation and radar. We can say that this structure can be used in any fieldthat concerns about the propagation of electromagnetic wave. As an importantsubassembly of the modern communication system, antenna has changed fromserving as a simplex transfer of the electromagnetic wave to a signal analysissystem; form implementing the electric capability by mechanism tomechatronics system; from mechanical workout to screen printing andintegration technology. With the development of micro-electronics large scaleintegrated circuit technology, antenna has become the bulkiness ponderositypart of the electronic equipment, so the miniaturization became urgent. Butthere was a difficult problem along with the miniaturization: the reduction ofthe antenna’s radiant efficiency. In order to solve this problem, we introducedthe photonic crystal structure into the substrate of the antenna. We hope thatthe bandgap of the photonic structure can play the role of enhancing theradiant efficiency. We designed the photonic crystal structure according to thesimulation result of HFSS, and it turned out the measurement result wasaccord with the simulation. The designed structure was fabricated by a methodof tape casting, screen printing and low temperature co-fired ceramicstechnology（LTCC）. Its combines the technology of multi-layers ceramics andmulti-layers circuit diagram. Low temperature co-fired ceramics andconductor material with high conductance melting point are co-fired below 900℃which form a three dimensions ceramics multi-layers circuitmodularization consists of inner connection and passive elements. Our designin this paper was a multi-layer ceramics structure with metal circuit diagramin it, and we realized the plan in product line which united the lab theory andthe practically production. We realized the photonic crystal structure with theLTCC technology which was an innovation attempt. The photonic crystalstructure was employed into the substrate of the patch antenna to reduceexcitation of surface waves by a patch antenna, and this can result in goodimprovement of antenna performance including the efficiency, the gain andthe reduction of the back radiation.