Design of microstrip patch antennas in LTCC technology

Abstract

LTCC (Low Temperature Co-fired Ceramic) is a process technology used to manufacture circuits with multiple layers. LTCC has been mainly used for integrated circuits. However, its applications to microstip patch antennas are also advantageous. Microstrip patch antennas have been designed and manufactured with different materials for many years within the Antenna Group of the German Aerospace Center. However, the group had till present no experience with LTCC technology. The aim of this work is to determine the advantages and disadvantages in the modelling and fabrication of microstrip antennas in LTCC technology taking into account the manufacturing constraints. For this purpose a design of a single patch antenna for future use in an array is done. LTCC technology can handle buried active and passive components, and the manufacturing is suitable for mass production at low cost. A drawback of LTCC is that it uses substrates with high dielectric constant causing inefficient radiators. Techniques for improvement of the efficiency, radiation pattern and polarization bandwidth of patch antennas are also analysed. With the aid of simulation tools, it is shown that the gain pattern of patch antennas can remain constant through a wide observation angle with respect to broadside. This is a useful result when extending the single element design to an array.