|
As cellular mobile communication systems* markets are expanding
worldwide, miniaturization for portable telephones are strongly
required. Especially, the RF front end circuit components in the
portable tele-phones are required to be much smaller. For this,
miniaturization of microwave filters is one of the mean
concerns. The coaxial filters have been mainly used, but the
miniaturization becomes marginal. The multilayer planar filter,
made of ceramics which has high permittivity permits shrinkage
of the sizIn the experiment, the bandpass filter is designed
using coupled stripline theory and J-inverter theory. And the
designed structure is simulated using MDS (Microwave Design
System) and IE3D. The filter consists of parallel-coupled
striplines less than a quarter-wavelength and several coupling
capacitors, and its structure is made up of several layers of
Al2O3. A high performance, used for UHF band planar filter has
been designed and fabricated in the experiment.
|