Miniature microstrip filter using high-permittivity ceramic substrates (er = 90)

This paper presents a C-band planar filter miniaturized through use of high-permittivity substrates to meet the specifications. The drawbacks associated to such substrates are briefly recalled. To overcome them, the filter under study was based on the DBR topology and realized on a high-K commercial substrate. This ceramic has a relative permittivity of 90 and a low dielectric tangent (tanδ <; 10-3). Finally, the results of simulations and measurements are presented and discussed, particularly the footprint reduction.