High-Q dielectric combline resonator with wide spurious free performance

Lower dielectric constant material loaded Combline resonators achieve high-Q and excellent spurious free performance is presented. A design and characteristics are discussed. Simulated responses are presented in this paper

Coupling coefficients of combline resonators

Bandpass filters require elements that behave as series or parallel resonant circuits. In this paper, we discuss a variety of couplings between combline resonators in bandpass filter applications. Coupling coefficient used in filter realizations has been precisely calculated. Filter responses are presented by simulation, experiment and calculation. They were in very good agreement

Coloumb interaction and instability of CE-structure in half doped manganites

In their Letter (Phys. Rev. Lett. 83, 5118 (1999)), den Brink, Khaliullin, and Khomskii proposed theoretically that the one-dimensional ferromagnetic zigzag chains in CE phase in half-doped manganites play an essential role in forming the orbital ordering, and, more surprisingly, the on-site Coulomb interaction U between electrons with different orbitals leads to experimentally observed charge ordering. In this Comment, I point out that the strong U will destroy the stability of CE-type phase, which is stable in a very narrow regime in the parameter space for electronic model.To solve this issue finally, we have to take into account other interactions, such as the long-range Coulomb interaction, Jahn-Teller distortion, and physics of topological berry phase. For example, the effect of finite large J$_{H}$ leads to an attractive particle-hole interaction, which favors to stabilize the charge ordering.Comment: 1 page, 1 figure, To appear in Phys. Rev. Let