Compact Coaxial Filters for BTS Applications
A new class of coaxial cavity filters with low-profile suitable for base transceiver station applications is proposed. The benefits of the technology are volume reduction, high performance, and superior spurious-free response. An equivalent lumped element circuit allows for a fast and efficient initial design of the resonators. Full-wave optimization is required to produce the final configuration of the filters. Experimental results demonstrate the high performance of the proposed filters. The electrical length of the experimental resonators is as low as  $\lambda _{0}/16$ . The measured insertion loss of the five-pole filter is 0.92 dB at 722 MHz. Experimental results show a spurious-free response of the order of 7.6 times.
A full wave analysis of a conductor post insert reentrant coaxial resonator in rectangular waveguide combline filters
Due to its wide tunability region in performance and compactness in size, conductor post insert reentrant coaxial resonators are widely used in combline filters for mobile communications. This paper, for the first time, presents a full wave electromagnetic model for the reentrant coaxial resonator in rectangular waveguide combline filters. The model is based on the orthogonal expansion method and provides a formally exact modal solution to the problem. The model has been extensively verified by experiments and can be used in calculating resonant frequency, coupling values, or in constructing a key building block in full electromagnetic design of waveguide combline filters.
Laminar heat or mass transfer in rectangular channels and in cylindrical tubes for fully developed flow: comparison of solutions obtained for various boundary conditions
Abstract A comparison is made of results obtained with various boundary conditions at the wall of the channels. By comparing blood Sherwood numbers for finite wall resistance with those for constant concentration boundary condition only a small variation is found for various points along the blood channel.