Research On New Multi-mode Cavity Devices

Microwave cavity passive components are widely used in the base-station and radar communication systems.Filters and diplexers are the most common RF front-end devices,which are applied to tansmit the expected signals and block the unexpected noises.Besides,other kinds of passive components are proposed in this dissertation.Three fundamental modes in a single cavity,namely TE₀₁₁,TE₁₀₁,and TM₁₁₀ modes,are utilized for the circuit design due to their two crucial characteristics:the modal orthogonality among these fundamental modes and easy to achieve reversed phase imbalance in each mode.In this paper,many passive devices are presented using the characteristics of these modes,and they all achieve high performance,which dramatically devotes to the development of the cavity passive components:???A novel approach for design of a miniaturized cavity triplexer is proposed by using triple-mode resonator?TMR?as a common feeder of three frequency channels in a triplexer.Three frequency channels are generated by three fundamental modes of a single rectangular triple-mode cavity resonator.Without installing any connection-oriented junction network,i.e.,T-or star-junction,only coupling slots are adopted herein to achieve required coupling coefficients and external quality factors towards the specified Chebyshev responses in the three passbands simultaneously.High isolation among these three separated bands can be effectively achieved owing to the modal orthogonality via sharing a common triple-mode resonator structure as a feeder.???A novel concept and approach for integration of a three-state diplexer?TSD?by utilizing the triple-mode cavity resonators is proposed.The proposed three-state diplexer has the inherent nature of three frequency channels,two of which can be utilized for duplexing channels by exciting one port as the input in each state.Meanwhile,three fundamental modes,namely,TE₀₁₁,TE₁₀₁,and TM₁₁₀,are excited in the triple-mode resonators?TMRs?to control these three frequency channels.???The design of cavity crossover with three intersecting channels is presented.Two kinds of crossover,for narrow-band and broad-band applications,are presented.For narrow-band case,the proposed crossover resonates at 2.91 GHz with the fractional bandwidth of 1.4%.For broad-band case,the proposed crossover resonates at 3 GHz with the fractional bandwidth of 24%.???A series of designs for cavity balanced and unbalanced filter/diplexer,are proposed and summarized for the first time.The balanced and unbalanced designs can be categorized into four groups:unbalanced-to-unbalanced?U2U?,unbalanced-to-balanced?U2B?,balanced-to-unbalanced?B2U?,and balanced-to-balanced?B2B?.Firstly,four types of cavity balanced and unbalanced filters are designed.Secondly,these four types of filters are entirely converted into diplexers.Therefore,four types of diplexers are designed with balanced/unbalanced input and outputs for different applications.