Design of In-Line Dual-Mode Rectangular Waveguide Bandpass Filters Using Multiple Inductive Circular Posts

Abstract

In this paper, the concept of utilizing circular inductive posts as a simple inductive discontinuity coupling method for the implementation of in-line dual-mode rectangular waveguide filter is introduced. The use of shunt inductive posts facilitates the fabrication process and reduces filter size/weight if compared to other dual-mode inductive coupling methods. The complete design procedure of the proposed structure is introduced. The proposed filter concept is validated by application examples which are fabricated and measured. Experimental results indicate excellent agreement with theory.

Inductive Cascaded Quadruplet With Diagonal Cross-Coupling in Rectangular Waveguide

“…However, for waveguide modes the guide-wavelength fractional bandwidth W λi should be used instead [1]. The formulas obtained in (11) are also valid for the cascaded and/or conjoined connections of any number (without limitation) of MQs.…”

“…Therefore, the same limitations apply: approximations worsen when the number of resonators increases, and when the relative bandwidth increases. However, for practical orders and moderate bandwidths, (11) and ( 12) work with outstanding precision. As reported in section II-B, it is very easy to obtain the reversal of the response given in Fig.…”

“…It is important to remark at this point that practical waveguide implementations of doublets based on dual-mode configurations without source-load couplings, were already reported in previous works, namely, [9] and [10], but without using an explicit term for the topologies. Furthermore, an additional contribution based on a rectangular waveguide dual-mode resonator as a basic doublet, where all couplings are implemented with inductive posts, can be found in [11].…”

Full-wave analysis of H-plane waveguide junction loaded with metallic posts

“…Convergence of the method is examined versus number of modes in structure and number of points considered as postfilaments in moment procedure. Finally, as an application example, the proposed method along with generalized scattering matrix (GSM) method is employed for analyzing dual mode waveguide filter mentioned in [5].…”

“…Waveguide sections including conducting posts are the key basic building block of many passive devices, such as adaptors, mode-launchers, power combining structures and filters [1][2][3][4][5]. Nowadays, with increase demands on planar and compact circuits, substrate integrated waveguide, also called laminated waveguide [6] or postwall waveguide [7] is very popular in designing microwave circuits.…”