Manifold-coupled Multiplexers Research Articles

Applied Cavity Perturbation Used for Frequency Identification of Channel Ports in Manifold-Coupled Multiplexers

We investigate a practical technique for deembedding the channel filter S-parameters of manifold-coupled multiplexers (MUXs), without detaching filters from the manifold. The method is applicable for MUXs with an arbitrary number of channels and can be used for the device regardless of its bandwidth, guard band, or loss of filters. We reconfigure the N-port MUX to two simpler networks cascaded to each other. We assume that the manifold response is unknown and use the idea of applied perturbation on the channel filter, and then by comparing the response of the overall cascaded network, before and after the perturbation, we approximate the channel port response. The technique is useful in fast detecting the unexpectedly detuned channels or likely faults in the device without unnecessary plugging/unplugging; it is also useful in roughly tuning of the channel filers at the early stage of MUX tuning. The technique can be easily traced by the telecommunication community.

A practical de‐embedding technique based on the network theory for the filters in a 2‐channel multiplexer

A novel approach to de-embed the frequency response of filters connected to a 2-channel multiplexer without the need for unplugging is proposed. The technique to manifold coupled multiplexers with arbitrary number of filters is also theoretically generalised. In multiplexer tuning, there are practically important circumstances in which it is advantageous to de-embed the frequency response of filters in multiplexers without detaching them. The authors show that using a novel technique and reasonable approximations, all filters of a multiplexer can be modelled by simple microwave networks, and then, the equivalent rational function of the channel filters can be estimated appropriately by the rational H 2 approximation; extraction of this model facilitates tuning of the filters using the coupling matrix method. The impact of mechanical tolerances on the accuracy of the proposed technique is also studied. Next, this method is examined on a 2-channel multiplexer and its application in de-embedding and tuning of its connected filters is verified. Provided that the mechanical tolerances of the structure are sufficiently small, this technique is a powerful engineering solution towards tuning of manifold-coupled multiplexers.

Design of Compact Wideband Manifold-Coupled Multiplexers

The design of manifold-coupled multiplexers for wideband applications is considered in this paper. A systematic procedure, based on the sequential connection of filters to the manifold and subsequent adjustment of the interconnection elements, is presented. The filters are attached to the manifold without using stubs in order to minimize the effect of spurious resonances. The interconnection elements, the manifold, and the remaining filters are considered as the first inverter of each new filter that is attached. This technique has been applied to several practical examples. The obtained results validate the proposed design methodology.

Efficient Design of Waveguide Manifold Multiplexers Based on Low-Order EM Distributed Models

In this paper, a new systematic technique to design manifold-coupled multiplexers in waveguide technology is proposed. The new technique uses generalized low-order electromagnetic (EM) distributed models, which constitute a half-way point between the fast, but imprecise, analytical models, and the more accurate, but costly, full-wave EM models. The method can be applied to contiguous and noncontiguous channel multiplexers, in both $ { E}$ -plane or $ { H}$ -plane configurations. This paper covers the complete design procedure for manifold multiplexers, starting from the required specifications and finishing with the physical dimensions. After explaining the general design technique for multiplexers with channel filters based on transmission-line resonators, the method is specialized for the design of classic multiplexers with circular-waveguide dual-mode filters. As a further application example, the same methodology is also used for the design of a nonconventional tuningless wideband multiplexer with a new type of rectangular waveguide filters. This paper is concluded with a comparison between simulation and measurements for the wideband multiplexer. Excellent agreement between measurements and simulations are demonstrated, thereby validating the complete design procedure.

Synthesis of Star-Junction Multiplexers

Modern microwave communication systems generally employ filtering subsystems composed of narrowband filters suitably interconnected, whose purpose is the separation (or combination) of several RF signals allocated in different segments of the frequency spectrum (channels). Such subsystems are generally referred to as “Multiplexers.” Actually, several classes of multiplexers exist, which may differ, even noticeably, in overall topology. These classes can be grouped in two very general families: manifold-coupled multiplexers and star-junction multiplexers. In a past issue of IEEE Microwave Magazine, an overview of the design techniques for the former family was given, so this article will focus on the star-junction multiplexers.

Design of manifold-coupled multiplexers

Following a brief review of different types of multiplexer configurations, a systematic design approach has been outlined for the design of manifold-coupled multiplexers. The piecewise approach, optimizing parts of the multiplexer separately in repeated cycles while converging upon an optimal solution, has proved to be very effective for most practical applications. The technique is readily applicable to manifold multiplexers incorporating an arbitrary number of channels, regardless of their bandwidths and channel separations. There are no restrictions on the design and implementation of channel filters onto the manifold; they may be asymmetric, and may incorporate transmission zeros, group delay equalization zeros, or both. The manifold itself is a transmission line, be it a coaxial line or a rectangular waveguide or some other low-loss structure. The costly EM simulation is used economically on manifold junctions and channel filters through the use of space-mapping optimization techniques, where EM-based simulators are used to fine-model each multiplexer channel and coupling matrix representation is used to coarse-model the performance. Fine details such as tuning screws may be included in the design process. This design procedure takes into account the effects of dispersion and spurious modes and, as a result, the overall design and final tuning time can be significantly reduced.