Abstract-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.Index Terms-Computer-aided design, multiplexing networks, resonator filters, wideband microwave components.

This paper presents a novel filter topology for the implementation of asymmetric responses with transmission zeros (TZs) in rectangular waveguide technology. It is based on a compact folded E-plane arrangement where adjacent resonators are capacitively coupled through rectangular slots, and nonadjacent resonators are coupled through simple inductive windows. The new folded configuration allows the introduction of transmission zeros above the passband, which can be easily controlled. High order filters can be designed by cascading an arbitrary number of resonators in a folded layout. Components based on this novel configuration are amenable to simple manufacturing processes and can be used in high-power environments. A triplexer containing filters implemented with the proposed topology has been designed. Measurements of a manufactured prototype are included to validate the use of this topology in practical applications.

Abstract-The design and physical implementation of hybrid folded rectangular waveguide (HFRW) filters providing multiple transmission zeros (TZs) below the passband are considered in this paper. These structures offer great flexibility to locate the TZs in a wide frequency range. Different implementations have been considered, each one offering certain advantages in terms of ease of manufacture, number of TZs and their separation from the passband. A simple design procedure for these structures is also described. Measurements of a manufactured 5-pole filter prototype, and simulations (obtained with several available commercial software tools) for different triplet sections, fully validate the novel configurations proposed in this work.

Abstract-This paper presents a capacitive obstacle for rectangular waveguide filters capable of realizing multiple transmission zeros (TZs). By combining a capacitive window with multiple thin stubs, a filter designer has the ability to control the total coupling implemented by the obstacle, and the frequency location of the TZs generated. The resulting structure is compact, and can be employed at the input/output and intermediate stages of direct-coupled-resonator filters. This letter includes a parametric analysis of the obstacle and practical design guidelines. To validate its practical application, an in-line five-pole filter realizing three TZs has been successfully realized.

This paper provides the guidelines for the practical development of novel advanced test beds for passive intermodulation (PIM) measurements. The proposed test beds are highperformance and flexible, allowing for the measurement of several PIM signals of different orders, with two or more input carriers. In contrast to classic test beds for satellite hardware, based on the cascaded connection of several elements, an integrated solution involving the minimum number of hardware pieces is proposed. The result is a lower number of flanged interconnections thus reducing residual PIM level and insertion losses. In addition, return loss degradation and harmful spurious generation in the interconnections are also avoided. Measurement test beds for conducted and radiated PIM, in both transmitted and reflected directions, are discussed, highlighting the benefits and drawbacks of each configuration. Design guidelines for the key components are fully discussed. Illustrative application examples are also reported. Finally, excellent experimental results obtained from low-PIM measurement setups, working from C band to Ka band, are shown, thus fully confirming the validity of the proposed configurations. Index Terms-Intermodulation distorsion, microwave filters, high-power filters, multiplexing, computer-aided engineering. I. INTRODUCTION I N the last decades, the avoidance of passive intermodulation effects (PIM) has become a top-priority issue for communication satellites systems engineers, as a consequence of the ever more demanding payload requirements [1], [2]. PIM may, in fact, become an important source of performance degradation due to increased transmitted power levels for higher capacity links, together with the need for simultaneous operation in transmission (downlink) and in reception (uplink) at different frequency bands [3], [4]. In the scenario of Manuscript