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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

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In this paper we propose a novel Ka-band waveguide diplexer for passive intermodulation (PIM) measurements. Due to the higher operating frequency, this type of measurement setup usually requires wide band filters. In addition, due to the very large separation between satellite uplink and downlink bands, the PIM measurement diplexer unit must operate over a very wide frequency band. To satisfy such wide bandwidth requirements, the proposed topology is based on a band-reject filter for the downlink frequency band which is designed to provide, at the same time, the optimal passband performance for the downlink, and the optimal equiripple rejection over the PIM band. For the PIM channel, a band-pass filter combined with a high-pass section has been used. To validate the design, a prototype has been designed and manufactured. Very good agreement is shown between simulations and measurements, thereby fully validating the proposed solution.

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