Advanced Compact Setups for Passive Intermodulation Measurements of Satellite Hardware

Abstract

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

Waveguide Quadruplet Diplexer for Multi-Beam Satellite Applications

“…The diplexer can therefore be safely considered to be multipactor-free. Additionally, the diplexer has low insertion losses and has been designed following the low PIM design guidelines discussed in [28].…”

Analysis of passive intermodulation between rough rectangular waveguide flanges using fractal method

“…In order to validate the analysis for PIM level of rectangular waveguide, the third order PIM level of rectangular waveguide is measured with PIM measurement system . And the PIM measurement system is shown in Figure .…”

Implementation of Waveguide Terminations With Low-Passive Intermodulation for Conducted Test Beds in Backward Configuration

“…On the other hand, a high pass filter will be issued for those test benches where the PIM band is below the transmission carriers (although a combination of a band-pass filter and a high-pass filter is also possible, as shown in section III.B. of [4], if a more compact solution is sought to reduce mechanical stress). In both cases, the filter must have outstanding PIM performance.…”

“…Tuning elements must therefore not be used. The filter must also be manufactured in clam-shell configuration with symmetrical width, to avoid cutting currents in the assembly [4].…”

“…In addition, they are also suitable for measuring PIM of oneport devices. However, as it has been pointed out in [4], the PIM performance of the dummy termination at the end of the common RF path is critical for backward PIM test beds. The high-power carriers reach the load, so it can generate relevant levels of passive intermodulation.…”