In this study, a dual‐broadband reflective polarisation converter with high efficiency for both linear‐to‐linear and linear‐to‐circular polarisations based on a metasurface is proposed. Owing to the characteristics of strong anisotropy and multi‐order plasmon resonances, the proposed polarisation converter can rotate an y/x polarised electromagnetic wave to its cross‐polarised (x/y) direction in the lower frequency band of 7.74–14.44 GHz (a fractional bandwidth of 60.4%) with over 0.9 polarisation conversion ratio. Besides, the proposed structure can also convert a linearly polarised incident wave to a circularly polarised one after reflection in the higher frequency band of 14.95–17.35 GHz (a fractional bandwidth of 14.9%). The performance in the two bands can be controlled separately by altering the proper parameters of the structure. Numerical analysis is used to predict the polarisation states of the proposed polarisation converter. Moreover, the physical mechanism of multiple resonances is discussed based on surface current distributions. A prototype of the polarisation converter is fabricated and measured. A reasonable agreement between the experiments and simulations is obtained. The design has a simple and scalable geometry, and is a good candidate for polarisation control devices in microwave, terahertz and optical frequency regions.

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Analysis of the coexistence of two or more types of equipment is increasingly important. However, at present studies on the analysis method in the time domain are scant. Therefore, the aim of this paper is to explore the characteristics of signals and relations between interfering and desired signals in the time domain. Based on the periodicity of a signal, this paper presents a Periodic Pulse Overlap Method (PPOM). Using PPOM to analyze the interference from Distance Measuring Equipment (DME) to Air Traffic Control Radar Beacon System (ATCRBS) in the time domain, we obtain almost the same result as that based on the Monte Carlo Method (MCM). Furthermore, we discover the measures to reduce or even avoid interference, such as changing the Pulse Recurrence Frequency (PRF), adjusting the difference of initial time, and switching the operating modes of the equipment.