Feature: Communications system design
Table 1: Width of floating blocks
Figure 4: Surface current distribution in the filter at 4.88GHz Table 2: Length of floating blocks
constant. Tis ensures minimal signal degradation and enhanced filter performance, meeting the stringent requirements of high- frequency applications. Te design and optimisation of the square open-loop resonator
were performed with a 3D planar electromagnetic simulation soſtware called ‘Sonnet Suites’. Tis tool allowed for detailed analysis and fine-tuning of the resonator’s geometry; see Figures 1-2. Tese simulations provided valuable insights into the filter’s performance, enabling adjustments to achieve the desired specifications and optimise the overall design. Te final design’s simulation results reveal a -10dB return loss
bandwidth of 3.06GHz, ranging from 3.07GHz to 6.13GHz. Te minimum achieved input match is -32dB. Figure 3 shows the return loss (S11) and transmission
coefficient (S21) results for the resonator, providing a comprehensive view of the filter’s performance and effectiveness. Figure 4 shows the current distribution analysis of the
resonator at 4.88GHz. It can be seen that the current is concentrated around discontinuities and near the slots, which aligns with the expected behaviour of the resonator. Te figure includes a colour legend indicating the magnitude of the current in amperes per meter, providing a detailed view of how the current varies across the resonator.
Design steps and simulation results Aſter extensive simulation-based optimisations, the final dimensions of the filter were carefully selected to meet the design specifications. Te parametric studies shown in Table 1-7 provide the chosen widths and lengths, to ensure the filter’s performance is robust and resilient to potential fabrication variations. Table 1 shows the impact of varying the width of the floating
blocks on key performance metrics such as bandwidth and magnitude. Tis parametric analysis highlights how adjustments in width influence the filter’s behaviour, helping us achieve the desired performance whilst mitigating the risk of sensitivity to manufacturing deviations. Table 2 shows the variation in bandwidth and magnitude
26 December 2025/January 2026
www.electronicsworld.co.uk Table 4: Length of the four slots
Table 3: The gaps of the open loops
Table 5: Width of the four slots
Table 6: Lengths of the middle blocks between the loops
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