Manufacturing processes influence on millimeter-wave printed antennas and resonators characteristics

The rapid evolution of wireless communication technologies, particularly the rollout of 5G and emerging 6G systems, is driving the integration of devices operating in the millimeter-wave frequency range. This transition presents new challenges in the design and manufacturing of radio-frequency components such as printed antennas and substrate integrated waveguide (SIW) resonators. These devices, favored for their compact size, high performance, and ease of integration, are widely used in miniaturized mobile terminals and high-capacity base stations. However, due to their small geometries and tight design constraints, even minor production deviations can significantly alter their electromagnetic performance, affecting key figures of merit such as resonant frequency, quality factor, and coupling efficiency. This study investigates how common fabrication-induced geometric variations affect the resonant and transmission properties of SIW resonators and printed antennas produced using PCB technology. Optical measurements have been first conducted to determine actual manufacturing deviations in via placement, metallization thickness, and etching accuracy. Electromagnetic simulations have been then used to evaluate the sensitivity of key device parameters to these variations and to quantify their impact on electromagnetic behavior across relevant frequency range. For single-mode SIW resonators, the results have revealed that misalignment of metallized vias can cause resonant frequency shifts exceeding 5 GHz, indicating high sensitivity. In contrast, rounding of excitation slot corners had a much smaller impact, with frequency shifts limited to under 100 MHz. In multimode resonators, excitation slot misalignment up to 65 µm led to frequency deviations of over 200 MHz, while doubled copper cladding thickness did not have any significant effect. For printed antennas designed using a genetic algorithm, dimensional deviations of feeder lines and quarter-wave transformers reached up to 14%, but these deviations had minimal influence on the transmission coefficient between patches. However, variations in the size of metallic decoupling structures, or “pixels”, on the dielectric layers were far more consequential. Scaling pixel dimensions by ±20% resulted in changes of up to 13 dB in the transmission coefficient across the operating band. These findings highlight the design features most susceptible to manufacturing tolerances and provide actionable guidance for robust, repeatable mass production of millimeter-wave components.