Thermal analysis, design, and implementation of an L‐band high‐power stepped impedance low‐pass filter

Abstract

This paper presents high power, thermal analyses, and implementation of a stepped impedance high-power low-pass filter (LPF). A comprehensive model and analysis have been developed for the design and simulation of the LPF. In this analysis, power handling capacity and breakdown-voltage are discussed, and the effects of critical points are considered. The attenuation due to conductor and dielectric losses is also studied. The novelty of our approach lies in employing theoretical analysis to estimate the power-dissipation of the filter based on the proposed equivalent circuit. An accurate method is also introduced to calculate attenuation in the filter's elements. Thermal analysis to obtain accurate temperature profiles is done for the first time based on the electro-thermal simulation. Consequently, an effective cooling method is used to spread heat across the entire filter. Finally, the filter was implemented and tested to operate at L-band with handling 8 kW peak and 800 W average power. The insertion-loss is less than 0.27 dB, the stop-band attenuation is more than 60 dB, and the return-loss is better than 15.7 dB. The filter is capable of tolerating produced heat without any destructive effects at a maximum temperature of about 200 C above ambient. The theoretical analysis and experimental results show that the LPF is suitable for high-power microwave applications.

Multicore–Shell Direct Ink Writing of Coaxial Transmission Lines

“…A ninth-order Chebyshev-type low-pass filter consists of four units based on such a structure is constructed for simulation, and the outer conductor is assumed to be the fabricated Ag conductor. The corresponding results are shown in Figure f, and samples 1 and sample 2 display typical characteristic curves of a stepped impedance coaxial LPF with different cutoff frequencies of ∼35 and ∼28 GHz due to the difference in high impedance branch’s diameter, respectively, ,, Before the cutoff frequency, higher diameter in high impedance branch (neck) generates lower impedance and lower loss, and thus, sample 1 exhibits smaller return loss (S11) and higher transmission efficiency (S21) compared to that of sample 2. These demonstrations depict the promising potential of this novel strategy in constructing RF electronics, which will bring great innovation in improving fabrication efficiency and diversity.…”

“…For example, RF coaxial transmission lines and filters require high-purity and highconductivity metal materials, as well as the ability to customize core conductor patterns. 29,30 Unfortunately, the metal-based conductive materials reported previously are the most common composites such as Ag/TPU (thermoplastic polyurethane), decreasing the conductivity compared to that of pure metal. Although some reports introduce liquid metal into the multicore−shell DIW, 31,32 tion with other devices.…”

“…Although this technique has come a long way, it is necessary to extend applied realms to some virgin fields such as radio frequency (RF) transmission lines, which play an important role in AC signal transmission. For example, RF coaxial transmission lines and filters require high-purity and high-conductivity metal materials, as well as the ability to customize core conductor patterns. , Unfortunately, the metal-based conductive materials reported previously are the most common composites such as Ag/TPU (thermoplastic polyurethane), decreasing the conductivity compared to that of pure metal. Although some reports introduce liquid metal into the multicore–shell DIW, , the low viscosity and high surface tension of liquid metal usually leads to droplets, restricting the controllability of core patterns and impeding the interconnection with other devices.…”