APPLICATION NOTE

THERMAL ANALYSIS OF 100 GHZ WAVEGUIDE BAND-PASS FILTER

Rectangular waveguide structures for bandpass filters with inductive irises are the most suitable and popular solutions for the THz (Terahertz) region. They are indispensable components of microwave links for satellite and radio communication systems to reduce the occurring interference signal and to filter the desired frequencies.

In this study, a 100 GHz rectangular waveguide band-pass filter with two transmission zeros symmetrically located at both ends of the structure, is presented. The four-pole filter is composed of two dual-mode resonators with unequal width, two WR-10 standard waveguide interfaces with rounded corners for inductive irises in series. Thermal behavior of the BPF is investigated.

The next figure shows the schematic illustration, cross-section view and 3D design of the studied BPF with its outer metallic cover.

Figure 1 - a)- The schematic illustration [1] b)- cross-section view and c)-3D design inside SOLIDWORKS of the studied BPF

The S-parameters solver of HFWorks is used (excitation power 1W), coupled to the thermal for a working frequency range of [94 GHz-106 GHz].

The electric and magnetic field distributions are presented in Figure 2.

Figure 2 - a) Electric and b) Magnetic field distribution at 100GHz

The return and insertion losses plot versus frequency is presented in Figure 3. Simulation and measurement results agree very well.

The deviation of insertion and return loss results could be caused by uneven surface error or unclose connection between the filter structure and the network measurement analyzer [1].

Figure 3 - Return and insertion loss results versus frequency compared to measurements.

A steady state thermal analysis coupled to the S-parameters study is used to perform the thermal behavior of the studied BPF.

Temperature distribution across the filter air cavity with an average of 35.87 C is shown in Figure 4). Heat flux density is plotted in Figure 5). It demonstrates maximum value at the rounded corners of the inductive irises.

Figure 4 -Temperature distribution at 100 GHz

Figure 5 - Heat flux distribution at 100 GHz