RF-MEMS Closed-Bridge Analysis

Example description

In this example RF-MEMS (Micro Electro-Mechanical Switch), realized on a coplanar waveguide is simulated. It is produced on very thin substrate layer. The working mode of the RF-MEMS may be described by two states: Closed (Bridge is down) and Open (Bridge is up), see Fig. 1. In this example the Closed bridge mode is considered. Since the structure is symmetric, a magnetic wall is introduced in order to reduce the computational effort. The Closed state of the switch is simulating introducing a dielectric material with high permittivity placed under the bridge. This can be done, because the bridge does not go down completely, i.e. the switch is capacitive in Closed working mode. The complete simulation, required to calculate the correct S parameters, is very lengthy, therefore the provided version has only 10000 timesteps. This length is enough for good visualization of the fields.

Fig. 1: The RF-MEMS model.

TLM model

The RF-MEMS structure, excitation-type and simulation setup are given in the TLM model files I3D.Closed.

The structure is excited with a Gaussian signal. The excitation is modeled by Templete (see documentation) which excites the field distribution of the fundamental mode. Absorbing boundary conditions are used at the boundaries of the simulation domain.

Fig. 2: The model of the simulated structure.

Simulation Results

Fig. 3: Time domain voltages signals measured at several different ports.

Fig. 4: The |S21|.dB.

Fig. 5: A snapshot of the field distribution over the RF-MEMS.