The mesh is dynamically controlled by the Electromagnetic Waves, Frequency Domain interface based on each simulation frequency.ĭouble-ridged horn antenna excited by a coaxial port. The outermost layer of the air domain is configured to be a perfectly matched layer (PML), which simulates the absorption of all outgoing radiation from the antenna as would occur in a real anechoic chamber. This tutorial models a double-ridged horn antenna and computes the voltage standing wave ratio (VSWR), far-field radiation pattern, and antenna directivity.Ī lumped port is assigned on the boundary between the inner and outer conducting surface at the end of the coaxial connector. This is noticeably decayed in the vicinity of the absorbers.Īpplication Gallery link for the anechoic chamber tutorial model: RF_Module/EMI_EMC_Applications/anechoic_chamber New Tutorial Model: Double-Ridged Horn AntennaĪ double-ridged horn antenna is popularly used in anechoic chambers to characterize an antenna under test (AUT), from S-band to Ku-band, due to its reliable performance in a wideband frequency range. The contour plot shows the electric field distribution on the ZX-plane.
The computed far-field radiation pattern and S-parameter (S11) demonstrate that the microwave absorbers reduce reflection from the walls significantly without distorting antenna performance.Ī state-of-the-art anechoic chamber, built in a small room (3.9x3.9x3.3 m), consisting of microwave absorbers on thin conductive walls. This model simulates a biconical antenna, popularly used in EMI and EMC tests, which is located at the center of a small anechoic chamber.
By absorbing electromagnetic waves inside the chamber and blocking incoming signals from outside, the chamber creates a virtual infinite space that has almost no internal reflections and does not suffer from any unwanted external RF noises. Within the chamber are absorbers that are configured with an array of pyramidal objects that steer the propagating incident field onto their neighboring absorbers. The 0402 surface-mount device (SMD) inductors and capacitors are modeled using lumped element features on 2D boundaries.Īpplication Library path for the low-pass filter using lumped elements tutorial model: RF_Module/Filters/lumped_element_filter New Tutorial Model: Anechoic Chamber Absorbing Electromagnetic WavesĪn anechoic chamber is used to measure antenna characterization, electromagnetic interference (EMI), and electromagnetic compatibility (EMC). Both filter models present the S-parameters and electric field distribution. Then, a band-pass filter transformed from the low-pass filter design is simulated in the same frequency range. The geometry of each element (surface-mount device, SMD) is simplified as a 2D boundary and the electrical performance is modeled using the Lumped Element boundary condition in the Electromagnetic Waves, Frequency Domain interface. This example simulates two types of lumped element filters that are similar to lumped ports, except that they are strictly passive and there are predefined choices for inductances and capacitance.įirst, a five-element maximally flat low-pass filter is built to compute frequency responses that show the cutoff at the intended frequency. Passive devices can be designed using lumped element features if both the operating frequency of the device and the insertion loss of lumped elements are low. To do this, you include a Time Dependent study step using a lumped port in the Electromagnetic Waves, Transient interface, and then include a Time to Frequency FFT study step to perform the transform of the results from the first study step.Īpplication Library path for an example calculating S-parameters from transient simulations using a time-to-frequency FFT: RF_Module/Filters/coaxial_low_pass_filter_transient Updated Tutorial Model: A Low-Pass Filter Using Lumped Elements
Then, the S-parameters are calculated using a time-to-frequency fast Fourier transform (FFT) on the results.
Good for calculating wide-band frequency responses with a fine frequency resolution, models are first built using a transient physics interface. The electric field pattern (cone) resembles that of a short dipole antenna.Ĭalculate S-Parameters from Transient Simulationsįrequency-domain S-parameters of a circuit can now be calculated from time-dependent simulations by using a two-step solving process. Surface magnetic current density (blue arrows) on a cylindrical coil through use of the Surface Magnetic Current Density boundary condition in the Electromagnetic Waves, Frequency Domain interface.
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