## Electronics

Topics relate to HFSS, Maxwell, SIwave, Icepak, Electronics Enterprise and more

#### ansys siwave, near-end scan

• Kagan kr
Subscriber

I installed a simple pcb on ansys siwave. I defined the power lines. And I defined an ideal voltage source that gives only 18v on the pins. I set the near fields analysis as you can see.

interestingly, in near field scanning, I see magnetic fields occurring at 200mhz and 900mhz. How is this possible in a DC power supply? Is the simulation giving an erroneous result or is there something I missed?(note that I only added a dc voltage source, no current source or oscillating signal lines)

• Aymen
Ansys Employee

This is normal since you defined a frequency sweep in the Compute Near Field setup

• Kagan kr
Subscriber

yes, I am aware of this. as I understand it only scans the near field reflected from the system, it does not apply any frequency to the system.Near field “scanning” test helps us to see the magnitude and frequency of the magnetic field in the determined frequency range.It allows us to make a measurement from the close region, not exceeding the full wavelength of the wave emitted from the system. There would have to be an oscillating source for me to see such a result. But there is only one dc ideal source. What I expected was that I only saw a magnetic field at 0Hz, that is, in the non-oscillating region. How can a DC power source oscillate at different frequencies on pcb?

• Eka
Subscriber

This is a question I have been asking for a while now, someone from Ansys should please give us answers

• Eka
Subscriber

a direct current (DC) flowing in a conductor can generate a magnetic field. This is known as Ampere's law, which states that a magnetic field is produced around a conductor when an electric current passes through it.

When a DC current flows through a conductor, such as a wire, the moving charges (electrons) create a magnetic field around the conductor. The magnetic field generated by a straight conductor can be described by the right-hand rule, which states that if you point your right thumb in the direction of the current flow, the curling of your fingers around the conductor indicates the direction of the magnetic field lines.

The strength of the magnetic field produced by a DC current depends on factors such as the magnitude of the current and the distance from the conductor. The magnetic field follows a circular pattern around the conductor, with the field lines becoming weaker as you move farther away from the conductor.

It's worth noting that the magnetic field generated by a DC current in a conductor is typically considered to be static or constant because the current does not change with time. In contrast, an alternating current (AC) flowing through a conductor generates a time-varying magnetic field due to the changing direction and magnitude of the current.

My question is how does this frequency sweep works, are we sweeping the frequency of the power source from dc to a given frequency? but then we only specified dc voltage. We need answers please.