Far‑field radiation from magnetoelectric antenna driven by piezoelectric–piezomagnetic coupling (no electrical port)

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Hello everyone, I am working on a magnetoelectric (ME) antenna model in COMSOL Multiphysics and I would appreciate guidance on the correct strategy to compute the far‑field radiation. Model description The antenna is composed of: grounded Mo bottom electrode, piezoelectric AlN layer, magnetostrictive FeGaB layer The surrounding medium is a spherical air domain (inner sphere, and outer pml sphere) The physics interfaces used in the near‑field study are:Electrostatics (ES), Solid Mechanics (SM), Magnetic Fields (MF) with the following multiphysics couplings:Piezoelectricity (ES ↔ SM), Piezomagnetism / magnetostriction (SM ↔ MF) The system is solved in the frequency domain. A harmonic voltage is applied across the piezoelectric layer, generating strain that propagates into the magnetostrictive layer and produces a time‑varying magnetization. An external bias magnetic field is also applied in the air domain. Importantly, this antenna is not electrically fed (no lumped port, wave port, or impressed current), as the source of radiation here is the antenna due to the magentization evolution in FeGaB. My Question: I would like to compute the far‑field radiation pattern of this antenna. I added the Electromagnetic Waves, Frequency Domain (EMW) interface and tried to use COMSOL’s near‑to‑far‑field transformation, but all far‑field quantities (e.g. emw.normEfar) evaluate to zero. I understand that: 1. Far‑field calculations in EMW require a non‑zero electromagnetic near field (E, H) 2. EMW does not directly couple to Magnetic Fields, Solid Mechanics, or Electrostatics 3. Variables such as mf.Mx, mf.Hx, or es.V are not accessible inside EMW as sources I attempted to introduce equivalent magnetic or electric current sources based on the magnetization, but EMW does not recognize variables from the MF interface, even when defined through component variables.

Questions 1. What is the recommended COMSOL workflow to compute far‑field radiation from a mechanically driven magnetoelectric antenna that has no electrical port? 2. Is the correct approach to: Perform a first study to compute the magnetization, then use a second EMW‑only study with an equivalent current (calculate it in matlab based on the output magnetization or field that i wil get due to the near field study)? 3. Are there any built‑in features or best practices in COMSOL for handling radiation from magnetization‑driven sources (e.g., magnetic dipole–type antennas)?

Any guidance, references, or example models would be greatly appreciated. Best regards, Rayan


2 Replies Last Post 7 gen 2026, 05:12 GMT-5
Konstantinos Tsoukalas

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Posted: 1 day ago 6 gen 2026, 11:12 GMT-5

I think that COMSOL doesn't have a direct MF→EMW radiation coupling because the MF interface uses quasi-static assumptions (displacement current neglected), while EMW needs the full Maxwell equations. These are fundamentally different approximation regimes. I suggest that you do your near field study and then export the data from Comsol and take the far field transformation by yourself. There are various Near-Field to Far-Field Transformation packages in Matlab file exchange for example.

I think that COMSOL doesn't have a direct MF→EMW radiation coupling because the MF interface uses quasi-static assumptions (displacement current neglected), while EMW needs the full Maxwell equations. These are fundamentally different approximation regimes. I suggest that you do your near field study and then export the data from Comsol and take the far field transformation by yourself. There are various Near-Field to Far-Field Transformation packages in Matlab file exchange for example.

Edgar J. Kaiser Certified Consultant

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Posted: 12 hours ago 7 gen 2026, 05:12 GMT-5

I am wondering if it wouldn't be possible to apply the electric field components from the mf-node (mf.Ex, mf.Ey, mf.Ez) to the far field boundary in an emw-node?

Just a wild guess, I haven't been doing it myself.

Cheers Edgar

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Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
I am wondering if it wouldn't be possible to apply the electric field components from the mf-node (mf.Ex, mf.Ey, mf.Ez) to the far field boundary in an emw-node? Just a wild guess, I haven't been doing it myself. Cheers Edgar

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