Resonant frequency in an series LC circuit

[mahesh n r]

How many resonant frequencies will we get in a series LC Circuit.

 

[karesz]

Hi,
I would say ; all resonant circuits have only one Fres.
I think the deepest frequency_ all other (effects) are products from some parasitics...
K.

 

[mahesh n r]

Thanks for the reply. I am about to solve an acoustic problem related wth helmholtz resonator. Usually helmholtz resonators have neck and a cavity. this neck can be replaced by inductor and cavity can be replaced by capacitor as an electrical analogy. When i solved the problem acoustically i got three reflections(ie resonat frequencies). But this electrical circuit gives only one frequency.
thank you

 

[karesz]

Hali Mahesh,
Your welcome!
Im not an audio specialist, but I would say, that than is your "equivalent" not enough proof...
I mean, your cavity`s measures(are all distances the same?) are not excellent for the frequency what you wish to resonate_eventually you can apply some trick & use dampings material on the critical walls!?
K.

 

[mahesh n r]

once again thanks. I have tried it on the basis of a paper published in Nature. Details are as follows.
Ultrasonicmetamaterials with negative modulus
NICHOLAS FANG, DONGJUAN XI, JIANYI XU, MURALIDHAR AMBATI, WERAYUT SRITURAVANICH,
CHENG SUN AND XIANG ZHANG*

From theory i am getting three stop-bands(resonant frequencies). .When I tried it in equvalent ckt, I got only one. this one perfectly agrees with the first stopband, that theory gives.
If u dont mind, tell me ur area of interest. my email id is mahesh.nr@hotmail.com

 

[FvM]

Acoustic resonators generally have modes, in so far a Helmholtz resonator has surely more than three resonant frequencies. An electrical equivalent circuit can be valid for the fundamental only (if at all). To model the wideband behaviour including all overtone resonances, LC ladders or transmission line models seem to be more promising, but they still won't be able to represent all possible geometries, only simple linear variants (e.g. thin tubes).

 

[karesz]

Oha!
You have forget to tell, that you plays with MetMat ..
I think in that case is some other thinking needed, then it must be an acting between meta mat and the signal frequency direct too_but as said, its not part of my profession!
I believe; you must more work on your (non)equivalent circuit_or modell...
K.

 

[bdsplexus]

I know little about meta-materials, but I have done some modeling of Helmholtz resonators using equivalent circuits. Previous posters are correct. A low-order LC equivalent circuit is only a valid model of a Helmholtz resonator at low frequencies, where the acoustic wavelength is much larger than the largest physical dimension of the resonator (though technically I believe you need 3 inductances and 2 capacitances to properly model the low-frequency behavior of a Helmholtz resonator - think about where kinetic and potential energy storage takes place in that type of system). Higher-order resonances will occur at frequencies above the range over which the low-frequency model is valid. To predict those it is possible to use more complex LC ladder or web structures, but it is substantially more difficult, if not impossible, to analytically derive the proper L's and C's from the resonator geometry and material properties. However if you just need to fit L and C values to yield a set of resonances you already know, that should be achievable much more easily. As another idea it might be possible to come up with an equivalent distributed electromagnetic structure that would yield a series of resonant modes similar to your acoustic resonator; you could simulate something like that using a 2D or 3D finite-element electromagnetic simulator. I've never tried that approach, but it might be interesting.