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  1. probewizzard

    MRI -please help !

    Hi all, just to clarify some "details": 1.) NMR means "nuclear magnetic resonance" because this technique excites and detects changes in the spin states of the NUCLEI (and not the electrons). However its possible to excite the electron spin-states too, but this is done in the so called ESR...
  2. probewizzard

    LOOKING FOR DIELECTRIC RESONATOR FROM 400 TO 900 MHz, PLEASE!!

    Hi, since I have been cited (thanks for the honour;-) I want to contribute to the discussion... 1.) If your project is still hot, check a small french company TEMEX. The people there are quite kind and they will listen to your questions and may give you some hints (as opposed to murata... but...
  3. probewizzard

    Dielectric Resonator - anybody knows material with eps_r > 400 and...

    Hi Higgler, sorry for answering that late.... (couple of months now;-) To answer the first question, no I am no part of bruker, although we are working with their spectrometers. NMR spectroscopy is a method to investigate a given sample with respect to the chemical properties (chemical bound...
  4. probewizzard

    Dielectric Resonator - anybody knows material with eps_r > 400 and...

    Higgler: The resonator is used not for imaging in bodies, instead for high field solids NMR. Penetration depth, at least due to parasitic e-field components, is the problem: Compared with a classical solenoid coil a DR in TE01d-mode has a reduced electrical field inside the sample volume and...
  5. probewizzard

    Dielectric Resonator - anybody knows material with eps_r > 400 and...

    biff44: Indeen, I do care since I use high power pulses up to 1kW to excite the resonance. That means that the resonator gets warm and if you observe the reflection during (!) the pulse (pulselength ~ 10ms and duty cycle 1s), the resonators frequency will drift away. I got a prototype of a...
  6. probewizzard

    Dielectric Resonator - anybody knows material with eps_r > 400 and...

    biff44: yes, you are right, there are materials used for capacitors, but unfortunately they have a far too high temperature dependence in eps_r (not so much in expansion). So the quest is for a material with high eps_r and a temperature compensation/stability which is unmagnetic. Any more...
  7. probewizzard

    Dielectric Resonator - anybody knows material with eps_r > 400 and...

    Hi all, I am a r&d engineer in a company for analytical devices in magnetic resonance equipment. For one of our recent projects we have to design a dielectric resonator with a very low resonant frequency (700MHz ... 1GHz). This is not a big problem as long as you have the right dielectric, and...
  8. probewizzard

    material with eps_r > 400 and tan_delta ~ 0.005

    Hi all, I am a r&d engineer in a company for analytical devices in magnetic resonance equipment. For one of our recent projects we have to design a dielectric resonator with a very low resonant frequency (700MHz ... 1GHz). This is not a big problem as long as you have the right dielectric, and...
  9. probewizzard

    Design of helical resonator

    Hi Geami, I think that there is some kind of missunderstanding: 1.) your "coil" is no coil anymore since as you said, it is a lambda-half resonator, therefore you can`t estimate the inductance with the simple formula above. 2.) dimensioning a helical resonator (or to be more precise a coaxial...

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