Which frequency & single or large Magnetrons

What frequency should I use?

Single or multiple magnetrons?

Both of the above questions are sometimes related. Some facts about each approach are listed below:

  • Magnetron efficiencies are between 50-72% for 2.45GHz compared to 80 to 87 % for high power 922 or 915MHz.
  • The lower the frequency the great the penetration depth into a material.
  • Field uniformity is usually better when multiple magnetrons are used.
  • There are no 915 or 922MHz magnetrons less than 5kW.
  • At 2.45GHz magnetron range in power from 1kW to 30kW, at 915MHz the range is from 5kW to 100kW.
  • Different frequencies can initiate different energy transfer mechanisms within the material being heated, which may impact on reaction thermodynamics or product quality.
  • Applicator dimensions and complexity would be much greater using multiple magnetrons.
  • The larger the applicator greater will be the thermal losses and reduced microwave efficiencies. A larger applicator would be required if multiple magnetrons were used.
  • In multiple magnetron installations, magnetron life is reduced due to cross coupling of power between each.
  • Multiple magnetron systems provide a high degree of redundancy.
  • Multiple low power magnetron generators are simple in design allowing any technician microwave technician to repair them.
  • In some situations the replacement cost of low power magnetrons per kW can be higher than that of high power magnetrons.