Modelling and testing microwave magnetrons.
Loading...
Date
1988
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Though declining in popularity over the last decade, the magnetron
still has applications where portable high power is needed. This study
examines the predicted performance of cylindrical microwave magnetrons
using analytic lumped-spoke models based on the energy conservation
principle. The analytic approach is still favoured when small computer
systems are used and the overall performance of the tube is to be
predicted. The magnetron elements are examined and the role they play
in the overall device performance analysed. Simplified representations
of these elements are used to construct a complete magnetron model.
The Hartree threshold condition is reexamined and a new, more accurate
analytic formulation proposed. This formulation is based on electric
field strengths at the base of the magnetron spoke. The effect of the
space charge on the threshold condition is included. Spoke current has
been evaluated at the edge of the Brillouin hub. The resulting anode- cathode
voltage performance predictions are consistent with measured
results. A computer program has been written to analyse the
performance predicted by this model. Models proposed by other authors
are examined, and compared to this model. The resulting model has been
tested by comparing predicted results to the measured performance of
four slot-and-hole magnetrons.
To facilitate accurate magnetron testing, a new automated triple-stub
high power microwave load has been developed. The load operates at a
peak power of IMW from 2,7-3,OGHZ, and allows the change of the VSWR
to any value along any path within the VSWR=I, 5: I circle. The
development of the triple tuner and termination is discussed in
detail. A new waterload configuration which has the advantage of
simple construction yet good matching characteristics is presented.
Automated measurement of pulling figure and construction of Rieke
diagrams is discussed. The accuracy of the complete load is compared
to conventional loads currently in service in the tube industry.
Description
Thesis (Ph.D.)-University of Natal, Durban, 1988.
Keywords
Magnetrons--Mathematical models., Magnetrons--Testing., Microwave devices., Theses--Electronic engineering.