Second harmonic suppression in helix traveling-wave tubes
A filter structure to suppress the second harmonic component in the RF signal of a traveling-wave tube (TWT) was developed and integrated into a helical delay line. Its effect is shown in simulation and measurement.
Period variation in a filter helix TWT delay line
A filter consisting of periodic transmission line discontinuities to suppress the second harmonic in a traveling wave tube (TWT) is analyzed regarding the influence of its overall length and the length of a period on the stopband. The filter properties for varied period lengths are investigated. The focus is on spurious effects at the stopband edges and on the bandwidth.
Time lapse photography of clouds from high altitude balloons.
Time lapse pictures of clouds taken by cameras flown at altitudes of 30 km on balloons provide valuable insights into the convection and electrification of cloud systems. Simple camera arrangements for taking such pictures are described.