Normal and anomalous Doppler effects in a dielectric-loaded stripline cyclotron-resonance maser oscillator

The slow-wave cyclotron-resonance master (CRM) oscillator experiment presented in this paper produces output signals that correspond to normal and anomalous Doppler shifts. The table-top low-voltage $(<10$ kV) CRM device consists of a double stripline waveguide. The metal strips are loaded by dielectric slabs; thus the waveguide supports slow waves with different phase velocities in odd and even quasi-TEM modes. The suppression of axial electric-field components in this waveguide eliminates the Cherenkov interaction as a parasitic effect to the slow-wave CRM. Oscillations are observed in the frequency range 3--15 GHz. Doppler shifts of 30% down and 150% up are measured with respect to the electron cyclotron frequency. These agree with the normal and anomalous tuning conditions, respectively. The dielectric-loaded stripline scheme is discussed for practical slow-wave CRM devices.