This paper describes a millimeter-wave sensor that is able to detect pedestrians, thereby reducing the likelihood of human road injuries or fatalities. The sensor consists of a transmit/receive channel module, operating in the millimeter-wave range (W-band) using frequency-modulated-continuous-wave mode. The laboratory prototypes of the sensor have been designed and tested in real-life environment. An analysis of system performance and experiments conducted has indicated a high-resolution, detection ability of both adults and children at a distance of up to 100-150 m.

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 $(<\mathrm{}10\mathrm{}$ 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.

The paper describes millimeter wave (MMW) sensors designed for detecting both metallic and nonmetallic objects placed on a human body and hidden under clothes. The sensor is based on the synchronized detection principle and estimating a power of back-scattered signal from hidden objects. Time-gating algorithm combined with preliminary determined threshold level has been implemented in order to reach detection probability of ~ 90% or more for metal and plastic hidden objects at the distance up to 3 m.

A ferroelectric cathode is employed in a cyclotron-resonance maser (CRM). The CRM oscillator device operates at $\sim$ 7 GHz, near the cutoff frequency of a hollow cylindrical cavity. The cathode is made of a PLZT 12/65/35 ceramic with high-dielectric constant ${\mathrm{(\epsilon }}_r\text{∼4000).}$ Electrons are extracted from the plasma excited on the cathode surface by $\sim$ 1 kV short rise-time pulses. The use of ferroelectric cathodes may advance the microwave tube technology for various applications.

Ferroelectric cathodes were reported as a feasible electron source for microwave tubes. However, due to the surface plasma emission characterizing this cathode, operation of millimeter wave tubes based on it remains questionable. Nevertheless, the interest in compact high power sources of millimeter waves and specifically 95~GHz is continually growing. In this experiment, a ferroelectric cathode is used as an electron source for a gyrotron with the output frequency extended up to 95~GHz. Power above a 5~kW peak and $\sim${}0.5\,\,$\mu${}s pulses are reported; a duty cycle of 10% is estimated to be achievable.

Electron emission from ferroelectric cathodes is investigated, it is commonly suggested as an electron source for different applications due to its special characteristics such as high current density, easy treatment, and operation. In this experimental research, a lifetime of lead zirconate-titanate ceramic cathode with composition related to a ferroelectric phase was studied. The strong plasma emission from the cathode was excited in a nonreversal (nonswitching) mode by application of unipolar high stress. Severe damage to the cathodes was observed, especially in a high repetition rate. An upper limit of the lifetime of the ferroelectric cathode with plasma-induced emission was estimated at about ${\text{∼10}}^6$ pulses of ∼200 ns each at ∼100 Hz repetition rate. Possible applications of the limited lifetime ferroelectric cathode are discussed.