Millimeter-Wave Band Multi-Mirror Open Resonator. E- and H- Polarized Oscillations
This work provides the experimental research results of E- and H-polarized oscillations of the complex multi-mirror open resonator (OR) , one of the mirrors of which is represented by the echelette reflective grating. The essential difference between the spectra of E- and H- polarized oscillations of complex open resonator (COR) is noted. It is evident that within the range of measurements performed for the H-polarization, only one oscillation mode is excited while in the case with the E-polarization there are excited several of such modes. In this case the self-collimation reflection from the echelette grating determines the conditions for excitation of the OR, which condition is the dispersive element forming up the OR spectrum. Some functional capabilities implied by the design of the suggested multi-mirror open resonant system are also discussed. The suggested multi-mirror open resonant system can find wide application in millimeter-wave band electronics for frequency stabilization of the electron-vacuum and solid-state devices.
MM-wave range oscillator with a multi-mirror open resonator
The millimeter wavelength range generator with four-mirror open resonator is described. The frequency and energy characteristics of the generator are investigated.
New Low-Profile Applicators for Local Heating of Tissues
A new type of low-profile applicator is described giving efficient power transfer to tissue with low leakage. It consists of a resonant element spaced from a ground plane by low-loss material having high relative permittivity and some relative permeability. This combination is covered by similar material which can be placed in direct contact with the tissue to be heated, or separated from it by a water bolus as required. Laboratory measurements using phantom materials show that these applicators are well matched and produce well defined and relatively uniform heating profiles. Applicators having maximum dimensions of 3-15 cm covering the frequency range 1000-100 MHz, respectively, are described. Penetration depths of at least 4 cm at 100-200 MHz are achieved. Tests on anesthetised pigs and some clinical assessment have confirmed the usefulness of this compact low-frequency type of applicator and have shown that performance compares favorably with that of other recently reported types. The design can be optimized for treatment of specific sites, and suitable choice of dimensions and electrical characteristics of the layer material allow the low-profile concept to be extended over a wide range of operating frequencies.