A.N. Panin

Millimeter-Wave Tunable Notch Filter Based on Waveguide Extension for Plasma Diagnostics

A millimeter-wave tunable notch filter using several extensions of the fundamental-mode rectangular waveguide has been developed to protect plasma diagnostics techniques from stray gyrotron radiation. The design utilizes the resonant behavior of the TE301 mode excited by cutoff coupling holes in a symmetrical smooth H-plane extension of waveguide. Proper choice of the shape and sizes of the coupling elements allows one to tune the operating frequency, notch depth, and notch band. Low-power experiments with the six-cavity filters show a maximal notch depth of below -120 dB at 70 and 170 GHz, and a notch depth of below -90 dB at frequency bands of 70 ± 0.05 and 170 ± 0.2 GHz. The filter design is rather simple and can be advanced into a higher frequency band up to the 400 GHz.

Superlattice harmonic mixer for submillimeter frequency synthesis

We report synthesized signal in 667-857 GHz frequency from synthesizer of 15-20 GHz range. The reference generator frequency is multiplied by 30-45 to BWO and FFO frequencies in subharmonic mixer with superlattices. This mixer is used at room temperature. The submillimeter signal power is less then 0.5 mW.

Design and test of new millimeter wave notch filter for plasma diagnostics

A new design of millimeter wave notch filter was suggested and tested. Fundamental waveguide notch filter consists of a smooth TE301 resonator with a coupling cut-off hole and a frequency tuning plunger. Six resonator notch filter was manufactured and measured. A numerical control machining was used to mill two identical half of the filter. In the experiment the only one resonance was observed in the 53.6 - 78.3 GHz frequency band. Power transmission of -90 dB was measured at 68 GHz, the notch band at the level -60 dB is 600 MHz. Frequency tuning of 0.5 GHz was also demonstrated.

Resonant notch filters based on rectangular waveguide extensions

Notch filters based on resonant reflection of the incident guided wave of a single-mode rectangular guide designed for frequencies of 28 and 70 GHz are numerically and experimentally studied. As shown by experiments, the 28 GHz two-sectioned resonant notch filter provides the attenuation of -60 dB at the central frequency f=28 GHz, more than -30 dB attenuation within the frequency band /spl delta/f=60 MHz and attenuation-free band up to 36 GHz. For the 70 GHz notch filter, the measured maximum attenuation is -60 dB at the operating frequency. The notch bandwidth at the level of -55 dB is 100 MHz. These characteristics allow use of the notch filters for protection of HF receivers of high sensitivity, for spectral measurements and other related purposes.

Development of the physical principles of the design and implementation of a 500–700 GHz spectrometer with a superconducting integrated receiver

A spectrometer based on the effect of freely decaying polarization in the frequency range 500–700 GHz has been designed. Radiation sources are harmonics from a quantum semiconductor superlattice frequency multiplier. The receiving system of this spectrometer is constructed using a superconducting integrated receiver based on a superconductor-insulator-superconductor mixer and a flux-flow oscillator operating as a heterodyne oscillator. The spectrometer has been used to measure absorption lines of NH3 in a sample of expired air (572 GHz).

Generation of high stable wide-range THz radiation for precise frequency measurements

High stable wide-range radiation sources (frequency synthesizers and generator of harmonics), operating up to 4.9 THz, are presented.

Analysis Of Noise Characteristics And Noise Generation In SubTHz And THz Frequency Ranges

Noise characteristics of subTHz and THz devices (mixers, detectors) based on Schottky diodes and quantum superlattice diodes (SL‐diodes) are presented. The test bench for measurements of device’s characteristics is elaborated. Noise generator of THz frequency range based on SL‐diodes multiplier and mm noise generator is also demonstrated.

Solid-state non-stationary spectroscopy of 1–2.5 THz frequency range

The advantages of using high precision, time-domain spectroscopy in THz frequency range are presented. The advantages of application of solid-state sources (synthesizers) of millimeter wavelength with PLL of reference generator and frequency multipliers on quantum semiconductor structures are shown. The results of measurements of spectral distribution after multiplier are presented.

Fast sweep solid state spectrometer for sub-THz and THz frequency ranges

The design and development of a fast sweep submillimeter and THz spectrometer based on solid-state components is presented. A prototype laboratory model of such a spectrometer will be described and some performance characteristics as well as potential applications emphasized.

Solid state nonstationary spectrometers SUBTHz and THz frequency ranges for analytical applications

In the paper we present a new approach to development of a time-domain (pulse Furier-transform) spectroscopy method in subTHz and THz frequency ranges with maximal sensitivity and spectral resolution. In our studies we obtained harmonics up to 2.7 THz with application of multipliers based on quantum superlattice structures. Our spectrometer includes subTHz and THz emission sources based on phase-stabilized Gunn generators and quantum superlattice structures multipliers and mixers (up-converter). This approach ensures narrow instrumental linewidth less than 10 kHz over the operating range of the spectrometer as well as development of software for computer control and data acquisition. In the paper we propose two possible schemes of spectrometers realization. These variants of spectrometer are suitable, in particular, for atmospheric investigations, including detection of water, acetone, NO, CO etc.