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We report the first applications of the quasioptical (QO) code PARADE (PAraxial RAy DEscription) for modeling the electron cyclotron emission (ECE) diagnostic. Geometrical optics (GO) has been exploited to predict the ECE intensity received by an antenna, but is not sufficient since GO drops the information lying on the transverse cross section of the antenna sensitivity. Hence, we studied a QO model of ECE measurement based on the PARADE code. By introducing a weighting operator W ˆ , induced by the envelope profile of a wave beam virtually injected from an ECE receiving antenna, an integral equation, formally identical to the conventional GO model, is newly derived from the wave-action conservation law. A QO ECE prediction module −E3 is also newly developed, is applied to the JT-60SA tokamak, and shows that radiation temperature is corrected from conventional GO prediction. The −E3 module and the PARADE code are applicable to any fusion plasma devices. By using this ECE prediction package, more realistic calculations of radiation temperature are expected by taking the actual structure of an ECE receiving antenna and plasma parameters as well. [ABSTRACT FROM AUTHOR]

Subject and purpose. Open resonant system as the oscillating circuit of the solid-state oscillators and characteristics of the quasi-optical oscillators properly are the object of investigations. Purpose of article is review of works being fulfilled at the solid-state department over period 1979 and to the present day. The intent of the paper is to give the indication prerequisites of the creation of high-stabilized millimeter wave sources and way of this problem solution. Method and methodology. Theoretical and experimental methods of study of main parameters of open resonators with resonant and nonresonant inhomogeneities such as spectrum, field topology of open resonators are the waveguide model of resonator, decomposition method, generalized scattering matrix method, and experimental technique of the power, frequency, and spectrum measurements. Results. Results of study and development of quasi-optical solid-state oscillator are: the level of frequency noise is no more than –115…120 dB/Hz; power of generation at first harmonic is up to 130…150 mW at frequency of 40…50 GHz; at second harmonic – up to 10 mW at 60…90 GHz; generation power is no more than 3 mW at frequency of 150 GHz ; long-term frequency instability is 3×10–8 at active control temperature DТ ~ 0.1 °С. Conclusion. In the paper it is analyzed an application area of solid-state oscillators. They are local oscillators in receiving units and radiometers, refractometry, dielectro-metry, and fields where high stability and low level of frequency noise are needed. The promising lines are inquired, they are search of new physical properties for nonlinear element creating at Terahertz frequency band.

[Display omitted] • Extended Interaction Klystron was integrated with a 200 GHz quasioptical bridge. • Electron detection was performed in homodyne induction mode. • B 1e fields of up to 30 MHz have been measured by echo nutation experiments. • Room-temperature DNP enhancements were characterized for a variety of samples. • The constructed instrument paves the way for future pulse DNP experiments. One of the most essential prerequisites for the development of pulse Dynamic Nuclear Polarization (DNP) is the ability to generate high-power coherent mm-wave pulses at the electron precession frequencies corresponding to the magnetic fields of modern high-resolution NMR spectrometers. As a major step towards achieving this goal, an Extended Interaction Klystron (EIK) pulse amplifier custom-built by the Communications and Power Industries, Inc. and producing up to 140 W at 197.8 GHz, was integrated with in-house built NMR/DNP/EPR spectrometer operating at 7 T magnetic field. The spectrometer employs a Thomas Keating, Ltd. quasioptical bridge to direct mm-waves into a homebuilt DNP probe incorporating photonic bandgap (PBG) resonators to further boost electronic B 1e fields. Three-pulse electron spin echo nutation experiments were employed to characterize the B 1e fields at the sample by operating the homodyne 198 GHz bridge in an induction mode. Room-temperature experiments with a single-crystal high-pressure, high-temperature (HPHT) diamond and a polystyrene film doped with BDPA radical yielded < 9 ns π/2 pulses at ca. 50 W specified EIK output at the corresponding resonance frequencies and the PBG resonator quality factor of Q ≈300. DNP experiments carried out in a "gated" mode by supplying 20 μs mm-wave pulses every 1 ms yielded 13C solid-effect DNP with gains up to 20 for the polystyrene-BDPA sample at natural 13C abundance. For a single-crystal HPHT diamond, the gated DNP mode yielded almost the same 13C enhancement as a low-power continuous wave (CW) mode at 0.4 W, whereas no DNP effect was observed for the BDPA/polystyrene sample in the latter case. To illustrate the versatility of our upgraded DNP spectrometer, room-temperature Overhauser DNP enhancements of 7–14 for 31P NMR signal were demonstrated using a liquid droplet of 1 M tri -phenyl phosphine co-dissolved with 100 mM of BDPA in toluene‑ d 8. [ABSTRACT FROM AUTHOR]

Purpose: The possibility of creating a broadband polarization rotator for the long-wave terahertz range is studied. Design/methodology/approach: To achieve the purpose set the results of the work done have been used where tunable and broadband differential phase sections consisting of several birefringent elements were considered using the method of polarization scattering matrix. Findings: It is shown that the use of the broadband differential phase sections can significantly extend the operating frequency range of the polarization rotator. Conclusions: The experimental study confirmed the possibility of creating a broadband polarization rotator. Artificial dielectrics which have a so-called form birefringence property were applied as the birefringent elements.

Purpose: Studying the quasioptical tunable and broadband differential phase section (DPS) consisting of several birefringent elements (BE) on the basis of form birefringence effect. Design/methodology/approach: Using the polarization scattering matrix method, the impact of the mutual rotation axis of anisotropy of several BE by the amount of phase shift and the position of the plane of anisotropy of resulting DPS is considered. Findings: The DPS tunable in a wide range are shown to be possibly implemented in the case of quarter-wave DPS of two, and in the case of half-wave DPS of three, identical non-tunable BE. The analysis has shown to the possibility of creating a broadband quarter-wave and half-wave DPS. Сonclusions: Experimental research has confirmed the possibility of constructing a tunable and broadband DPS. On this basis, tunable and broadband polarization converters, rotators of polarization plane, polarization phase shifters and frequency shifters in the terahertz frequency range can be created.

When constructing polarization radio measuring paths operating in the THz frequency range (0.1…10 THz) the differential phase sections (DPS) are widely used. The use of terahertz waves (THz) allows research in radio astronomy, radio spectroscopy, biology, medicine, physics of the atmosphere, etc. Due to the fact that in a terahertz wave range quasi-optical transmission lines are used the transfer to the optical principles of construction DPS using dielectrics having birefringence property, in particular, form birefringence seems to be very attractive. One of the important requirements when creating the DPS is their matching with free space. The paper represents the ways of matching structures with form birefringence in the form of a multilayer stack of alternating dielectric plates with different dielectric constants. Such an antireflection layer may be formed when one of the plates is projected over the surface of the birefringent dielectric structure. In the first case projecting plates have transverse grooves. In the second case plates are formed without grooves. For the calculation of such structures we used a numerical method of integral functionals in the frequency domain for full wave dispersion problem of plane monochromatic wave scattering from a lattice consisting of dielectric bars without loss. An experimental study of models of structures, which confirmed the possibility of matching with the methods discussed in the THz range was made.

Analysing Feynman integral for one-dimensional harmonic oscillator we have found that it is possible to introduce quasiparticle of radio systems. This quasiparticle we have called radion. One can understand radion as object moving along fractal trajectories in phase space of oscillator. The same arguments have led us to the conclusion about natural fractality of all radio systems working with spectrum of signal. Under radiation of electromagnetic wave into medium with arbitrary dielectric permeability radion continues its fractal movement. Interrelations of radion and photon also have been discussed.

Graphical abstract Highlights • A frequency-agile 200 GHz/300 MHz DNP NMR spectrometer was constructed. • The spectrometer is based on solid-state mm-wave devices and quasioptical components. • 200 GHz photonic band gap resonator was integrated into double-tuned NMR saddle coil. • 13C DNP enhancement of ca. 1500 was obtained in synthetic diamond crystals at room temperature. • Resonator probehead provides the same electronic B 1 at up to 11 dB lower incident power. Abstract The most critical condition for performing Dynamic Nuclear Polarization (DNP) NMR experiments is achieving sufficiently high electronic B 1e fields over the sample at the matched EPR frequencies, which for modern high-resolution NMR instruments fall into the millimeter wave (mmW) range. Typically, mmWs are generated by powerful gyrotrons and/or extended interaction klystrons (EIKs) sources and then focused onto the sample by dielectric lenses. However, further development of DNP methods including new DNP pulse sequences may require B 1e fields higher than one could achieve with the current mmW technology. In order to address the challenge of significantly enhancing the mmW field at the sample, we have constructed and tested one-dimensional photonic band-gap (PBG) mmW resonator that was incorporated inside a double-tuned radiofrequency (rf) NMR saddle coil. The photonic crystal is formed by stacking ceramic discs with alternating high and low dielectric constants and thicknesses of λ/4 or 3λ/4, where λ is the wavelength of the incident mmW field in the corresponding dielectric material. When the mmW frequency is within the band gap of the photonic crystal, a defect created in the middle of the crystal confines the mmW energy, thus forming a resonant structure. An aluminum mirror in the middle of the defect has been used to substitute one-half of the structure with its mirror image in order to reduce the resonator size and simplify its tuning. The latter is achieved by adjusting the width of the defect by moving the aluminum mirror with respect to the dielectric stack using a gear mechanism. The 1D PBG resonator was the key element for constructing a multi-resonant integrated DNP/NMR probehead operating at 190–199 GHz EPR/300 MHz 1H/75.5 MHz 13C NMR frequencies. Initial tests of the multi-resonant DNP/NMR probehead were carried out using a quasioptical mmW bridge and a Bruker Biospin Avance II spectrometer equipped with a standard Bruker 7 T wide-bore 89 mm magnet parked at 300.13 MHz 1H NMR frequency. The mmW bridge built with all solid-state active components allows for the frequency tuning between ca. 190 and ca. 199 GHz with the output power up to 27 dBm (0.5 W) at 192 GHz and up to 23 dBm (0.2 W) at 197.5 GHz. Room temperature DNP experiments with a synthetic single crystal high-pressure high-temperature (HPHT) diamond (0.3 × 0.3 × 3.0 mm3) demonstrated dramatic 1500-fold enhancement of 13C natural abundance NMR signal at full incident mmW power. Significant 13C DNP enhancement (of about 90) have been obtained at incident mmW powers of as low as <100 μW. Further tests of the resonator performance have been carried out with a thin (ca. 100 μm thickness) composite polystyrene-microdiamond film by controlling the average mmW power at the optimal DNP conditions via a gated mode of operation. From these experiments, the PBG resonator with loaded Q ≃ 250 and finesse F ≈ 75 provides up to 12-fold or 11 db gain in the average mmW power vs. the non-resonant probehead configuration employing only a reflective mirror. [ABSTRACT FROM AUTHOR]

The quasioptical theory is generalized for approximate analytical description of refraction and diffraction focusing of multimode beams of narrowband pulse radiation in oceanic waveguides stratified over depth. General regularities of joint manifestation of spatial focusing and dispersion-induced compression of frequency-modulated pulsed signals during propagation of multimode beams are analyzed. [ABSTRACT FROM AUTHOR]

The design and analysis of a blackbody radiation calibrator, coupled quasioptically to a millimeter or submillimeter band detector antenna, are described. A calculation and optimization of the parameters of the cryogenic black body with a modulated temperature for testing a new type of TES bolometer, connected in an integrated immersion 200-300 GHz band lens antenna, are presented. [ABSTRACT FROM AUTHOR]

Abstract: We describe the optical design and performance of ’QUEST and DASI’ or ’QUaD’, a ground-based high-resolution experiment designed to measure the polarisation properties of the cosmic microwave background radiation. QUaD uses bolometric detectors at 100 and 150GHz on a 2.6m Cassegrain telescope. The QUaD optics are designed to minimise systematic effects as well as to maximise sensitivity, and we report here on the comprehensive quasi-optical analysis used to achieve this design. We also present initial optical performance measurements achieved in operation, and discuss changes made to the optics to overcome some errors in the mechanical construction of the primary mirror. The QUaD experiment is now fully operational and taking world-leading data at the South Pole. [Copyright &y& Elsevier]

In this paper, we present the quasioptics of a millimetre wave radiometer for the remote sensing of atmospheric water vapour. The presented work addresses the design of the quasioptics with special emphasis on the verification of theoretical aspects by measurements of phase, amplitude and polarisation. The optical behaviour of a quasioptical isolator and a Martin–Puplett interferometer for the suppression of the undesired sideband is discussed in detail. It is shown that the optical behaviour of a rooftop mirror is different from what is theoretically expected. [Copyright &y& Elsevier]

This paper is about the early quasioptics of near-millimeter and submillimeter waves in IRE-Kharkov (Institute of Radio Physics and Electronics of the National Academy of Sciences of Ukraine) and the development of the hollow dielectric beam-waveguide (HDB) technology and measuring techniques of the near-millimeter and submillimeter wavelength ranges, with main application in hot plasma diagnostics. It presents the details of the development based on the declassified reports and the interviews of Y.M. Kuleshov and another key member of the quasioptics (QO) team, M. S. Yanovski. Y.M. Kuleshov and his team had already accumulated rich experience in developing waveguide measuring devices in the whole millimeter-wave range between 1954 and 1961. In 1994-1996, the research project "Ozero" was carried out with Y.M. Kuleshov as a principal investigator. The aim of the "Ozero" was to explore the feasibility of developing a kit of HDB-based measuring devices in the wavelength range λ = 0.7 to 1.7 mm. After the finish of "Ozero", in 1968-1971, the next R&D project called "Oliva" was granted by the same directorate of MRI. Its idea was to dwell on and refine the polarization principles in the measuring circuits for λ = 0.5-0.8 mm. HDB was patented only in 1969. Since the 1970s, the activities of the QO department were focused entirely on the development of HDB-based instruments and systems. Here, the major application area was hot plasma diagnostics in new large Tokamaks. They also dwelled in the development of the measuring techniques including reflectometry and polarimetry. Other HDB based systems elaborated in IRE include radars in the 1970-1980s and RCS testing ranges in the 1990s. [ABSTRACT FROM PUBLISHER]

YBCO integrated structures consisting of a planar antenna and a Josephson junction were designed and fabricated on bicrystal sapphire substrates. By combining two such structures in an oscillator-receiver arrangement a submillimeter-wavelength tester was realised. Two types of relatively narrow-band double-slot and double-dipole antennas, a broadband complementary log-periodic antenna and an array of dipole antennas were investigated. [Copyright &y& Elsevier]

Defocused Gaussian beam telescope geometry and its tolerance with the changes in the values of their lenses and focalization distances are analyzed. The Gaussian beam telescope is very useful in systems that must operate over broad bandwidths. This device has particularly functional properties in Cassegrain radiotelescope feed systems. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 32: 420–423, 2002. [ABSTRACT FROM AUTHOR]

The paper considers an optimum sectional waveguide taper (OSWT) which at a shortest length of the transition region provides nearly adiabatic propagation of the fundamental mode between circular, widely different in diameter quasioptical transmission lines of class “hollow dielectric waveguide” (HDW). Derived as a consequence of coaxial circular-horn sections, the OSWT offers all the advantages of a simple geometry and lends itself to simple fabrication techniques. The relationships among the critical geometrical parameters and the loss calculation formulae are presented. The comparison studies show that even at a few sections, the OSWT is almost as good in performance as the parabolic taper, but the OSWT is much better from a mechanical viewpoint. And compared to the ordinary linear taper, the OSWT allows essential cut in length and loss with the broadbandness kept. The HDW-based four-sectional OSWT has been fabricated and tested in a quite broad wave range 2,5-8 mm. The testing results lend a good support to the analytical formulae lying at the basis of the design software. [ABSTRACT FROM AUTHOR]

Experimental results for an open resonator fed by a rectangular waveguide in the 18-20-GHz frequency band are presented. The data are compared with theoretical results arising from the mode-matching approach to the problem to give a simple equivalent circuit. [ABSTRACT FROM AUTHOR]

• Several configurations of PBG resonators in the DNP probehead were characterized. • The gain in mm-wave power at the sample has been improved to 50-fold vs. mirror-only setup. • The gains strongly depend on the arrangement of dielectric layers next to the sample. • Odd-numbered arrangements represent a promising avenue for further boosting the mmW power gain. • Results are rationalized in terms of effective finesse and finite-element simulations. Polarization of nuclear spins via Dynamic Nuclear Polarization (DNP) relies on generating sufficiently high mm-wave B 1e fields over the sample, which could be achieved by developing suitable resonance structures. Recently, we have introduced one-dimensional photonic band gap (1D PBG) resonators for DNP and reported on prototype devices operating at ca. 200 GHz electron resonance frequency. Here we systematically compare the performance of five (5) PBG resonators constructed from various alternating dielectric layers by monitoring the DNP effect on natural-abundance 13C spins in synthetic diamond microparticles embedded into a commercial polyester-based lapping film of just 3 mil (76 μm) thickness. An odd-numbered configuration of dielectric layers for 1D PBG resonator was introduced to achieve further B 1e enhancements. Among the PBG configurations tested, combinations of high- ε perovskite LiTaO 3 together with AlN as well as AlN with optical quartz wafers have resulted in ca. 40 to over 50- fold gains in the average mm-wave power over the sample vs. the mirror-only configuration. The results are rationalized in terms of the electromagnetic energy distribution inside the resonators obtained analytically and from COMSOL simulations. It was found that average of B 1 e 2 over the sample strongly depends on the arrangement of the dielectric layers that are the closest to the sample, which favors odd-numbered PBG resonator configurations for their use in DNP. [ABSTRACT FROM AUTHOR]

Enhanced millimeter wave transmission through a subwavelength slot placed into a corrugated conducting wafer, using perfect conductor model, is experimentally observed compared with the case of the single isolated slot. The corrugated wafer responds in a similar way as in the optical regime, in which a surface plasmon model is employed to describe the metal. Experimental results of the enhanced transmission and reflection of the corrugated wafer have been measured by using a quasioptical vector network analyzer. Future applications of enhanced subwavelength transmission in quasioptical devices are envisaged. [ABSTRACT FROM PUBLISHER]

Active antenna elements consisting of FET oscillators integrated with notch antennas have been used to create a 3 x 3 quasioptical power combining array. The array has a good power combining efficiency and a well-defined main beam. The design of the FET active notch antenna element and the performance of the 3 x 3 array are discussed. [ABSTRACT FROM AUTHOR]

A two-grid approach for quasioptical bandpass filter design is presented. In this design, an inductive/capacitive grid on one side of a dielectric substrate is transformed to an effective capacitive/inductive reactance at the other grid plate, producing a parallel resonant circuit. Two bandpass filters for use in the millimeter region have been fabricated. Low-loss power transmission at the design frequencies has been achieved with good quantitative agreement with theory. [ABSTRACT FROM AUTHOR]

This paper presents a novel THz optical design that allows the acquisition of THz reflectivity maps of in vivo cornea without the need for a field flattening window and preliminary imaging results of in vivo rabbit cornea. The system's intended use is to sense small changes in corneal tissue water content (CTWC) that can be precursors for a host of diseases and pathologies. Unique beam optics allows the scanning of a curved surface at normal incidence while keeping the source detector and target stationary. Basic system design principles are discussed and image sets of spherical calibration targets and corneal phantom models are presented. The presented design will enable, for the first time, non-contact THz imaging of animal and human cornea.