Microwave detectors

Fig. 1 shows the block diagram of the vibrometer, in which the most sensible to small phase variations interferometric scheme is employed. It consists of the microwave and the display units. The display unit consists of the power supply 1, controller 2 of the phase modulator 3, microprocessor unit 9 and low-frequency amplifier 10. The microwave unit contains the electromechanical phase modulator 3, a solid-state microwave oscillator 4, an attenuator 5, a bidirectional coupler 6, a horn antenna 7 and a microwave detector 11. The horn antenna is used for transmitting the microwave and receiving the reflected signal, which is mixed with the reference signal in the bidirectional coupler. In the reference channel the electromechanical phase modulator is used to provide automatic calibration of the instrument. To adjust the antenna beam to the object under test, the microwave unit is placed on the platform which can be shifted in vertical and horizontal planes. 

A classical setup for microwave conductivity measurements is based on the utilization of the waveguides. A simple installation consists of a microwave generator (typically a gun diode) which, when the Ka-band is used, can be operated in the frequency region of 28-40 Gc/s this is protected by an isolator against back-reflections from the rest of the microwave circuit. The microwave power is conducted by an attenuator across a circulator into the microwave conductor branch at the end of which the electrochemical cell is mounted. The microwave power reflected from the electrochemical sample is conducted via the circulator into the microwave detector. It typically consists of a diode that acts as an antenna, receiving the electrical alternating field, rectifying it, and con-... 

Microwave detectors Emit ultra-high-frequency radio waves, and the detector senses any changes in these waves as they are reflected throughout the protected space. Microwaves can penetrate through walls, and thus a unit placed in one location may be able to protect multiple rooms. 

Most UV equipment operates at voltages well above the main level, and it is important to prevent exposure to high voltage by proper installation. Microwave-powered lamps have a microwave detector to detect microwave radiation leakage. The system is shut down when microwave irradiance of 5 mW/cm is detected. ... 

An interesting potential application of Rydberg atoms is as a far infrared (or microwave) detector, a notion first suggested by Kleppner and Ducas.37 The basic... 

Test microwave leakage with a microwave detector with a low sensitivity range. 

Figure 6-11. Schematic of plasma-chemical microwave system with magnetic field (1) plasma-chemical reactor (2) converter of type of electromagnetic wave (3, 4) solenoids (5) vacuum pump (6) liquid nitrogen trap (7) refrigerator, (8) gas tanks (9) control volumes (10) vacuum-meter (11, 12) differential manometers (13) waveguide branching system (14) spectrograph (15, 16) microwave detectors (17) semi-transparent mirror (18) photo-electronic amplifier (M) magnetron microwave source (K) klystron microwave source (S) window for diagnostics.

Such a study would require the use of low noise quantum limited microwave detectors. 

Both Fourier-transform (FT) and continuous-wave (CW) EPR spectrometers are available. The FT-EPR instrument is like an FT-NMR spectrometer except that pulses of microwaves are used to excite electron spins in the sample. The layout of the more common CW-EPR spectrometer is shown in Fig. 13.38. It consists of a microwave source (a klystron or a Gimn oscillator), a cavity in which the sample is inserted in a glass or quartz container, a microwave detector, and an electromagnet with a field that can be varied in the region of 0.3 T. The EPR spectrum is obtained by monitoring the microwave absorption as the field is changed, and a typical spectrum (of the benzene radical anion, CgHj) is shown in Fig. 13.39. The peculiar appearance of the spectrum, which is in fact the first... 

Interstellar spectroscopy is usually carried out with a single-dish radio telescope composed of a precision parabolic reflector with a highly sensitive microwave detector at the focal point of the reflector. Molecular identifications, usually via rotational emission frequencies, are made by comparison with precise laboratory frequency measurements or frequency predictions. Microwave spectroscopy plays a very important role in providing the data for identification of new molecular species. Identifications have been made mostly with data in the microwave. 

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