Related Experiment Video
Updated: Feb 9, 2026
13:31
High Speed Sub-GHz Spectrometer for Brillouin Scattering Analysis
Published on: December 22, 2015
15.7K
Low noise 874 GHz receivers for the International Submillimetre Airborne Radiometer (ISMAR)
A Hammar1, P Sobis1, V Drakinskiy2
1Omnisys Instruments AB, August Barks Gata 6B, SE-421 32 Västra Frölunda, Sweden.
The Review of Scientific Instruments
|June 6, 2018
Summary
Researchers developed two 874 GHz receiver channels for airborne radiometry, achieving a 3300 K noise temperature. Optimization with a dielectric lens reduced noise by 200 K, enhancing submillimeter wave detection capabilities.
Area of Science:
- Submillimeter wave technology
- Radio astronomy instrumentation
- Atmospheric remote sensing
Background:
- The International Submillimetre Airborne Radiometer requires high-performance receiver channels for atmospheric observations.
- Developing sensitive receivers at 874 GHz presents significant engineering challenges.
Purpose of the Study:
- To design and characterize two orthogonal polarization receiver channels operating at 874 GHz.
- To evaluate the impact of dielectric lens materials on receiver performance.
- To assess the overall system noise temperature and radiation pattern.
Main Methods:
- Integration of a spline horn antenna, dielectric lens, Schottky diode mixer, and IF low noise amplifier within a split block housing.
- Noise temperature measurements across a 10 GHz intermediate frequency (IF) band at varying operational temperatures.
- Evaluation of three dielectric lens materials for their effect on radiation patterns and noise temperature.
- Characterization of local oscillator (LO) chains, including Schottky diode quadruplers and heterostructure barrier varactor (HBV) triplers.
- Radiation pattern measurements and return loss analysis using network analyzers.
Main Results:
- Achieved a mean double sideband (DSB) noise temperature of 3300 K at 40 °C across a 10 GHz IF band.
- A minimum DSB noise temperature of 2260 K was measured at 20 °C without a lens.
- One dielectric lens material reduced noise temperature by approximately 200 K with an estimated loss of 0.42 dB.
- Radiation patterns exhibited a symmetric main beam lobe (<5° FWHM) and side lobes below -20 dB.
- Return loss measurements showed reflections below -25 dB, primarily at the waveguide interface.
Conclusions:
- The developed 874 GHz receiver channels meet the performance requirements for airborne submillimeter radiometry.
- Dielectric lens optimization significantly improves receiver sensitivity, with specific materials offering superior performance.
- The integrated design ensures robust performance with well-defined radiation characteristics suitable for atmospheric studies.
More Related Videos
Related Concept Videos
02:00Internal Energy
36.8K
The total of all possible kinds of energy present in a substance is called the internal energy (U), sometimes symbolized as E. Suppose a system with initial internal energy, Uinitial, undergoes a change in energy (transfer of work or heat), and the final internal energy of the system is Ufinal. Change in internal energy equals the difference between Ufinal and Uinitial.
36.8K
01:29Internal Energy
7.1K
The internal energy of a thermodynamic system is the sum of the kinetic and potential energies of all the molecules or entities in the system. The kinetic energy of an individual molecule includes contributions due to its rotation and vibration, as well as its translational energy. The potential energy is associated only with the interactions between one molecule and the other molecules of the system. Neither the system's location nor its motion is of any consequence as far as the internal...
7.1K
01:31Internal Receptors
74.7K
Many cellular signals are hydrophilic and therefore cannot pass through the plasma membrane. However, small or hydrophobic signaling molecules can cross the hydrophobic core of the plasma membrane and bind to internal, or intracellular, receptors that reside within the cell. Many mammalian steroid hormones use this mechanism of cell signaling, as does nitric oxide (NO) gas.
74.7K
01:15Receiver Operating Characteristic Plot
491
A ROC (Receiver Operating Characteristic) plot is a graphical tool used to assess the performance of a binary classification model by illustrating the trade-off between sensitivity (true positive rate) and specificity (false positive rate). By plotting sensitivity against 1 - specificity across various threshold settings, the ROC curve shows how well the model distinguishes between classes, with a curve closer to the top-left corner indicating a more accurate model. The area under the ROC curve...
491
01:25Transmission-based Precautions II: Airborne and Protective Environment
2.0K
Transmission-based precautions are for patients infected or suspected to be infected (or colonized) with organisms posing a significant risk to others. The transmission precautions include airborne and protective environment precautions.
Airborne precautions:
Use airborne precautions when treating patients known or suspected to have diseases that spread through the air—for example, tuberculosis or measles. These organisms are present in smaller droplets expelled by an infected person and...
Airborne precautions:
Use airborne precautions when treating patients known or suspected to have diseases that spread through the air—for example, tuberculosis or measles. These organisms are present in smaller droplets expelled by an infected person and...
2.0K
01:29International System of Units
5.1K
The International System of Units, known as the SI system, is a universally accepted measurement system recognized and used worldwide. The SI system is based on a set of three base units considered absolute, and their values do not change with location. These base units are meters, kilograms, and seconds.
Prefixes are used to define both larger and smaller quantities in the SI system. For example, milli, micro, and nano define smaller quantities, while kilo, mega, and giga are used to define...
Prefixes are used to define both larger and smaller quantities in the SI system. For example, milli, micro, and nano define smaller quantities, while kilo, mega, and giga are used to define...
5.1K