In general, the electrical characteristics of circuits associated with high-frequency instruments vary significantly with time. Signal sources, receivers, and interconnections drift with vibrations, cable flexing, temperature, humidity, and so forth. That’s why vector network analyzers (VNAs) are only treated as being time-invariant over short time periods (a few hours). Thus a VNA must be calibrated […]
FAQ
The difference between amplifier gain and antenna gain
Amplifier and antenna gain may sound the same, and both may be expressed in decibels, but they actually are measures of two different things. In an amplifier, gain is simply the ratio of the output divided by the input. Gain has no units as it is a ratio. However, amplifier gain is often expressed in […]
Going parabolic: The difference between a Ronchi, Foucault, and a Caustic test
Amateur astronomers like to build their own telescopes, sometimes to the point of even grinding the objective mirrors. This is doable, but involves purchasing the mirror blank plus various grades of grinding abrasives, polishing compounds and specialized tools. The lens must have a precise parabolic profile. It takes special test instruments to figure out whether […]
What’s all this triplen harmonics stuff?
Unless your background is in ac power, it’s possible you haven’t run into the term triplen harmonic. Triplen harmonics have to do with the third harmonic. Even-numbered harmonics do not normally exist in power systems due to symmetry between the positive and negative halves of the ac cycle. It is the odd-numbered harmonics that engineers […]
Quantifying and measuring non-electrical phenomena: Vibration
Vibration is an important design consideration in many electronic applications such as industrial, automotive, aerospace, and marine systems, and consumer white goods and disc drives. Even electronic devices designed for use in relatively vibration-free environments can be subjected to potentially damaging vibration during shipment. The concepts related to vibration also find utility in computer graphics, […]
The difference between LED and OLED displays
Despite some initial difficulties, it is reasonable to think that OLED (organic light emitting diode) displays will replace LCDs, making possible low-power flexible screens relatively inexpensive to manufacture. OLEDs have several advantages. For one thing, they can be made onto a suitable substrate by means of silk screen-printing or an inkjet printer. Roll-to-roll vapor deposition […]
Quantifying and measuring non-electrical phenomena: Humidity
Humidity is the concentration of water vapor in the air. Too much or too little humidity can be detrimental to the functioning of electronic devices. This FAQ begins by looking at some basic concepts related to humidity and the impact that humidity can have on electronics. It then looks at the importance of using humidity […]
Quantifying and measuring non-electrical phenomena: Heat
Heat involves the transfer of energy to or from a thermodynamic system. ‘Heat flow’, although commonly used, is a redundant term since heat is defined as the flow (or transfer) of thermal energy. Thermal energy is the kinetic energy of molecules and atoms. A Joule (J) is the International System (SI) unit of heat, work, […]
Quantifying and measuring non-electrical phenomena – Light
Light has varying definitions; it’s usually limited to the visible portion of the electromagnetic spectrum, but sometimes it’s defined to include the near-infrared (IR) and ultraviolet (UV) portions. For example, LidAR (light detection and ranging) uses various portions of UV, visible, or near IR spectrum to image objects. And ‘light’ has a different definition if […]
Now THAT’S a test instrument: Inside the Webb space telescope
The Hubble telescope, despite its initial optics crisis, was an enormously successful undertaking that answered far more questions about the universe than originally posed. Now comes the Webb space telescope, the most powerful telescope ever put into space and a successor to Hubble. If successful, it will look farther back in time, image fainter objects […]