Most engineers today are sensitive to problems that arise when digital measurement instruments try to capture signals containing frequencies that are too high for the sampling circuitry to handle–undergrad EE programs typically cover Nyquist’s sampling theorem. Nevertheless, there are terms associated with sampling problems that sometimes get confused. Probably the three concepts most likely to […]
Difference between a waveguide and transmission line
As electronics migrates to higher and higher frequencies, the media routing electronic signals to their intended destinations grow increasingly exotic. This is particularly true as communication technology moves to 5G frequencies which are characterized by millimeter wave transmissions. In this frequency range, engineers are more likely to encounter waveguides and transmission lines rather than ordinary […]
The difference between the Faraday effect and Faraday’s law of induction
Michael Faraday is probably best known for his law of induction. But he also discovered the Faraday Effect in 1845 which states that light and electromagnetism are related phenomena. Faraday asserted that, in fact, light is a form of electromagnetism, anticipating James Clerk Maxwell by nearly two decades. Faraday stated that when a solid or […]
Does Kirchhoff’s Voltage Law really fail?
Gustav Kirchhoff (1824-1887) was an accomplished Prussian physicist and instrument maker, and best known for his current and voltage circuit laws. Kirchhoff’s first circuit law, known as his current law, states that the algebraic sum of currents in a network of conductors meeting at a point is zero. Kirchhoff’s second circuit law, known as his […]
What is Fourier transform IR spectroscopy?
Most EEs probably think of a Fourier transform in terms of an operation that converts time-based waveforms on a scope into their component frequencies. But Fourier transforms also play a role in infrared spectroscopy. It might be easiest to explain Fourier transform infrared spectroscopy by contrasting it with conventional spectroscopy. Also called “dispersive spectroscopy,” the […]
The difference between VSWR and the S11 reflection coefficient
A traveling signal along an electrical transmission line reflects back toward the source when one or more events occurs: One or both of the conductors is open at the far end (receiving end). The conductors are shorted at the far end (very common). There is a discontinuity in the characteristic impedance or an electrical fault […]
Electric charge and instruments used to measure it
Many devices have been built for measuring electric charge. One of the first was the gold-leaf electroscope. When a charged object touches the metal knob at the outer end of the rod, the charge flows down to the leaves. The leaves diverge due to the repulsion of like charges they have received. The degree of […]
What’s all this double-slit photon stuff?
Newton’s corpuscular theory of light was the accepted model of light propagation in the 17th and 18th centuries. The double-slit experiment, first performed by Thomas Young in 1801, seemed to revive the wave theory of light. In the modern version of this experiment, a coherent light source such as a laser is aimed at an […]
When oscillators didn’t contain op amps
Examine a discrete oscillator circuit today and you’ll likely find an operational amplifier with components in a feedback loop that cause the oscillation. In many cases, oscillators implemented with op amps are updated versions of designs that formerly used odd-ball components such as neon bulbs and delay lines to get the required phase shift needed […]
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 […]
