| Date |
Fact of the Day Topic |
| July 1 |
Hertzian Waves In 1887, Heinrich (Rudolph)
Hertz verified James C. Maxwell's 1864 theory that electrical disturbances
should propagate through ... |
| July 2 |
Photoelectric Effect Discovery Heinrich
Herz was a Professor of Physics at Karlsruhe and Bonn. In 1887 one his
students, Wilhelm Hallwachs ... |
| July 3 |
1880 Optical Telephone Transmission Patent Alexander
Graham Bell and Sumner Tainter were granted a U.S. patent in 1880 for
a wireless ... |
| July 4 |
The Edison Effect Thomas Edison created
a vacuum-tube diode in 1883, but didn't understand how it worked or appreciate
what could be done with it ... |
| July 5 |
Diode and Triode Vacuum Tube Development University
College (London) Professor John Ambrose Fleming was employed by
the Marconi Company ... |
| July 6 |
First Voice Radio Transmission Professor
Reginald Aubrey Fessenden was the first person to successfully transmit
human voice by radio. The transmission ... |
| July 7 |
Heterodyne Signal Detection Invention Communication
receivers use a Beat Frequency Oscillator (BFO) to make unmodulated continuous
wave ... |
| July 8 |
Superheterodyne Invention The earliest
radio receivers consisted merely of RF amplitude-detectors of various
kinds connected to antennas. The detectors ... |
| July 9 |
The First Radio Commercial New York
radio station WEAF (which later became WNBC) was the first to
transmit a radio commercial ... |
| July 10 |
Yagi Antenna Invention If asked, many
who have studied electronics would tell you Yagi antennas were invented
by someone named Yagi ... |
| July 11 |
Speech Clipping Consonants contain
the majority of the intelligence information in speech (the portion
that makes it possible to understand ... |
| July 12 |
Superheterodyne Spurious Responses The
intermediate-frequency filter selectivity of a superheterodyne receiver
is not a complete indication ... |
| July 13 |
Speech Articulation and Intelligibility The
audio bandpass of communication systems can be limited where the objective
is merely to ... |
| July 14 |
HF Mobile Antenna Efficiency The power
radiated by any antenna is equal to the current flowing through its radiation
resistance squared, times ... |
| July 15 |
Radiation Resistance vs. Antenna Resistance The
terms 'radiation resistance' and 'antenna resistance' are sometimes used
interchangeably by ... |
| July 16 |
The Term 'Audio' The term 'audio'
is widely used by both the general public and engineers, but what exactly
does it apply to? Is the sound of your voice ... |
| July 17 |
Information Theory Information Theory
is a branch of statistical communication theory where physical observation
information or the information content of ... |
| July 18 |
Epoxy Resins Epoxy resins are a family
of thermosetting resins widely used in potting, casting and encapsulating
electrical and electronic components ... |
| July 19 |
Crosscorrelation Detectors A crosscorrelation
detector compares a received signal waveform point-by-point with an internally-generated
reference ... |
| July 20 |
Vacuum Tubes above 100 MHz Several
factors degrade the performance of vacuum tubes with increasing frequency.
Interelectrode capacitance ... |
| July 21 |
Parabolic Antenna Feed Illumination An
optimal parabolic transmitting antenna converts cylindrical waves radiating
from an electromagnetic source ... |
| July 22 |
Barkhausen Oscillation There is an
unusual and little-known way to make triode vacuum tubes oscillate at
frequencies far above where they normally ... |
| July 23 |
Steerable Antenna Vertical Directivity HF
dipoles, Yagi's, log-periodic arrays, and other types of antennas are
often made horizontally rotatable to ... |
| July 24 |
Aurora Sputter Fading A particular
type of very-rapid and easily-recognizable VHF signal fading was first
heard in the 1930's where ... |
| July 25 |
Meanings of the Term 'Flux' There
are many specific applications for the term 'flux' in electronics. One
refers to a material that facilitates ... |
| July 26 |
The Doppler Effect Christian Doppler
predicted in 1842 that the frequencies of received waves are dependent
upon any motion of a ... |
| July 27 |
Ferromagnetism Certain materials have
a property called ferromagnetism that gives them relative magnetic permeabilities
exceeding unity ... |
| July 28 |
Buffer Amplifiers The term 'buffer
amplifier' generally refers to an amplifier whose main function is to
provide ... |
| July 29 |
Does Your Antenna Radiate Particles? There
are two correct, but intuitively much different, ways to perceive electromagnetic
radiation ... |
| July 30 |
Vertical HF Antennas Vertical antennas
are used far less than horizontal antennas throughout most of the HF
spectrum, because ... |
| July 31 |
Analog TV Transmissions are Partly SSB A
variety analog broadcast television transmission standards and sub-standards
exist throughout ... |
