| Date |
Fact of the Day Topic |
| April 1 |
Null Hypothesis In hypothesis testing, a
null hypothesis is the hypothesis that is being tested. For example ... |
| April 2 |
Speech Frequency Components Human speech
frequency components change rapidly with time. They also tend to have
... |
| April 3 |
Sound-Induced Hearing Loss Radio amateurs
and others who listen to high-amplitude signals and noise for long time
periods risk ... |
| April 4 |
Human Differential Sound Intensity Sensitivity How
much does the RF output of a CW or SSB transmitter have to be increased
for a loudness change ... |
| April 5 |
Compression and Expansion Only the peaks
of an RF envelope can be heard when the peak-to-peak amplitude of an
SSB signal is ... |
| April 6 |
Dimension of a Space The number of coordinates
needed to specify a point in a space is the dimension of the space. For
example ... |
| April 7 |
Geographic vs. Magnetic Poles The magnetic
pole that is near earth's geographic north-pole is, of course, a south-pole,
because ... |
| April 8 |
Earth Magnetic Field Decline The earth's
geomagnetic magnetic field strength was first measured in the 1830's.
Since that time ... |
| April 9 |
Earth Magnetic Field Distribution Earth's
geomagnetic field is rather weak at and above the surface of the earth,
but ... |
| April 10 |
Earth Magnetic Reversal Frequency Studies
of magnetization orientations in magnetic minerals in the earth have
revealed ... |
| April 11 |
Earth Magnetic Reversal Speed Some self-proclaimed
experts have written books and magazine articles, and have been on radio
talk shows ... |
| April 12 |
Never Used Linux? Many computer users say
they have never used Linux when in fact they use it almost every day
... |
| April 13 |
Laser History Most people involved with
electronics know the word laser is an acronym for Light Amplification
by ... |
| April 14 |
Multiple Coax Cable Feedlines Most modern
communications radios have 50-ohm unbalanced antenna connections, but
... |
| April 15 |
50 Hz vs. 60 Hz Power Transformers More
iron and/or more turns of wire are required to have the same transformer
winding ... |
| April 16 |
UPS RFI That high noise level you have
been blaming on the power company may be coming from under your desk
... |
| April 17 |
Two Types of Ferrite There are two basic
types of ferrite, hard ferrite and soft ferrite. However, those designations
can be misleading, because ... |
| April 18 |
Cleanup Windows Clutter Windows clutters
computer hard disks with many unnecessary files. For example, detailed
... |
| April 19 |
Ferrite Inductor DC Direct current can
have large effects on the inductance of chokes, filters and transformers
wound on ferrite cores ... |
| April 20 |
Horizontal Antennas near Earth The feed-impedance
of a horizontal antenna cycles above and below its free-space value as
... |
| April 21 |
Kennelly-Heaviside Layer (Ionosphere) The
existence of the ionosphere was independently surmised by Arthur E. Kennelly
in ... |
| April 22 |
Smith Chart A Smith Chart, also known as
a Smith Diagram, is special type of chart that was developed to enable
easy graphic solution of ... |
| April 23 |
A Long Balanced Feedline is a Balun A current
balun will make the radiation pattern of most center-fed dipole antennas
more symmetrical ... |
| April 24 |
Multiple Dipole Multiband Antennas Several
halfwave dipoles that are resonant at different frequencies can be center-fed
from a common ... |
| April 25 |
Air Breakdown Voltage Air is a good insulator
at low values of electric field strength, because electrons attach to
atoms of oxygen faster... |
| April 26 |
Large Horizontal Loop Antennas Large horizontal
loops are popular HF antennas for good reasons. They tend to have generally
similar ... |
| April 27 |
New Lightning Theories Lighting has been
generally considered in the past to be an extremely large electric spark.
However, one of its most puzzling ... |
| April 28 |
RF Balun Construction Both 1:1 and impedance
transforming RF baluns of various designs are relatively easy to construct
by ... |
| April 29 |
Non-Contaminating Vinyl (NCV) Chemical
plasticizers in coax cable jacket material, such as PVC, can leach or
migrate through coax cable shields ... |
| April 30 |
Underground Power Cable Faults Underground
power distribution is now common in most upscale communities. There are
many advantages ... |
