dBm is the standard unit of measure for levels of power based on a one milliwatt (mW) reference signal. The dBm measurement is very similar to dB (decibel); however, dB is a relative measure of the power of an input signal while dBm is always an absolute value based on a single milliwatt. If there …
A frequency changer makes it possible to change electricity moving at one frequency to another frequency. However, in order to fully understand what a frequency changer does, it is helpful to understand the frequency of electricity. The Frequency of Electricity Electricity doesn't move at one specific speed. In fact, it can move at many speeds. …
MURS, or the Multi-Use Radio Service, is a public radio service created by the FCC in the Fall of 2000 that can be accessed by any individual for personal or business-related purpose. MURS was created for the general public to use without acquiring a license to broadcast, but requires that users remain within the frequencies …
A spot beam is a beam of radio signals that is directed towards a specific area on the Earth’s surface. Spot beams are the opposite of broad beams, which are beams that are directed towards a large area of the Earth’s surface. While broad beams are used for general telecommunication and surveillance, spot beams are …
Portable radios are limited in the power at which they can transmit, usually somewhere between .5 watts and 5 watts. A very rough rule of thumb is that one watt equals one mile of range over flat and open terrain. Buildings and mountains will, of course, greatly modify effective range. When two radios communicate directly …
An EMF meter detects and measures an electromagnetic field. There are many types of EMF meters and they have many uses, including ghost hunting. Most EMF meters are “AC EMF meters” and can only detect the rate of change in an oscillating magnetic field. However, commercial grade EMF meters that can detect specific electromagnetic frequency …
In order to understand how sunspots effect radio reception, you need to understand that the light waves and radio waves that the sun emits are both categorized as electromagnetic (EM) radiation. While light waves are visible to the human eye, they are still electromagnetic waves that oscillate. There are many electro magnetic waves, some oscillate …
A circulator is a box-shaped ferrite device that has three or four ports and allows energy from one port to transfer to the next port in line. Circulators are usually used with radio signals but can also be used with microwaves, light, and other electromagnetic waves. This means that a radio signal that is being …
A TRIAC is used in AC power control applications in order to switch high voltages over both parts of the AC waveform. As a result, TRIAC circuits are used in a number of applications that require power switching. The TRIAC was developed after the thyristor, which controls AC current over one half of the cycle. …
Basic diodes are constructed from two semiconductor materials, germanium or silicon, to create a basic PN-junction. When two single diodes are connected to each other back-to-back, two PN-junctions that are connected in series are created. They share a common N or P terminal, which forms the basis of a BJT or Bipolar Junction Transistor. The …