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 …
Standing Wave Ratio (SWR) meters are used to measure the standing wave ratio in a communications transmission line. The meter can display how much a transmission line and the load are mismatched (normally a radio antenna). It also determines how effective the impedance is of matching efforts. In CB and ham radio circles, the SWR …
Radio was not invented by any single person, but instead was a culmination of several scientists’ research, each of whom pioneered a different area of electromagnetic radiation and radio waves during the late 1800s and early 1900s. Among these men are well known researchers such as Heinrich Rudolf Hertz, James Clerk Maxwell, David E. Hughes, …
Radio-Frequency Identifier (RFID) technology has become really popular because of the various advantages it comes with. However, such as passports, national identity cards, credit cards etc have become a serious security concern. Two electrical engineering students (Ilan Kirschenbaum and Avishai Wool) from Tel Aviv University wrote a paper titled "How to Build a Low-Cost, …
A high-frequency alternator is an electrical device used for radio communications. It yields high-frequency, periodically alternating current that can go as high as 100,000 Hz for the purpose of producing stable radio waves. The History of High-Frequency Alternators By the first decade of the 20th century, wireless telegraphy was already in place and was no …
A bug detector is a device that is able to locate and/or disable electronic spy equipment such as microphones, cameras, and GPS tracking devices. Law enforcement agencies, military counter-intelligence agencies, criminals, and everyday individuals who are suspicious of being overheard often use bug detectors. Bug detectors are usually small, portable, and have multiple display functions …
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 …
The SMA (SubMiniature Type A) connector is a type of the radio frequency connector developed in the 1960s to make it easier to connect coaxial cables. Using a screw-type design instead of the common ‘push-pull’ system, the SMA connector allows for a quick connection; and can be used in both alternating and direct current applications. …
Four digit security codes protect Kenwood car stereos from theft. If a thief steals a Kenwood car stereo, he/she will not be able to use the stereo until the secret four digit security code is entered. Unfortunately, many legitimate owners are also locked out of their Kenwood car stereos due to these security codes. This …
RFID (Radio Frequency Identification) is a wireless system used to identify tags. These tags may be attached to objects and even embedded under the skin of animals and human beings. Therefore, we can describe RFID as a form of identification tracking that allows retail outlets, airports, zoos, libraries, office buildings, warehouses, and different types of …