RF Transmitter Circuits

  

The transmitting system consists of two tuned circuits such that the one containing the spark-gap is a persistent oscillator; the other, containing the aerial structure, is a free radiator maintained in oscillation by being coupled to the first. The transmitting system consists of two electrically coupled circuits, one of which, containing the air-gap, is a powerful but not persistent oscillator, being provided with a device for quenching the spark so soon as it has imparted sufficient energy to the other circuit containing the aerial structure, this second circuit then independently radiating the train of slightly damped waves at its own period.

For a fixed frequency transmitter one commonly used method is to use a resonant quartz crystal in a Crystal oscillator to fix the frequency. Where the frequency has to be variable, several options can be used.
For VHF transmitters, it is often not possible to operate the oscillator at the final output frequency.
 
In such cases, for reasons including frequency stability, it is better to multiply the frequency of the free running oscillator up to the final, required frequency. The task of many transmitters is to transmit some form of information using a radio signal (carrier wave) which has been modulated to carry the intelligence.
 
A few rare types of transmitter do not carry information: the RF generator in a microwave oven, electrosurgery, and induction heating. RF transmitters that do not carry information are required by law to operate in an ISM band. In many cases the carrier wave is mixed with another electrical signal to impose information upon it. This occurs in Amplitude modulation (AM). Amplitude Modulation: In Amplitude modulation the instantaneous change in the amplitude of the carrier Frequency with respect to the amplitude of the modulating or Base band signal.
 
 

 

 

News

Full-Duplex Chip Will Create a Wireless Bandwidth Bonanza

IEEE Spectrum Full-Duplex Chip Will Create a Wireless Bandwidth Bonanza IEEE Spectrum Our full-duplex receiver can operate at any frequency between 0.8 and 1.4 gigahertz, and the RF self-interference canceler...

Jun 28, 2016

Alaskan Broadcaster Chooses GatesAir DTV and Radio Transmitters

Alaskan Broadcaster Chooses GatesAir DTV and Radio Transmitters Radio World The broadcaster chose a GatesAir Flexiva FAX air-cooled FM radio transmitter for KNLT(FM) in Palmer, Alaska. The station was initially greated...

Jun 27, 2016

Audio-Technica System 10 PRO Wireless Simplifies Assisted Audio for the St. Hilary School in Fairlawn, OH

Audio-Technica System 10 PRO Wireless Simplifies Assisted Audio for the St. Hilary School in Fairlawn, OH Audio Visual News Network The System 10 PRO provides many key features, such as an LED receiver display that shows...

Jun 28, 2016

Heptagon Announces Acquisition of RF Digital Corporation

Heptagon Announces Acquisition of RF Digital Corporation Business Wire (press release) RF Digital (www.rfdigital.com and www.simblee.com) designs and manufactures an extensive line of fully integrated, high quality, high...

Jun 8, 2016

Friday Quiz: RF Power Measurements

Friday Quiz: RF Power Measurements EE Times ... while too much can cause components to overload, burn out, or distort signals. Questions from this week's quiz are based on Principles of Power Measurement: A Primer on...

Jun 24, 2016

Analyst Rating Update on Energous Corporation (WATT)

Analyst Rating Update on Energous Corporation (WATT) Market Digest The wire-free charging solution employs three dimensional (3D) pocketforming via a transmitter that creates a targeted radio frequency ( RF ) pocket in a...

Jun 29, 2016

Testing the RF circuit for IoT success

Testing the RF circuit for IoT success Electronics Weekly Input (receivers) and output stages ( transmitters ) typically utilize an amplifier module to help increase the signal amplitude. With respect to this it makes...

Jun 22, 2016

iHome Selects IDT Technology to Provide Convenience of Wireless Charging in Hotel Rooms

SYS-CON Media (press release) iHome Selects IDT Technology to Provide Convenience of Wireless Charging in Hotel Rooms SYS-CON Media (press release) SAN JOSE, Calif., June 29, 2016 /PRNewswire/ -- Integrated Device...

Jun 29, 2016

Initial ARRL Teachers Institute Session a Success

ARRL Initial ARRL Teachers Institute Session a Success ARRL The class also took part in a hidden transmitter (fox) hunt, and constructed BoeBot® robots. “One teacher programmed her robot to negotiate a maze using RF...

Jun 22, 2016

Coming Soon: ATSC 3.0!

Coming Soon: ATSC 3.0! TV Technology ATSC 3.0 test transmissions are on the air now from Sinclair's experimental single frequency network (SFN) on Channel 43 in Baltimore and Washington, D.C. Over-the-air ATSC 3.0 was...

Jun 22, 2016