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

New Transmitters From BSI help CBS, Turner Overcome RF Challenges at PGA Tourney

Sports Video Group New Transmitters From BSI help CBS, Turner Overcome RF Challenges at PGA Tourney Sports Video Group Broadcast Sports International (BSI) was on hand with three full trucks in the production...

Aug 2, 2016

Verizon Updates 5G Spec, Could Launch Ahead of 3GPP

Verizon Updates 5G Spec, Could Launch Ahead of 3GPP Light Reading "We recently rented an apartment, and we put a transmitter down the road a ways," Koeppe noted. Signals ... She stated that RF , ASIC and test...

Aug 25, 2016

GatesAir Completes Phase 2 Rollout in Kuwait

GatesAir Completes Phase 2 Rollout in Kuwait TV News Check State broadcaster, Kuwait Television, selected GatesAir for both phases due to its ability to provide turnkey equipment and services, including the design, supply...

Aug 24, 2016

Is Pokémon GO a threat to drones?

DirectionsMag.com Is Pokémon GO a threat to drones? DirectionsMag.com ... taken root but developers have evolved from application spoofing to creating more complex RF signal attacks using techniques similar to the...

Aug 24, 2016

A Solid Wall of RF

Radio magazine A Solid Wall of RF Radio magazine One of those rare things was a small FM transmitter with digital readout. You might remember these little transmitters . Before streaming was cool, one could take a...

Aug 19, 2016

Sennheiser and Neumann's IBC content production offerings

Sennheiser and Neumann's IBC content production offerings AV Magazine “A lot of expertise in RF wireless technology went into the development of this series, which is why it is such an easy-to-use tool for...

Aug 24, 2016

"Interscatter" Tech Converts Bluetooth For WiFi-Connected Implants

Med Device Online (press release) "Interscatter" Tech Converts Bluetooth For WiFi-Connected Implants Med Device Online (press release) The UW team previously described the technique of...

Aug 23, 2016

Avlex and MIPRO Introduce 7 Series Rechargeable Transmitters

TV Technology Avlex and MIPRO Introduce 7 Series Rechargeable Transmitters TV Technology Like the ACT-70HC Handheld Microphone, the new ACT-70TC Bodypack Transmitter delivers state-of-the-art audio performance....

Aug 19, 2016

RFID, AIDC, and IoT News: Intel Demonstrates New Mote that Can Track Parcel Handling History

Supply Chain Digest RFID, AIDC, and IoT News: Intel Demonstrates New Mote that Can Track Parcel Handling History Supply Chain Digest In 2013, SCDigest reported on new technology developed by research firm Cambridge...

Aug 22, 2016

GatesAir Brings Latest Wireless Over-The-Air Content Delivery Solutions for FM Radio to IBC2016

GatesAir Brings Latest Wireless Over-The-Air Content Delivery Solutions for FM Radio to IBC2016 Radio magazine The European debut of the GatesAir Flexiva™ LX solid-state FM radio transmitter sets the latest standard for...

Aug 22, 2016