Radio Frequency (RF) Signal Generator – Features & Applications

A radio frequency (RF) signal generator is used in generating high frequency signals at a specific frequency for testing laboratories. The output frequency may range for example from about 100 kHz to around 40 GHz.  A typical RG generator consists of: RF oscillator, amplifier, output level meter and a calibrated attenuator.

Components of RF Generator

RF Oscillator

This oscillator includes a continuous frequency control and a frequency range switch, to set the output to any desired frequency.

The oscillator circuit that is used in RF generator is normally either a Colpitts or Hartley oscillator.

Amplifier

The amplifier has an output amplitude control. This allows the voltage applied to the attenuator to be set to a calibration point on the output level meter.

Output Level Meter

The output level must always be reset to the calibration point each time the frequency is changed. This is done at the output level meter.

Calibrated Attenuator

The calibrated attenuator displays the correct voltage level (set to a calibration point on the output level meter) from the amplifier.

Common Features RF Generators

Many RF generators have features for amplitude modulation (AM) and frequency modulation (FM) of the output. Switches are provided on the front panel to allow the user to select no modulation in addition to internal or external AM or FM modulation.

Every section of the RF generator is shielded by enclosing it in a metal box. The whole system is then completely shielded. This shielding is necessary to prevent:

• RF interference between the components.
• Emission of RF energy from any point with the exception of output terminals. In fact, even the power line is decoupled by means of RF chokes and capacitors to prevent RF emission from it.

Applications of RF Generators

RF signal generators are commonly used in radar and communication, research and development labs, education and training, electromagnetic interference (EMI) testing and material testing. Their major uses include:

• Used to perform tests on radio transmitters and receivers.
• Used to test the amplitude and frequency response of RF amplifiers during the design phase.

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