How Radio Frequencies Work With Generators

Radio frequency signal generators, colloquially known as RF signal generators, are a test equipment of particularly great use when it comes to RF microwave design and test applications. This type of equipment comes in many forms and is used in a wide variety of capabilities of facilities.

It is essential to understand how RF signal generators perform and operate in order to make use of this technology efficiently.

Types of Radio Frequency Signal Generator

As mentioned, RF signal generators come in many forms. And with the innovations developed in electronic circuitry over the years, the designs and techniques have progressed rapidly.

Generally, two forms of signal generators are used:

1. Free Running RF Signal Generators: Although its use and commonality have reduced over the years, free running RF signal generators are still preferred by some due to its clean generation of signals and the minimum phase noise it produces either side of the main signal that, which is the tendency for other RF signal generators.

To retain the lowest level of phase noise, some signal generators use a locked loop form of frequency. This also makes the frequency more stable. However, with the rampant development of new technology in radio frequency, the use of this type of RF signal generator has become rare.

2. Synthesized Radio Frequency Signal Generators: It’s safe to say that at this point, nearly all RF signal generators being used employ frequency synthesizers. This is due to the fact that this method allows frequencies to enter directly from a keypad or through a remote device, which makes a very accurate reading of output signals. The accuracy depends either on the signal locked to an external frequency reference, or an internal reference oscillator, both having the capability to produce extremely accurate results.

Synthesized radio frequency signal generators are used for two main methods: direct digital synthesizer (DDS) and phase locked loop synthesizer.

Functions of Radio Frequency Signal Generator

RF signal generators perform in many different functions these days. Some of the most common are outlined below:

• Frequency Range – The range of the frequency the RF signal generator can handle is obviously hugely important. It should have the capacity to cover the frequencies needed to be generated. For instance, when testing a mobile phone’s receiver, it is critical to find out not only the operating frequency. Other frequencies should be tested too (i.e image rejection, etc) to determine issues.
• Output Range – The RF signal generator’s output level is manipulated in order to achieve the highest level of accuracy. Within the generator itself, the output is controlled at a constant level, which is then passed through a variable attenuator, which is typically switched to produce accurate test results. The level may be limited at the top end by the RF signal generator’s final amplifier.
• Modulation – The RF signal generator’s output signal can be modulated by either an external source or using its inbuilt oscillator. As formats used in modulation have evolved through the years, the RF signal generator’s capabilities have improved as well, with some capable of modulation formats such QAM, QPSK, and a smattering of others. Signal generators that have the capability to support complex forms of modulation are often called vector signal generators.
• Control – You can control RF signal generators in so many ways these days. Most of them still have the traditional front panel controls, but remote controls have been also made available. An example can be seen in lab bench test utilities where GPIB fitted is standard, but other options such as Ethernet, RS-232, and LXI Rack technologies are also commonly used. You will likely find more affordable varieties such as PXI and PXI express, but you won’t miss VXI either.
• Sweep – On some radio frequency signal generators, it is required to sweep the signal over a range, while on other generators, this isn’t exactly a necessity.

Radio frequency signal generators are an important type of electronic test technology common in test labs or radio frequency design equipment. These signal generators are necessary when it comes to instances in which radio frequency needs to be provided to a gadget or circuit that is currently being tested or developed.

In conclusion, radio signal generators are an important piece of technology for radio frequency testing and development.