This is because RFID tags are going to use as much electric field as magnetic field to communicate their information, depending on the frequency they are using. When a reader emits radiofrequency signals , it causes variations in the electric and magnetic fields. This coupling is known as inductive coupling. Inductive coupling is the communication process used by LF and HF passive tags.
This is called backscatter passive communication or backscatter modulation. The term «energy» refers to the radio frequency signal strength. The basic unit of energy is the watt. However, in the RF world, we talk about power in terms of milliwatts, shortened to mW.
Depending on the applications and benefits sought, radio frequency energy can be provided through different RF systems: generators, industrial oven, or radio frequency tunnels. Radio frequency is a form of electromagnetic radiation, which may suggest that it is dangerous. But as it is non-ionizing radiation, its effect does not last over time.
The reliability of the radio frequency generators offered by SAIREM is recognized and appreciated equally as standalone or integrated units by many OEMs and research laboratories worldwide. Their modern design allows them to be easily integrated and used in a wide variety of environments. Our radio frequency generators are designed to operate independently or remotely, with a minimal footprint and good signal stability.
They can deliver anything from a few hundred watts up to hundreds of kW with significantly reduced power losses. Industrial radio frequency generators Mainly used in industrial thermal processes, radio frequency generators are useful for many different applications, such as heating or drying industrial or food products.
The capabilities of the test instruments available have developed considerably in recent years, but the basic concepts remain the same.
Whatever the type of oscillator used, stability, control, accuracy and also phase noise are key issues. For many of todays test instrumentation requirements, the use of frequency synthesizers means that the stability, control and accuracy are very good. However the phase noise can be an issue in some applications.
In order to understand the operation of a generic microwave or RF signal generator it is useful to understand what is included in terms of a basic block diagram.
Microwave and RF signal generators are able to offer a large variety of functions and facilities these days. These include some that are detailed below:. Microwave and RF signal generators are widely used in test laboratories dealing with radio equipment of any sort - these test instruments can be used for everything from cellular to communications equipment, broadcast transmitters and receivers, wireless products including Bluetooth, Wi-Fi and many more standards.
With many more items using RF and microwave signals, the use of RF signal generators will only increase. There is a large variety of these test instruments available from a variety of different manufacturers and suppliers, and the different RF signal generators vary considerably in the specifications and capabilities they offer. In view of the costs of these test instruments, it is possible to buy them new or as second user test equipment.
A typical RF signal generator Types of RF signal generator It is possible to design radio frequency signal generators in a variety of ways. It can be said that there are two forms of signal generator that can be used: Free running RF signal generators: These RF generators are rarely used these days as their frequency tends to drift.
Sometimes low end simple signal generators utilised one or two transistors and had a very basic level of performance and their cost was affordable for many experimenters. These very basic RF signal generators are now rarely seen these days. However high end free running RF generators have been made and they have the advantage that the signal produced is very clean and does not have the level of phase noise either side of the main signal that is present on some other radio frequency signal generators.
Some signal generators used a form of frequency locked loop to provide a means of adding some frequency stability while still retaining the very low levels of phase noise. Again, these are not common these days because the performance of RF signal generators using frequency synthesizer technology has considerably improved.
Synthesized radio frequency signal generators: Virtually all radio frequency signal generators used today employ frequency synthesizer technology. Using this technique enables frequencies to be entered directly from a keypad, or via remote control and it also enables the output signal to be determined very accurately.
The accuracy being dependent upon either an internal reference oscillator that can have a very high degree of accuracy, or the signal can be locked to an external frequency reference which can be exceedingly accurate.
There are two main techniques that are used within synthesized RF signal generators: Phase locked loop synthesizer: Phase locked loop synthesizers are used within most RF signal generators as they enable signals to be generated over a wide range of frequencies with a relatively low level of spurious signals.
Phase locked loop synthesizer technology is well developed and enables high performance RF signal generators to be produced using them. They enable very fine frequency increments to be achieved relatively easily.
However the maximum limit of a DDS is normally much lower than the top frequencies required for the signal generator, so they are used in conjunction with phase locked loops to give the required frequency range.
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