Radio Frequencies

Radio frequency or RF is a frequency or rate of oscillation in the range of 3 Hz to 300 Ghz. This range relates to the frequency of alternating current electrical signals to create and detect radio waves. As this range is beyond the vibration rate that many mechanical systems respond to, RF refers to oscillations in electrical circuits. When the current is input to an antenna, an electromagnetic field is generated that is suitable for wireless broadcasting and/or communications. These frequencies cover the electromagnetic radiation spectrum ranging from nine kilohertz, the lowest allocated wireless communications frequency to thousands of gigahertz. When an RF current is given to an antenna, an electromagnetic field is created that propagates through space.

Properties of Radio Frequency electrical signals

• the ease with which air can be ionized to create a conductive path across air
• electromagnetic force that drives the RF current to the surface of conductors known as skin effect
• ability to appear to flow through paths containing insulating material similar to the dielectric insulator of the capacitor

Radio spectrum
Extremely low frequency is 3 to 30 Hz
Super low frequency is 30 to 300 Hz
Ultra low frequency is 300 Hz to 3 Khz
Very low frequency is 3 Khz to 30 Khz
Low frequency is 30 Khz to 300 Khz
Medium frequency is 300 Khz to 3 Mhz
High frequency is 3 Mhz to 30 Mhz
Very high frequency is 30 Mhz to 300 Mhz
Ultra high frequency is 300 Mhz to 3 Ghz
Super high frequency is 3 Ghz to 30 Ghz
Extremely high frequency is 30 Ghz to 300 Ghz

Radio frequency encoding
These techniques physically encapsulate an RF encodable microchip with the synthesis resin. The RF transponder can be scanned post-synthesis to identify the concerned product. RF encoding avoids the need to cosynthesize surrogate analytes and permit the large scale synthesis of compounds as each microcapsule can hold tens milligrams of synthesis beads.

Radio frequency identification
This is an automatic identification method. RFID tags or transponders are used for storing and remotely retrieving data. An RFID tag is an object that can be applied in a product, animal or person with the aim of identification using radiowaves. Some tags can be read beyond the line of sight of the reader. These tags consist of two parts. One is an integrated circuit for storing and processing information, modulating and demodulating signal and for other specialized functions. The second is an antenna used for receiving and transmitting the signal. Chipless RFID has discrete identification of tags in the absence of an integrated circuit, so that tags are printed directly on assets at lower costs than traditional tags.

RFID tags types
The various tag types are as follows:

• Passive : There is no internal power supply. The practical read distances range from 10 cm to a few meters, depending on the selected radio frequency and antenna design/size
• Active : There is an internal power source. The range is of hundreds of meters and the battery life is of about 10 years
• Semi-passive : They have their own power source. The battery powers the microchip and cannot broadcast any signal

Use of RFID technology

• RFID chips for animals are very small devices injected through a syringe under the skin
• Real-time inventory tracking allows companies to control supply
• RFID systems are used in some hospitals to track a patient's location, doctors and nurses
• Traffic monitoring system uses roadside readers to collect signals from transponders