A transponder, transceiver, and scanning antenna are the three main parts of every RF identification system. An RFID interrogator or reader is a transceiver and scanning antenna in one convenient device. RFID readers can either be permanently installed or portable.
The Radio-Frequency ID reader is a portable or fixed device that connects to a network and reads tags. It sends messages to the tag via radio waves, which causes the tag to become active. After getting activated, the tag will return a wave that will get picked up by the antenna and decoded.
The RF identification tag itself contains the transponder. RFID tag read ranges change depending on a number of parameters. They include the reader and tag design, RF identification frequency, and environmental and peer interference. More powerful tags are readable from even further away.
How To Select An RFID Antenna?
The Radio-frequency ID antenna receives energy from the RF identification reader. And broadcasts it as radio waves to any RFID tags within range. Antennas are the hands and feet of an RFID system. They are responsible for sending and receiving data between RFID tags and readers. Most RFID antennas have a standard, uniform design. Differences emerge from their unique anatomical characteristics. There are many factors to think about when selecting an antenna. They include polarization, opening beamwidth/angle, amplification, and frequency range.
· Frequency Range
Each country has its own rules about what sort of UHF/RFID frequencies are legal to use. In general, UHF RF identification antennas operate in one of three frequency bands:
- EU/ETSI 865–868 Megahertz
- US/FCC 902–928 Megahertz
- Other global bands 860–960 Megahertz.
Pick a radio frequency identification antenna with a frequency range appropriate for its intended use area.
· Amplification & Opening Angle
In physics, the relationship between opening angle and gain, or beamwidth, is particularly strong. Since a narrower radio wave has a higher gain, it can cover less ground but travel farther in a single beam. In conclusion, the amplitude of a wave affects its overall width. Higher amplification results in a more concentrated wave.
Different intensities of a flashlight beam can be used to illustrate this concept. In this case, the answer will determine which antenna should get chosen. An antenna with moderate amplification power and a larger beam is ideal if there are multiple tags in close vicinity.
· Polarization
The polarization of most RFID Ultra high-frequency antennas is either linear or circular. Therefore, antennas with linear polarization only radiate radio frequency energy in a single direction. It can be in either a horizontal or vertically direction. Antennas with a circular polarization radiate wave in a spherical pattern, either counterclockwise or clockwise.
We make a distinction here between LHCP and RHCP. It’s crucial to determine whether or not an array of antennas is RHCP or LHCP if they’re all pointed in the same direction. The overlapping of circular antennas with the same polarization is possible by deploying antennas with counter-rotating circular polarizations. A larger, more productive reading area becomes establishable.
Which RFID Antenna Is The Right One? Circular Polarization Or Linear Polarization:
A lot of rides on whether or not an RFID system uses a circularly polarized antenna as opposed to a linear polarization antenna.
In the case of EM waves, the linear polarization effect occurs when the waves get transmitted in a single direction (vertical or horizontal). When all RF identification tags are vertically aligned, and at the same height, linearly polarized antennas perform the best. A linear antenna’s concentrated transmission allows it to outperform a circular antenna of equal amplification in terms of reading range.
When the orientation and location of an RFID tag become unpredictable, omnidirectional antennas are the best option. Their waves have been likened to a corkscrew turning in 2 dimensions. Because of the two-dimensional power loss inherent with omnidirectional antennas, their reading range is inferior to that of linear antennas.
Understanding how antennas function and how RF identification tags get oriented with respect to the antenna is crucial when deciding on the type of antennas that will get used in an RF Identification system.
Different Types of RFID antennas
1. Small & large RFID antennas
Antennas range in size from those designed for mobile phones to those designed for television sets. A size disparity is an excellent indicator of possible reading distance. For a given read range, a larger antenna will provide a greater effective distance. The antenna you choose may also get affected by where you decide to install it. Large antennas may not be suitable for certain installation sites due to space constraints or aesthetic preferences.
2. Internal & external RFID antennas
Aspects of the system could be water and dust-resistant because RF Identification can be used in virtually any setting. All electronic components get verified as dust and waterproof to at least one of the standards set out by the American IEC 60529 and the British EN 60529. Working temperature is considered while deciding whether or not to use the antenna outdoors. In order to function at their best, the antennas can only get exposed to certain temperatures. The antenna’s performance degrades or stops altogether when moved outside this range.
3. Integrated & non-integrated RFID antennas
Antennas are purchasable independently of the RFID reader or packaged together in a single device. The elimination of the need for wires allows for a more compact and portable system to get constructed when integrated devices are used. Because such a solution is typically smaller, simpler to operate, and more aesthetically pleasing than two difficult portable drives, it may be the best option for distribution and retail settings. However, external antennas offer a broader range of design and application options.
How Does RFID Antena Work?
In the family of technologies known as AIDC, RFID is one member. Automatic identification and data capture (AIDC) techniques can be used to recognize things automatically, gather information about them, and input that data into computers with minimal human involvement. RFID systems do this by sending a signal across the air using radio waves. There are three main parts to any RFID system: the tag itself, the reader, and the antenna. Data is transmitted from the RFID tag’s IC through its antenna to the reader. The reader is also known as an interrogator. After receiving the radio waves, the reader transforms them into a more usable format. Data from tags get transmitted via the communication menu system to a host machine, where it gets entered into a database and prepared for further analysis.
Challenges
There are two basic problems with RFID:
· Reader Collision
When two or more RFID readers are in close proximity to one another, a phenomenon known as reader collision can occur. To avoid this, an anti-collision strategy can be implemented to have RFID tags alternate between broadcasting to different readers.
· Tag Collision
When a large number of RFID tags try to send information to a reader at once, this is known as a “tag collision.” This is avoidable by using a reader that collects tag data sequentially.
