The Ultra High Frequency (UHF) band which uses the Radio Frequency Identification (RFID) system has it gained popularity in many applications, as it provides longer readable range and fast reading speed [1]. The commercial use of the UHF RFID system in logistics, and supply chain management has become very pop-ular, which has made compact handheld reader units become more and more important RFID technology uses the short-range wireless communications and information in the device (tag) can be read by using the radio frequency. The reader antenna is one of the important components in the RFID system. Circularly polarized microstrip antennas (CPMAs) can reduce the loss caused by the multipath effects between the reader and the tag antenna. Due to the merits of high data transfer rate and broad readable range, passive RFID systems at the UHF band are preferred in many applications.
The system operates at the bands of 840–955 MHz in Asia-Pacific region, 902–928 MHz in America, and 865–867 MHz in Europe. The main contemplation for the Circularly Polarized (CP) microstrip antenna design of handheld/movable RFID reader applications is complete compact size of the antenna. The small size of the CPMA can be achieved at the cost of limited gain, narrow 3-dB AR bandwidth and impedance bandwidth.
Compact circularly polarized microstrip antennas (CPMAs) are mostly used in handheld portable devices and in compact portable communication systems. Circular polarization is the most common polarization types used in modern wireless communication systems. For overall size fof the antenna several applications want compact circularly polarized slotted microstrip antenna, such as for mobile wireless, radio-frequency identification (RFID) readers, and...
... middle of paper ...
...ion, Vol. 29. pp. 949-955, 1983
[6] H. Iwasaki, “A Circularly Polarized Small Size Microstrip Antenna With Cross slot,” IEEE Transactions on Antennas and propagation. Vol. 44. No. 10. pp. 1399-1401, 1996.
[7] K. L. Wong and Y. F. Lin, “Circularly Polarized Microstrip Antenna with a Tuning Stub,” Electron. Lett., Vol.34, No. 9,pp. 831-832, 1998
[8] H. M. Chen and K. L. Wong, “On the Circular Polarization Operation of Annular-ring Microstrip Antennas,” IEEE Transactions on Antennas and propagation, Vol. 47, pp. 1289-1292, 1999.
[9] W. S. Chen, C. K. Wu and K. L. Wong, “Novel Compact Circularly Polarized Square Microstrip Antenna,” IEEE Transactions on Antennas and propagation, Vol. 47. pp. 340-342, 2001.
[10] J. S. Row and C. Y. Ai, “Compact Design of Single Feed Circularly Polarized Microstrip Antenna,” Electronics letters, Vol. 40, No. 18, pp. 1093-1094, 2004.
was first conceived by Michael Faraday in the year 1832 in his Backerian Lecture to
"The Future of the Wireless Art," Wireless Telegraphy and Telephony, 1908, pg. 67–71, Nikola Tesla
In 1937, Canadian inventor Donald L. Hings created literally a big thing in size and value wise. He called it a two-way field radio but it is now known as the Walkie Talkie. The Walkie Talkie when first created was the size of a back pack and i...
White, Thomas. "The Development of Radio Networks." Early Radio History. Early Radio History, 2010. Web. 20 Sep 2010.
There has been significant technological advancements over the past few decades that have revolutionized the way we live and conduct business. Radio Frequency Identification, or RFID is an example of an electronic data interchange network that has helped shape the global world in which we live. The applications of RFID technology has impacted the military, health industries, supply chain management, logistics and agriculture. There is a vast array by which RFID technology is used around us on a daily basis without us even realizing it.
The Association for Automatic Identification and Mobility (2012) defines RFID as a universal term that is used to describe a system that transmits the identity of an object or person wirelessly, using radio waves. The function of an RFID system is to enable data to be transmitted by a portable device, called a tag, which is read by an RFID reader and processed according to the needs of a particular application (Association for Automatic Identification and Mobility, 2012). RFID tags are a small object that can be implanted or attached into products (clothing, shoes ect.), humans, or animals that enable storing and retrieving data possible. With no physical contact required, this type of data can be collected and read through clothing, the human body, and non-metallic materials. In recent years, RFID tags have been used in identifying animals for health or nonhealth reason...
Discuss the evolution of radio from the 1940’S to the present, reflecting on significant changes.
- Crowther, J. A. Men of Science: The Life and Discoveries of Michael Faraday. New
The RFID tag itself is about the size of a pinhead or grain of sand. The tag includes an antenna and a chip that contains an electronic product code. Industry professionals expect the RFID tag to eventually replace the barcode as identification system of choice. The electronic product code stores much more information than a regular bar code that is capable of storing information like when and where the product was made, where the components come from, and when they might perish. Unlike barcodes, which needs a line-of-sight to be read, RFIDs do not need a line-of-sight. There are two types of RFID tags call active and passive. An active tag uses its own battery power to contact the reader. It works greater distance than passive tags, but has a drawback because of the larger size. A passive tag does not require a battery, but it derives its power from the electromagnetic field created by the signal from the RFID reader. This generates enough power for the tag to respond to the reader with its information, while the range is smaller than active tags, having no battery make the tags useful life almost unlimited and the size much smaller than active tags. In any event, the key feature of the technology is the ability for an RFID-tagged object to be tracked instantly from anywhere in the world, provided that the reader is in range.
MTC ONLINE, " Reports of Current Experimentation with Microwave and EM Weapons," <http://www.heart7.net/mcf/1.html> (10 August 2003)
The level of RF a person receives is related to many factors, not only the placement of the antenna. Factors that can increase the level of RF are the number of “cells”, the distance to the “base station”, or the obstacles between the caller and the station. The number of cell zones depends on the user population. Heavily populated areas have more cells allowing for more telecommunication traffic. Being close to a cell site lowers the power needed to sustain a call, hence reduces the exposure to RF.
RFID has taken strides from being a far off solution to becoming a mainstream application that helps speed the handling of manufactured goods and materials. RFID is an identification and tracking tool for a product using radio waves. It uses a microchip and a printed antenna that can be then packaged in several different forms such as a label or embedded between layers of a carton. These labels are then used to identify the manufacturer, product category and the RFID enables this identification from a distance and unlike earlier bar-code technology, it does so without requiring a line of sight. (Finkelzeller)
It is quite obvious of how to measure linearly polarized components of the wave. But as was already mentioned, polarized light can be decomposed into superposition of two circularly polarized components of opposite handedness: circularly right- and left-polarized. How can we measure this two components? While Ex, Ey are components in the standard Cartesian basis (x y), Ea and Eb are components in Cartesian basis rotated by 45° (a b), the Er and El are components in the circular basis defined so that
As mentioned above the RFID system has three major components; the tag, the reader, and the back-end system. There are two types of RFID tags: active and passive. Active tags have a battery power source and therefore have a finite life. These tags are writable and readable. Passive tags on the other hand, are fairly simple. When they are in the proximity of a RFID reader, the tag begins to transmit data that it has stored in its memory. The radio transmission from the reader provides the power needed for the tag to function. (Paraschiv pg 10) The reader is composed of a frequency module, a control unit, and a control unit which helps it communicate with the tag through radio transmission. Readers can take various forms from mobile or portable d...