- How is integrated model of crime developed. What are it’s features, and how is it expressed?
- In which ways were the political Era and Community Era of law enforcement within the United States both different and similar in their characteristics?
Antenna is an electronic device mostly known as transducer that is designed to receive and transmit electromagnetic waves and can be very effective in the telecommunication systems. It was the most neglected section of all the personal communication systems. But with the rapid evolution of the technology, communication is expected to be transmitted and received quickly and with fewer errors whether it is through wireless networks or otherwise, thus antennas can solve this problem. Actually it is not the Antennas which are smart but the smart system that makes it work are smart. Smart antennas consists of many other antennas which when combine together would produce or receive signals faster and more efficient. Normally this set of antennas is called MIMO which means multiple inputs -multiple outputs. . Beamforming is a technique where signals are processed and send to the direction of the receiver or vice-versa. The signal is either a fix pattern or adaptive pattern that is modified to make maximum usage of signal. Background Smart Antennas can be referred as a new technology which is used with the mobile communication, but in fact the first Smart Antennas were introduced to use by the government in the military application in 1960s. The transmission of the signal used directed beams to avoid environmental interferences such as noise and at the same time hiding transmitted data from enemies. During those days the antennas structure was very large and it was time-consuming to calculate the exact transmission rate and correctness of the signal. In 1987, the concept of wireless communication has been invented by Marconi and since then there has been an extensive and continuing increase in the use of mobile communication. Newer technologies and approach were explored and deployed and when the latest one that is the Space Division Multiple Access (SDMA) has been emerged it brings a promising future to the wireless communication. SDMA is based on the use of Smart Antennas and researchers have worked on this technology to apply it on personal communication. Types of Smart Antennas There are two main types of Smart Antennas Switched beam is the simplest structure of Smart Antennas; it forms fixed multiples beams to serve users in a predefined way. The signal gives its best performance by switching from one beam to another when the user of the mobile moves through their cell. The table below shows how this approach works:>