How Do Microwave Wireless Antennas Work?



How Do Microwave Wireless Antennas Work?


How Wireless Antennas Work

In the middle of the radio transmission/reception process sit two antennas, one at the building from which the signal is transmitted and one at the building receiving the signal. Of course, it is possible to have one central location and several remote locations connected to the network. For discussion's sake, though, let's think of the communication process as a straight line, from one antenna to the other.

In order to transmit the modulated radio signal, an electrical current passes through the antenna, inducing a magnetic field, which oscillates at the given frequency. The variations in the current create slight variations in the radio frequency. These radio waves radiate outward from the antenna in a "beam" according to the antenna's design.

On the other end, when the radio is in receive mode, the antenna is passive. The electromagnetic radiation from the originating antenna passes across the receiving antenna. This creates a magnetic field, which, in turn, induces an electrical current through the antenna. The current passes through the radio receiver and is demodulated back into an electrical signal with the same form as the original electrical signal from the first network bridge/router. This electrical signal passes to the bridge/router portion of the receiving unit as a normal data signal.

As if by magic, a data signal is transferred from one network bridge/router to another without the necessity or expense of an interconnecting wire. More information about the various antennas used in wireless networking is presented in the next section.



What is the Difference Between an Omni Directional and a Directional Sector Antenna?



Different Types of Wireless Antennas

Because the radio equipment used in wireless networkingmust by law be very low-powered to minimize interference with other devices, the antennas required are much more focused than those used in radio or television applications. The amount of focus they use in transmitting a signal, and their corresponding ability to "pick out" specific radio signals is called
gain. The gain is measured in decibels, abbreviated dB.


Sector Wireless Antennas

There are two major categories of antennas: directional and omni-directional. Directional antennas focus their energy in tight, narrow beams. When receiving signals, directional antennas do not "see" any signals coming from outside the "beam" on which they are focused. This eliminates a great deal of potential interference from other radio sources and contributes to the
ability of multiple wireless communications systems to coexist with a minimum of interference.


Omni Directional Wireless Antennas

Omni-directional antennas transmit their energy in a full circle. Spreading the radio signal over such a large area reduces the energy in the signal. This severely restricts the distance the signal can be transmitted and received effectively. Therefore, transmissions via an omni-directional antenna do not travel as far before being degraded as do those from directional antennas. (However, amplifiers are available for both types of antennas to lengthen the transmit distance.)

Hotware-Zigwire solution devices have built in amplifiers tunedfor maximum through-put , examples below These characteristics make each type of antenna optimal in different situations. For those networks involving more than two buildings, called multi-point connections , an omni-directional antenna at the central site will be most cost-effective. A directional antenna is installed at each remote site, aimed back at the central site omni-directional antenna. Since the omni-directional antenna transmits in all directions, every remote antenna can pick up its signal and transmit back to it.


Some examples of antennas below

Dish Antenna Omni-directional Antenna Flat Panel Antenna Yagi Directional Antenna Sectoral Panel Grid Antenna Parabolic Grid Antenna


On the other hand, some network connections involve only two distinct buildings. These are called point-to-point connections. In these situations, a directional antenna is used at each site, each aimed at the other. Both types of antennas are available with various levels of gain. Hotware-Zigwire Solution design team will provide a guide which shows some common antenna types, their gain, the maximum distance over which they are effective, and their approximate cost.

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