Everything You Need to Know About Antennas

Antennas are the most physically visible component of a wireless infrastructure. Whether it be radio, LAN, or otherwise, an antenna is extremely important. The antennas primary function is to transmit and receive clear signals between multiple wireless points. It is safe to say that an effective and efficient wireless network will require antennas to operate properly. For home, office, or outdoor wireless networks, a good antenna provides a professional solution to wireless connectivity. There exists many different types of antennas with many different specifications. To choose the correct one without understanding the nature of antennas would be an overwhelming task. Therefore, it is essential to understand the three most important specifications of an antenna, frequency, beam width, and gain, in order to choose an antenna most perfectly suitable for your wireless needs.

Frequency

Data transmission between any two points by electromagnetic waves carry a certain amount of kinetic energy therewith. This associated energy of a wave is directly proportional to the wave's frequency. The formula to calculate that energy is E = h * ν, where ν is the frequency and h is Planck's constant, 6.626 * 10-34 J*s. Therefore, the higher the frequency, the more kinetic energy the wave carries, the more powerful the wave is. Most wireless networking antennas operate at 2.4 GHz and 5.8 GHz frequencies. this is often found in wireless networks (802.11b, 802.11g, 802.11n, and 802.11ac).

Gain

Gain measures an antenna's ability to amplify incoming signals. In other words, the gain value directly determines the antenna's receiving strength. Gain is measured in dB (decibels), and is a function of the antenna's capture area and reception/transmission frequency. Larger antennas with greater capture area generally have higher gain values, as do ones operating at higher frequencies. For wide-area networks, where data transmission occur across a long-distance area, you will need an antenna with a high gain rating ( > 10 ). If the data transmission area for the antenna is in a small room, then a lower gain antenna will suffice.

Beam Width

Beam width is a measurement of the area over which the antenna receives signal. In most cases, it is measured to the "half-power points," which is the number of degrees between the points where the gain is 3 dB less than the gain for the antenna's strongest direction. Generally, the higher the gain, the smaller the beam width. An antenna with high gain and low beam width receives signals over a smaller area, but receives such signals at a strong strength (longer distance); whereas, an antenna with low gain and high beam width receives signals over a larger area, but at weaker strengths (shorter distance).

The beam width measurement for an antenna comes in two planes, the vertical and horizontal plane. When the antenna is physically positioned in the proper "right-side-up" orientation, the horizontal plane is the plane parallel to the ground, and the vertical plane is perpendicular to the horizontal plane. The below labeled pictures will assist you in further understanding of an antenna's beam width. The "A" label represents the vertical (elevation) plane and the "B" label represents the horizontal (azimuth) plane.

When browsing for antennas to enhance or build your wireless network, you might come across an "OMNI" antenna. Omni antennas are especially powerful, versatile, and useful for central access points because they have a 360° beam width in one plane or another, meaning the antenna is capable of signal reception/transmission in all directions on that particular plane.

Beam width considerations are important depending on the location placement of the antenna. If the antenna is mounted on or against a wall, then you will not need the beam width to cover the wall part of the horizontal plane. The same principle applies when mounting antennas on ceilings or to the ground. If you are using the antenna to transmit signal from one rooftop to another, then the antennas need to be mounted, such that the beam width areas are interfacing. If you are using an antenna in the center of you wireless network area, then an omni antenna is the way to go. Given so many different type of antennas and antenna placement configurations, you have a great range of flexibility and creativity in building your professional wireless network infrastructure.

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