Week 2 iLab Report
DeVry University
NETW360: Wireless Technologies and Services

ANTENNA TYPES AND COMPUTE RF BEHAVIOR

Submitted to:
Professor
Date: 1/18/14

Antenna Types
Directions: Provide the basic differentiating characteristic of each of the three antenna types listed below. Also provide that typical use of the antenna type.

1. Omnidirectional:
The basic differentiating characteristic of an omnidirectional antenna is that it radiates its signal out equally in all directions depending on the antenna’s orientation. If the antenna is placed vertically the signal will radiate horizontally equally in all directions and if the antenna is placed horizontally the signal will radiate vertically equally in all directions. Omnidirectional antennas have 360 degree coverage, but not completely equally in all directions as I will discuss next. The omnidirectional antenna is most commonly used in a vertical position so that it can radiate most of its signal outwardly in horizontal streams on both sides of its location, however a small part of the signal will radiate up and down vertically. Although, it is most commonly used in the vertical position, an omnidirectional antenna can also be used in a horizontal position to radiate most of that signal vertically (up/down) with a small portion of the signal radiating sideways (horizontally). The reason for this mismatch of signal strength due to the vertical/horizontal placement of the antenna is because the signals strength radiates 90 degrees outwardly from the antenna’s orientation.
The omnidirectional antenna can be used indoors and outdoors, but for this course I will discuss the indoor use which is most typically used in an AP (access point) for indoor WLANs where users are all on the same floor, which usually requires a broad, horizontal coverage area. Thus having the antenna positioned vertically will provide the best radiated signal reception for users on that same floor. APs using an omnidirectional antenna should be placed in the center of the coverage area. To delve a bit further, the most common type of omnidirectional antenna used for WLANs is a thin, straight metal rod encased in plastic, called a dipole antenna. These diploe antennas are located on APs and are usually hinged so the antenna can be turned 90 degrees in the horizontal position to provide increased coverage vertically, if needed. In addition omnidirectional antennas are used for cellphones, cordless phones, portable radios, and radio broadcasting.

2. Semidirectional:
A semidirectional antenna radiates its signal in one single direction, 180 degrees or less. Semidirectional antennas can also be used indoors and outdoors, but as opposed to omnidirectional antennas, they are not commonly used for indoor WLANs. If a semidirectional antenna is used for indoor purposes it’s generally used for a group of users who are clustered tightly together where a broad coverage area is not needed. In that particular scenario the AP which is housing the semidirectional antenna should be placed in one corner of the room where it can be focused to the clustered group of users. Another way that a semidirectional antenna is different than an omnidirectional antenna in that they can be installed high on a wall and tilted downward toward the coverage area. An omnidirectional antenna cannot do this without causing the signal on the other side of the antenna to be tilted upward.
Semi-directional antennas are used for short to medium distance communications and is commonly used to provide a network bridge between two buildings in a campus environment or down the street from each other. Basically this is a point-to-point configuration in where two buildings are connected via a wireless network. Now that I am thinking about the aspects of a semidirectional antenna, I think that they would work well in facilities with long rows/corridors stacked high like in factories, warehouses, libraries, and hospitals. See these semidirectional antennas can focus their signals down the long corridors.
Although, I know it is not needed for this question, I want to close with the some types of semidirectional antennas which are sectorized, patch, panel, Yagi.

3. Highly-directional:
Highly-directional antennas are different than semidirectional antennas because of their shape, duties, and high gain. They are reflective, parabola shaped devices that cast narrow signal beams very long distances. Whereas semidirectional antennas focus their signal in one direction, but nowhere near as far as a highly directional antenna. The reflector of a highly-directional antenna creates a large surface area that the antenna uses to receive and transmit signals. The shape of the highly-directional antenna allows it to concentrate the signal into a transmitter/receiver that protrudes from the center of the antenna (dish). They have the most focused, narrow beamwidth of all the antenna types. As opposed to an omnidirectional antenna, a highly-directional antenna will not respond to incoming signals coming from any other place than the one they are directed to, thus decreasing interference. Highly-directional antennas differ from semi and omnidirectional antennas because they are more sensitive to wind loading. The slightest change in its position can cause a highly-directional antenna to aim its signal away from the receiving antenna.
Highly-directional antennas are strictly used for outdoor, long distance, point-to-point communications, and usually provide network bridging between two buildings. Highly-directional antennas are not used for indoor WLANs. The two types of highly-directional antennas are parabolic dishes and grid antennas. The latter is less vulnerable to wind loading because the spacing between the wires allows the wind to freely whistle through it.

The chart below illustrates some additional differentiating characteristics between the three antenna types.
Antenna Type Maximum Azimuth (degrees) Maximum Elevation (degrees)
Omnidirectional 360 90 Semidirectional 135 65
Highlydirectional 16 21

Directions: Perform Project 4-1of your textbook, page 152. Record your calculated answer, with the appropriate units of measure for the assigned Steps below.

Calculations Step 4 : 30 dBm Answer Units of Measure Step 7 : -0.367 dB Answer Units of Measure Step 11 : 8.4 dB Answer Units of Measure Step 15 : -81.561 dB Answer Units of Measure Step 17 : -88.361 dB Answer Units of Measure Step 19 : 9.438999999999993 dB Answer Units of Measure Step 23 : 1.0986115639392535 meters Answer Units of Measure Step 28 : -5.474469367710745 dB Answer Units of Measure
References
Guidelines * Include all references used to complete this iLab. This must be in APA format.

Ann, J. (n.d.). Advantages of a highly directional antenna. Retrieved from http://www.ehow.com/list_5990165_advantages-highly-directional-antenna.html
Ciampa, M. (6/19/12). CWNA Guide to Wireless LANs, 3rd Edition. Retrieved from http://online.vitalsource.com/books/9781285529080 eHow Contributor. (n.d.). The types of wireless antennas. Retrieved from http://www.ehow.com/about_5421331_types-wireless-antennas.html

Rouse, M. (2012, March). Omnidirectional antenna. Retrieved from http://whatis.techtarget.com/definition/omnidirectional-antenna
Ucu , S. (2008, Nov. 05). Wireless antenna types. Retrieved from http://setup- wireless.blogspot.com/2008/11/wireless-antenna-types.html