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• <br /> The three types of antennas described above function on a line of sight transmission. Antennas <br /> need to be placed at specific heights in relation to one another in order to transmit and receive <br /> signals. As a result, height is a determining factor in the design and siting of wireless <br /> communications facilities. Typically, there are three types of antenna support-structures used to <br /> place antennas at desired heights: lattice towers,monopoles, and building-attached facilities. <br /> Lattice Towers <br /> Ranging from 60 to 200 feet in height, lattice towers generally accommodate a variety of users, <br /> -including cellular, ESMR, PCS and paging companies, as well as public safety communications <br /> providers. Illustrated in Figure 4, these towers generally have three or four support steel "legs" and <br /> hold a variety of antennas. They can be found in areas where great height is needed,where multiple <br /> microwave antennas are required, or where the weather demands a structurally-sound design. <br /> It should be noted that lattice towers carry an inherent tradeoff: although they can accommodate <br /> many users (and provide co-location opportunities), they often pose serious visual impacts. <br /> Equipment and antennas concentrated on one large structure tend to draw more attention than the <br /> dispersal of less visible but more numerous facilities, such as smaller monopoles or building- <br /> attached facilities. <br /> Figure 4 - WHIP ANTENNAS <br /> LATTICE TOWERS 111:1111!1!111;1, <br /> PANEL ANTENNAS <br /> DISH ANTENNAS <br /> 11// \ �i <br /> 1 <br /> 11 <br /> /I .�1 —, EQUIPMENT <br /> BUILDING <br /> 1d <br /> •Lattice towers are the least common type of antenna support structures; AirTouch and GTE <br /> Mobilnet have a combined total of seven in the San Diego region. <br /> 13 <br />