How Tall Do Cell Towers Need to be in Order to Be Effective?
For this reason, if zoning allows a tower to be just above 200 feet tall, tower developers would rather just build a 199-foot cell tower to avoid the maintenance cost. If a tall tower is to be built at all, developers would rather build 300-foot cell towers because they are more valuable to wireless carriers because of the added reach of the cell signal, thus the increased value would outweigh the lighting maintenance burden.
In metropolitan areas, aside from zoning height restrictions, RF engineers limit antenna heights due to spectral efficiency concerns. Wireless carriers must pay the Federal Communications Commission (FCC) the right to operate in certain frequency (spectrum) bands. In major metropolitan areas, AT&T, Verizon, and T-Mobile must outbid each other in spectrum auctions by paying the FCC tens of billions of dollars for the spectral right to operate in any major cities. With spectrum in limited supply and outrageously expensive, wireless carriers must use each frequency very efficiently. One way to do this is keep the cell towers as low as possible so the frequencies do not travel very far. By limiting the reach of each tower antenna, that same frequency can be reused again and again in the same city. The downfall of this design principle is that many shorter towers will need to be built in order to improve the spectral efficiencies defined by radio frequency (RF) engineers. In these situations, it is ironic that building shorter cell towers is cheaper than paying billions of dollars for more spectrum. Often, in a rooftop tower build in downtown situations, the tallest building is not the right building for antenna placements. One way we remedy this situation is to install the antennas on the exterior of the building, lower than the roof height in order to meet the spectral engineering requirements.