SpectrumTalk

Antennas & NIMBY
Part 1

Wireless systems need antennas. Many types of modern commercial wireless systems such as cellular radiotelephone and fixed wireless access systems need antennas sites throughout the service area with spacing of 1-10 km, depending on population density. These systems already require many antennas and will need more in coming years for a variety of reasons. NIMBY (“not in my back yard”) opposition to antenna siting in suburban areas is already a major issue in the rollout of new wireless services and is likely to worsen in the next few years. This blog entry will examine the nature of this problem. Future entries will review the regulatory response, and possible alternative approaches to defuse the situation.

This problem is most severe in suburban areas. In urban city cores it is relatively easy to place antennas on tall buildings with willing landlords and little visual impact. Generally, it is also easy to place antennas in rural areas where short spacing is not needed and antennas can usually be sited away from residences. But in suburban areas one has a bad combination of factors: need for close spacing of antennas due to population density, lack of tall buildings, and neighbors who are inevitably close to antenna sites.

How many antennas are needed in suburban areas? The FCC has estimated that in 2005

• “roughly 268 million people, or 94 percent of the U.S. population, live in counties with four or more mobile telephone operators competing to offer service. In addition, roughly 145 million people, or 51 percent of the U.S. population, live in counties with five or more mobile telephone operators competing to offer service, while 50 million people, or 18 percent of the population, live in counties with six or more mobile telephone operators competing to offer service.”

This was before the FCC finished auctioning off 6 licenses in each area for 3G cellular, formally call Advanced Wireless Service in the U.S. Now not all the new 3G license will result in new systems independent of the existing systems, scenarios with 10 mobile systems each with antenna requirements are possible.

At the same time interest in Fixed Wireless Access (FWA) is increasing with the new 2.5 GHz Broadband Radio Service as well as previously existing bands. FWA systems in a given location might number in the 5-10 range in the next decade. Thus the total number of independent antenna systems needed with spacing in the 1-10 km range may well be 15-20 in the next decade. This does not include public safety systems that may migrate to a cellular architecture to increase capacity and use higher frequency bands.

Antenna systems in suburban locations often arouse objections from neighbors. Sometimes these objections focus on RF safety issues, even though human exposure from such systems is almost always significantly less than generally accepted safety levels. Another issue, and one that may trigger the RF safety concerns, is that most suburban antenna systems “look like they were designed by engineers”! That is a common tower holds multiple antenna systems at different heights that appear to have been selected independently, perhaps with consideration for the maximum visual discordance. Depending on the local cell structure, similar antennas may be rotated in the horizontal plane with respect to each other.

The usual industry reaction to neighborhood opposition is building camouflaged towers, perhaps looking like trees, or trying to incorporate antennas into an existing high structure such as a church steeple or even building new steeples! These solutions are very expensive and of limited applicability, especially if a large number of antennas are needed at the same location.

[More next time on FCC attempts to deal with this issue and possible alternatives to break the stalemate.]