Multitenant towers

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As wide-open areas suitable for tower erection decrease in availability, vertical real estate is becoming increasingly attractive to potential broadcasters. The use of somebody else's tower can be attractive, but before rushing into a contract with an existing tower owner, consider all the problems that can occur as well as the FCC requirements and rules.

Urban growth and an increased need for vertical space have made tower space more valuable. In addition, most communities frown on building new towers despite the increased need.

Adequate and comprehensive insurance is essential. There must be no question as to liability of the landlord or of the tenant in the event of catastrophe attributable to technical operation.

From an existing tower owner's point of view, renting space may offer an opportunity for tax write-offs by donating tower space to religious broadcasters and other charitable institutions. When properly handled, it might turn the engineering department into a profit center. This would earn the respect and appreciation of the general manager who would be pleasantly surprised to see money flowing into the engineering department instead of out.

On the other hand, a new station might find leasing space on an existing tower to be preferable to a large capital expenditure. Lease renewal options are important and long-term leases are essential for stability. If you had difficulty finding a suitable site in the first place, it is not likely that any more suitable sites will become available as time passes. On the contrary, normal industrial and urban growth will continue to consume open areas, and FAA and zoning restrictions are likely to become more difficult as time passes. These factors can only increase the value of a tower.

A 20-year lease with renewal options would be ideal, but is not always possible. There is nothing worse for a licensee than to have his antenna site taken from him. I recall the case of a station with a four tower, widely-spaced rectangular array on land that used to be a desert. The land suddenly became valuable as a potential mall. The original lease had an option to renew but there was no price protection. As a result the station went dark and the mall was built.

What can happen if an existing AM operator is preparing to rent space on his tower to an FM broadcaster? This situation is fraught with complications if the AM general manager and his chief engineer do not sit down and prepare a list of technical problems that must be solved and completely covered in the contract. The general manager and the station's attorney must also draft a satisfactory and comprehensive lease. At this point, the chief engineer should be involved in all the technical requirements. If this procedure is followed there should be no difficulty in consummating a satisfactory tenancy.


Responsibility for tower lighting is often the cause of FCC violations. Proper understanding of the new tower registration requirements and the divisions of responsibility for lighting in the Commission's new rules should eliminate confusion.

A large amount of money will be spent adapting the AM tower to carry the FM radiator. Isolating the tower and feeding the new FM antenna can be accomplished by using an isolating coil or converting to a grounded folded unipole radiator. The former method is less costly, but the latter provides the possibility of added revenue without further expense, if the tower can support additional radiators.

While AM towers can be used for additional tenants, additional costs will be incurred.

Provided that the tower can support the additional antenna and the weight and wind loading of a folded unipole, the grounded tower is optimal because lightning problems should be greatly reduced, signal improvement may be noticed and the potential exists for additional tenants without the need for any additional antenna changes.

Another important point that can be overlooked is “down time.” The FCC requires that non-ionizing radiation be reduced or eliminated during work on antennas and towers. This means completely shutting down all transmitters or operating with reduced power.

The AM transmitter will have to be powered down while the AM tower changes are being made. Who will pay for this lost time? Converting to a folded unipole will take longer and require even more down time. Installing the FM antenna and transmission line can be performed while adding the folded unipole.

If another AM station is to be added to the existing operation (i.e. diplexing), problems of down time should be fewer. No antenna changes will be required, and new transmitter and coupling equipment construction can continue without interruptions to the existing AM operation until the time comes for the eventual connection and tuning. Such diplexing will result in additional cost to the landlord in the provision of filters and system retuning. In addition, the cost of the landlord's lost air time will have to be covered in the leasing agreement.

Adding an FM antenna to an existing FM tower involves a tower study to make sure it's safe. If using a wideband common antenna and transmission line, be sure to spell out the individual responsibilities and performance requirements in the event of RF problems. Such a proposed installation requires thorough engineering examination prior to drawing up contracts.

It seems that the trend is toward multiple tenants on towers. Certainly in cases of antenna farms and specific tall buildings, multiple tenants have a long history of successful operation. For smaller stations in individual markets, multiple tenancy is becoming a viable solution to the lack of open space, FAA restrictions and shortsighted state, county and local zoning boards that bow only to the public utility denominator.

E-mail Battison at

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