Curious to know what's the current market rate for tower rental in medium and large broadcast markets.
Once upon a time, it seemed like it was $1/ft/month, at least in the smaller markets. I'm sure it's more than that today.
I've managed tower sites for a long time and have never heard that particular rate. There are a lot of variables. Too many to list here, but a few include:
1. Depending on the market size and population density, taller towers that can support more customers generally charge a premium for the higher-located tenants on the tower. For example: Say station WXYZ wants their antenna mounted right below the beacon of a 1,000ft AGL tower. They might pay $10K a month, where station WXYX is mounted half way down, paying $6,000 a month.
2. Taking into account the PCS-Cellular industry. Say Sprint wants to mount a star rack of antennas on your tower. Including calculated ice and wind loading of their proposed installation, your tower is now likely limited on additional clients such as heavy broadcast or two way customers, so you try and lock the Cell Guy's into a long term contract at a higher rate. Either that, or you might be able to focus on spreading the load out of two way or the local police and fire customers, and forget having broadcast tenants.
You only have so much capacity with headroom accounting for weather conditions on a tower, and the rates and availability vary based on the market size and available real estate without putting the tower at risk.
As urban development begins to close in to existing large tower sites of 500 feet AGL or more, it seems that a case could be made for consolidating not just AMs, but FMs as well.
AM towers are a completely different animal from FM, TV, Land Mobile, Cellular/PCS. Because of the wavelength at Medium Wave frequencies, AM Towers typically ARE the antenna, physically isolated above electrical ground with what's known as base insulators. Other towers are merely support structures for the antennas mounted on them, and are well grounded for lightning protection. There are some AM towers that support other antenna services, but it's a pain to create the proper isolation between the high RF voltage from being mounted on the antennas itself. Also since AM propagation follows the ground, AM antennas are usually located closer to a good ground like rivers or the ocean, where UHF/VHF towers are taller or on higher terrain. One also has to account for AM antennas being designed in a directional array because many radio stations have nighttime directional limitations. Between the tower height differences based on frequency, and the unique directional pattern of an existing AM station, it's not always easy to co-locate AM stations.
