How Communications Towers Support Critical Infrastructure

Why Put Radio Equipment on a Tower?

Radio signals have to deal with whatever is between the antenna and the people or equipment trying to communicate.

Terrain is one of the big factors. So are buildings, trees, distance and the frequency being used.

Getting the antenna higher can help create a clearer path over some of those obstructions. That is why repeaters and base-station antennas are often installed on towers or other elevated structures.

But there is a point where simply saying “we need a taller tower” becomes too easy of an answer.

We also need to know where users actually need coverage, what frequency the system uses, what the terrain looks like and how the rest of the radio system is designed.

What Can Be Running Through a Communications Tower Site?

Two-way radio is one of the most obvious uses, especially when you see several antennas mounted on a tower. But it is far from the only system that may depend on the site.

Two-Way Radio and Public Safety Systems

A tower site may support repeaters or base-station equipment used by portable and mobile radios. For police, fire, EMS, utilities, public works and other field operations, that site can be a major part of how users communicate across a larger service area.

Some public safety sites may also support P25 infrastructure, paging, mutual-aid communications or connections between multiple radio sites.

If one of those sites develops a problem, the impact depends on the system. Users might lose coverage completely in an area, or they may simply notice that portable coverage is not as good as it used to be.

Microwave Links

Those round or rectangular dishes you see on a communications tower may be carrying a lot more than voice.

Microwave links can connect radio sites, dispatch centers, utility facilities and other locations. They can carry voice, data, control information and network traffic between sites without relying entirely on a leased terrestrial connection.

These links depend on a carefully planned path. Mounting height, dish alignment, terrain, frequency and anything that changes between the two sites can affect performance.

A dish does not have to move very far before a link starts behaving differently.

SCADA and Telemetry

Utilities and industrial operations may also use tower-based radio links to reach equipment spread across a large service area.

For a water utility, that could mean communication with tanks, lift stations or treatment facilities. An electric utility may need connectivity to substations, switches or other remote equipment.

SCADA and telemetry networks allow operators to receive information and alarms from those locations without sending somebody out just to see what is happening.

Other Wireless Connections

Some sites also carry broadband, point-to-point wireless or other data connections.

It is common for several communications technologies to share the same general infrastructure because they are doing different jobs. A utility, for example, may use land mobile radio for field crews while another wireless network handles data from remote equipment.

The Tower Is Standing. So Why Is the System Having Problems?

This is where tower-site problems can be deceptive.

A tower can look fine and still have a communications problem somewhere between the antenna and the equipment connected to it.

Water getting into a feedline or connector is one example. The system may continue operating, but performance can slowly deteriorate.

The same can happen with an aging antenna, damaged connector or feedline that is showing more loss than it should.

Microwave equipment creates another set of possibilities. A dish that has moved out of alignment may still maintain a connection while producing worse performance than it did before.

Then there is everything around the radio equipment itself. Grounding and lightning protection can be damaged. A shelter can develop a cooling problem. Backup power may not be in the condition everyone assumes it is. New antennas or equipment may have been added since the site was originally designed.

Even the area around the tower can change.

Trees grow. Buildings go up. Another radio system starts operating nearby. Any of those changes may be worth considering if system performance changes with them.

Why Tower Location Matters Before Anything Gets Built

If an organization is planning a new radio site, the location decision can affect the system for years.

We want to know what the site is supposed to accomplish before deciding where the tower belongs.

For a radio system, that means looking at the coverage area, terrain, frequency and where users will actually be operating. For microwave, we need to know whether there is a usable path between sites.

There are practical site questions too.

Can power get there? What about backup power? Can a technician reach the site after a snowstorm or severe weather event? Is there room for the equipment shelter or cabinet? What happens if another antenna needs to be added five years from now?

Zoning, permitting, structural loading, grounding, lightning protection, frequency coordination and licensing may all come into the project as well.

Those details are much easier to deal with during planning than after the tower and equipment are already in place.

What About Existing Towers?

An existing tower can sometimes be a great option for a new radio, microwave or antenna project.

It still needs to be evaluated.

There may be available height on the structure, but that does not automatically mean the tower has capacity for the new equipment or that the location gives the system the signal path it needs.

Before adding equipment, the organization may need to look at structural loading, antenna separation, feedline routing, interference, power, grounding, site access and the available signal path.

This is especially important at sites that have been around for years and have had equipment added or removed several times. The current tower may not look anything like the site that was originally documented.

What Does Tower Maintenance Actually Look For?

Maintenance is not just somebody looking up from the ground and making sure the tower is still there.

The exact work depends on the site, but there are a few areas we want to keep an eye on.

Antennas, dishes, mounts and feedlines should be checked for damage, movement and deterioration. Connectors and weatherproofing deserve attention because moisture can cause problems that are not immediately obvious.

Grounding and surge-protection components matter too, especially at sites that have been through severe weather or lightning activity.

For microwave links, alignment and actual link performance can tell us more than appearance alone.

The equipment at the bottom of the tower matters just as much. Shelters and cabinets may contain radios, network equipment, cooling systems, monitoring equipment, batteries and backup-power components.

Good maintenance records make future troubleshooting a lot easier. If test results show that an antenna system is performing differently than it did during the previous inspection, that gives the technician something concrete to investigate.

Severe Weather Can Affect More Than the Structure

After a major storm, it is natural to look at the tower and ask whether it was damaged.

That is only part of the check.

A site can remain standing while the communications system around it develops problems. Power may have failed. A generator may not have started. Lightning may have damaged equipment. Water may have found its way into a connector. A microwave path could be affected.

For systems that need to stay available during severe weather, backup power and redundancy deserve the same attention as the tower itself.

That could mean batteries or a generator at the site, a redundant network or microwave path, remote alarms or a plan for getting technicians and replacement equipment to the site when roads or conditions are bad.

When Should You Take a Closer Look at a Tower Site?

You do not have to wait for a complete failure.

If radio coverage has slowly declined, a microwave link has become unreliable or communication with remote equipment is becoming intermittent, it is worth finding out why.

The same applies before a major change.

If the organization is replacing its radio system, adding another department, expanding its service area, upgrading SCADA or planning to mount additional antennas, that is a good time to look at the tower and communications equipment together.

Storm or lightning damage is another obvious reason. So is a site with old equipment and little documentation about what has been changed over the years.

Frequently Asked Questions About Communications Towers

The Bottom Line

Most people driving past a communications tower will never know what is running through the site.

For the organization using it, that site may be connecting dispatch to field personnel, carrying a microwave link between facilities or giving a utility visibility into equipment miles away.

That is why changes in coverage or system performance are worth investigating before they become a larger problem.

If you already have a tower site, start with what it supports and how it is performing today. If you are planning a new site, start with the coverage, connections and operations the system needs to support. The tower and equipment decisions can follow from there.