Cellsites

Cellsites are the relay stations that connect cellphones to the fixed telecommunications infrastructure (now mostly fibre optic cables) running up and down the country. When someone makes a call, or connects to the internet, from their cellphone the phone establishes a radio link to a nearby cellsite and the call or data is transferred over this link.

The radio signals from the cellsite are transmitted from antennas that are some distance above the ground. The antennas are designed so that most of the radio signal is transmitted outwards, at a few degrees below the horizontal. Comparatively little is transmitted at steep angles down towards the ground close to the site, and very little indeed comes from the back of the antenna. Because of this:

Exposures on the ground around a site are usually quite low close to it, and higher further away.
If there is a house close to a site, most of the radio signal is several metres above the roof, rather than being directed into the house.
If the antennas are mounted around the roof of a building, exposures to radio signals inside the building are usually much lower than outside it, or in buildings that face the antennas.

Simplified example showing where most of the radio signals are transmitted from a cellsite with three antennas

How the strength of the radio signal at ground level (ie the exposure to the radio signal) varies as you move away from the site. The highest value usually occurs several tens of metres away from the site.

Exposures to the radio signal

Measurements around several hundred sites in New Zealand show that the maximum exposure to the radio signals around a cellsite is typically less than 1% of (ie more than a hundred times below) the limit set for the public in the New Zealand exposure Standard. In most places, they are lower still. The same applies even if several sites are closer together. Once you are a few tens of metres from the site, the exposure decreases quite quickly as you go further away. If a direct view to the antennas is blocked by trees or buildings, the exposures are also much lower.

Exposures inside a house are much lower than outside, because the roof and walls block a lot of the radio signal.

Exposures near sites that look physically imposing - tall, large diameter towers - are almost always lower than near sites that are physically smaller. the reason for this is that the antennas are further away from where people might be, and that extra distance means the exposures are lower.

How can I find out about a site?

GISGeek (registration required) has an excellent site presenting information about cellsites around the country, drawn from the Radio Spectrum Management licensing database.
Your local authority should receive information about sites in their area - this is required by the National Environmental Standards for Telecommunication Facilities. Amongst the information they should receive is a report about exposures to the radio signals from the site, and whether they comply with the limits in the New Zealand exposure Standard. If exposures in public areas could exceed 25% of the limit, the site operator is required to provide evidence (usually measurements) confirming compliance with the limits once the site is operating.
You can always get in touch with the company operating the site.

Cellsites

Exposures to the radio signal

How can I find out about a site?

Where can I find more information?

On this site

Other links