The first stage in selecting a site is to look for an existing site which might appear to cover the service area. Information may be available from the operators of such sites regarding their coverage, and coverage tests may be made or computer predictions obtained. For a
214Table 19.1 Factors affecting the decision to own or rent Ownership Rental
Initial costs Legal charges
Land clearance
Provision of services Erection of buildings
and mast or tower Installation of equipment Provision of standby power
Recurring costs Maintenance of site Power
Insurance (other than
Other considerations Very long
commissioning time Site under user’s control
Space may be leased to other users
creating revenue Legal charges Connection fee
Rental
Normally included in rental Normally included in rental
Very short
commissioning time
Site under landlord’s control
Accommodation will be shared with other users (install equipment in
locked cabinet to
preserve security)
receiving site the ambient noise level at the base station must also be considered. It should be realized that a site, or an antenna, can be too high, particularly when coverage is required at very short range or if interference from other users is likely to occur. Antennas radiate the minimum signal along the line of their elements so that vertically polarized antennas, i.e. with the E plane vertical, provide very little, if any, signal immediately below them. This creates a hole in the coverage, ‘the Polo mint effect’, close to the antenna.
Where there is capacity on an existing site the possibilities are:1. Sharing an existing lightly used radio channel, e.g. common base station.
2. Sharing equipment space in an existing building or providing own building or extension on a communal site.
3. Sharing an antenna by means of multi-coupling or erecting own antenna on existing structure.