Details

New Mobile Telephone Sites by means of Calculation - Sponsor Funds Invested Sensibly

 Mobile telephone networks form nowadays an essential part of the basic infrastructure of a country. The majority have long become accustomed to being able to use mobile telephones everywhere and at all times. However the setting up of new mobile telephone transmission units meets increas-ingly frequently with massive resistance from the local population. In order to improve the acceptance of the further network extensions, the mobile telephone operating companies have taken the initiative and already de-clared themselves willing in a voluntary statement made to the Bavarian State Government that they will set up new transmitters consensually with the towns and communities. In addition, they wish to minimise the number of the required locations on the basis of the currently valid limit values by joint usage – in as far as this is permitted under antitrust laws.

As the Federal Government has, with respect to the extensions of the mo-bile telephone networks, not yet set in force any regulations, the Free State of Bavaria has gone on the offensive. Thus the Bavarian Ministry of the Environment has set up a sponsorship fund with which communities are to be supported in the location search for the unpopular transmission units. Altogether 4 Million DM will be made available from the budget. The new FEE-Program provides a 50 percent subsidy and is needed to run until the end of 2002. The subsidy sum of 5.000 € can be applied for on a one-off basis by all Bavarian towns and communes from the ministry. Consultancy, the register compilation of excising units, comparable measurements be-fore and after a construction measure and forecasts by means of calcula-tions are funded.

In order to review whether mobile telephone transmission units conform at the projected sites to the limit values in the sensitive areas as well, two dif-ferent methods are used: on the one hand, the comparative measurement of the electromagnetic immission before and after the building measure and, on the other hand, the forecast by calculation of the wave propagation by means of calculation.

Even if the first method is used very frequently, it reveals a number of dis-advantages. In particular the measurements are both time-consuming and expensive if differing radio transmission services such as D-Netz, E-Netz, UMTS, TETRA-Dienste etc. are to be taken into consideration in the selec-tion of the site. Moreover the Actual Status can first be established by means of measurements when the transmission unit has been completed, i.e. the building measures have been concluded.

Calculations provide considerably quicker and more cost-effective solutions to such questions is the view of EMC experts of the firm of IABG in Otto-brunn near Munich. The company itself has an own laboratory, accredited by the Bayerisches Landesamt für Umweltschutz (Bavarian State Agency for Environmental Protection), for the measurement of electromagnetic fields in accordance with DIN VDE 0848 and thus knows both methods from its daily business practice.

Thus the expensive investments in infrastructure could be put back for so long until planning reliability with respect to the actual EMC loading had been achieved. Accordingly the exact Actual Status is calculated without measurements having to be taken on site, when transmission performance and radiation direction of existing units are known. A further advantage over the field measurements is seen by the experts as being the possibility of being able to determine quickly potential alternative locations for transmis-sion masts by using computational simulation. From these calculations is clearly demonstrated in which area mobile telephone transmission units could be operated with which level of performance and at which frequency, so that in the sensitive areas the proposed limit values could be adhered to.

The results of the calculation are summarised on a map on which the com-pliance of limit values is clear or the maximum permitted performance of a mobile telephone transmitter unit can be derived. This map can be used in the negotiations with the mobile telephone network operators and for objec-tive decision-making within the community.

The basis for the calculation is always an individual and tailor-made topo-logical model of the community. The data for this model, as is well known to IABG, have long been compiled for Bavaria and can be procured from spe-cial data banks. Such a digital terrain model describes completely the three-dimensional morphology of the terrain to a degree of accuracy of a few centimetres with all its elevations and depressions. There the soil com-position is deposited for example, i.e. whether it is woodland, meadow, a fallow area or the surface of a lake. With the help of these details, it is then possible to predict exactly, how the electromagnetic waves react in the ter-rain, i.e. how and where they are refracted and reflected in the terrain.