riband for which the isolation is only about 30 dB between GSM900 or/and 1800 and UMTS bands; wideband antenna for which there is no isolation between GSM900 or/1800 and UMTS bands. Other decoupling needs: for the GSM1800 and UTRA-FDD frequencies, i.e. 1710- 1785 and 1920-1980 MHz UL, respectively, and 1805-1880 and 2110-2170 MHz DL, respectively, there is a need for 68 dB air decoupling. 7.11.1.2 Power Level Limitations Maximum power level requirements also contribute to the limitations for site co- location. Although the limits may vary from region to region, there are limits every where. Thus, unnecessary power rise in co-located sites will minimize power emission concerns. On the other hand, with the advent of WCDMA power calculations should not follow the same strictness as for GSM, because a WCDMA carrier will not be transmitting at full power all the time. The UMTS Network and Radio Access Technology CO-LOCATING ANTENNA SYSTEMS Another key issue with co-siting or site sharing is the integration of 2G/3G antenna SO- lutions. Thus, to complete the analysis of co-siting in the following we summarize the main aspects implementing antennas for UMTS and 2G systems like GSM [7]. While single band antennas can meet co-siting needs, multi-band antennas are by far the ideal solution for integrated antenna systems in co-siting spaces for 2G/3G. Multi-band antennas (i.e. dual-band or triple-band), paired with an additional diplexer or triplexer minimize the amount of antennas and feeder cables per site. On the other hand, adding diplexers to an existing system will increase losses thereby decreasing coverage. Thus, the trade has to be taken into account when completing radio planning. 7.12.1 Co-siting GSM1800 and UMTS 7.12.1.1 Single Band Due to demands for separate tilting, e.g. single-band antennas may be ideal. Figure 7.17 [7] illustrates the air-decoupling configuration for single band antennas, where separate feeder cables connect the Node B and BTS, respectively. UMTS antenna GSM 1800 antenna air decoupling Feed