LTE operators need to support not only the initially committed spectrum bands such as GSM900, UMTS900, GSM1800, and UMTS2100, but also spectrum bands in the LTE800, LTE1800, LTE2600, and LTE700. The network evolution boosts the deployment of multi-band and multi-mode networks for coverage. Each sector requires an antenna system for supporting multiple bands.

Traditionally, each frequency band adopts one array for independent electrical tilt. To support more bands, multi-band antennas must be equipped with multiple antenna arrays (see figure 1).

Expanding of the antenna size raises high requirements on the wind resistance and tower load bearing capabilities. To enhance strength of towers and poles accordingly, higher expenditure is required.

Figure 1 Antenna width increased by multi-array

Slim Design Technology Overview and Value

Slim design with the "dipole reuse" technology, achieving invisible upgrade to multi-band antennas.

When single-band antennas are replaced by multi-band antennas, the size of the antennas must not be greatly expanded, and therefore a slim design is adopted. Creative dipole reuse technology allows antennas to use one column to support dual bands. Build-in filters are located next to the radiation dipole, so that receiving and transmitting signals through filters achieve dipole reuse, and each frequency band can support independent electrical tilt based on separate feeding networks and phase shifters (see figure 2).

Figure 2 Slim design with dipole reuse

Two platforms, flexible combination

Dipole reuse has the low band and high band mode that can be combined flexibly. The low band dipole reuse combines 790-862 MHz and 880-960 MHz bands to share 790-960 MHz arrays, which support both L800 and GU900. And high band dipole reuse divides 1710-2690 MHz bands to 1710-2170 MHz bands and 2490-2690 MHz bands to support both GL1800/U2100 and L2600 (see figure 3).

Dipole reuse not affect antenna performance

Built-in filters feature high phase consistency, low loss, and small size by using advanced simulation methods and strict processes, which prevents the antenna performance from being affected by imbalanced channels for each antenna polarization.

By using the dipole level combiner with one wideband array, one antenna array can support two independent frequency bands, and therefore, the size of the antenna can be greatly reduced. The maximum width of the antenna can be reduced by 50% to achieve invisible upgrade when single-band antennas are replaced with multi-band antennas. In this way, both the deployment pressure and CAPEX are reduced.