132-137, Aa2-jm-99.09.13

The rapid growth in the number of users of mobile communications means that many operators must find new ways of increasing the capacity of their networks. Their options include allocating more frequency, introducing frequency-hopping techniques, and adding microcells and adaptive antenna systems. The introduction of new frequency bands at 1800 and 1900 MHz is an example of allocating frequency to increase capacity. However, compared to 800 and 900 MHz systems, mobile communication at 1800 and 1900 MHz requires more base stations or greater levels of radiated power. Within the available frequency spectrum, capacity can be increased through the introduction of smaller cells, such as microcells, to create a dense network of base stations. Nonetheless, networks of this kind are often perceived as an aesthetic eyesore, due to the large quantities of associated antenna installations. Indeed, in many regions, the general public demand is for fewer antennas that are smaller in size and less conspicuous. Another problem associated with adding numerous base stations is the cost involved in finding new locations for the antennas and base-station cabinets. Therefore, more and more operators are showing interest in adaptive antenna systems as a means of resolving their need for greater network capacity. Ericsson has conducted extensive research and development of advanced base-station antennas for mobile communication. This work comprises both adaptive and active antenna systems. With the introduction of active antenna products, such as Ericsson’s Maxite products, operators can now use small-sized base station units with high levels of equivalent radiated power (ERP) and low power consumption. Ericsson has vast experience of array antenna products which, thanks to a superior design practice and the integration of antenna and electronic components, make attractive system solutions. Product examples found in commercial and defense applications include • Maxite active antennas (Figure 1); • the MINI-LINK family (Figure 2; • Erieye airborne early-warning radar (Figure 3); and • Arthur artillery hunting radar (Figure 4).