Cell-site capacity is a key factor for the economic health of cellular-communications service providers. One of the most promising, though technically difficult, ways to increase capacity (and implement new services) is through the use of "smart" antenna technology, which in its most advanced form, fully adapts to current traffic conditions in each cell. One of the fundamental components in these systems is a switch matrix, such as the model AY-G62S from KDI Integrated Products (Whippany, NJ), that can quickly reconfigure antenna arrays according to signal conditions.
Smart antenna systems use space-division-multiple-access (SDMA) methods to allow more than one user per communications channel. SDMA can also increase cell range by directing energy to a specific geographic area. To support these systems, a switch matrix like the AY-G62S must perform well under all temperature and environmental conditions.
The AY-G62S is a high-power, non-blocking switch matrix for operation from 925 to 960 MHz (although other frequencies can be specified) that combines any four transmitter (Tx) inputs each up to 50 W with any of eight outputs (see table). The matrix employs PIN diode switches and combiners that can handle the total 200 W of average power. The four 50-W inputs pass through double-junction circulators with isolation of about 80 dB to ensure that no power is reflected back to the Tx, while maintaining overall insertion loss at 0.3 dB for this section of the matrix. The signals are then connected to the four 1P8T switches. The circulators and switches are connected with flexible low-loss microwave cables. Reverse isolation from output to any input is 60 dB.
Directional couplers are included in the matrix to allow monitoring of forward and reflected power at each antenna output. The unit measures 14.57 × 9.80 × 2.13 in. (37.008 × 24.9 × 5.4 cm) and weighs 20 lb. (9 kg). A wide variety of configurations can be provided in wireless bands through 2.6 GHz. MCE/KDI-Integrated Products, 60 S. Jefferson Rd., Whippany, NJ 07981; (973) 887-5700, FAX: (973) 884-0445, e-mail: [email protected], Internet: www.mcekdi-integrated.com.