Traditionally cellular radio antennas are connected to base station radio equipment using coaxial feeders, which carry the baseband frequency and the RF signal. RF feeders have served the industry extremely well, however, as the frequency and the bandwidth transmitted increases, the losses in the feeder and connectors become more significant.
Modern cellular equipment utilizes remote radio unit (RRU) or remote radio head (RRH) that is fed from the base station via optical fiber. This eliminates the loss issues on feeders and allows transmission to occur at much higher frequencies and with larger bandwidth. The snag with this method of transmission is that power cannot be transferred from the base station to RRU or RRH via the optical fiber. This power is fed separately as DC on copper cables that are either separate to the fiber or are a composite fiber-copper cable.
The DC feed acts as a source of lightning surge back into the equipment room and more precaution needs to be taken on how to control these surges, than ever before. In traditional radio, the extent of damage to equipment would normally be the radio equipment. In the modern scenario damage can occur to the rectifiers or the whole DC power system, which would jeopardize other equipment installed at the site. The simple solution to this may seem like installing surge protection devices or SPD on the DC feeds. However, there are intricacies that involve earth loops & voltage drops associated with cable lengths that need to be understood before choosing the correct location of SPD. DC SPD’s typically deplete with number of surges and attention needs to be paid to alarming and monitoring of these.
During this session, discussion will be held on: scenarios of where SPD’s are typically located; the tricks and traps that must be avoided in choosing the DC SPD location; and modern methods of distributing DC Power to the antenna.
Director of Sales