L-Band Satcom

L-band satcom uses roughly 1 to 2 GHz (about 1.525 to 1.559 GHz downlink, 1.626 to 1.660 GHz uplink for the maritime mobile-satellite service) and is the resilient narrowband backbone of maritime communications. Inmarsat (BGAN, FleetBroadband, Inmarsat C) and Iridium operate in L-band. Its long wavelength resists rain fade and needs only a small, low-gain antenna, so it stays available in weather that drops Ka or Ku broadband. The trade-off is low throughput, which is why L-band serves as GMDSS safety and as the automatic failover beneath high-throughput services.