The introduction of active antenna systems in 5G-New Radio (NR) requires installation and maintenance engineers to use alternative test methods, such as Effective Isotropic Radiated Power (EIRP) for transmitter power and beam verification. Gone are the days of simply measuring transmitted power with an absorption power meter or using a direct connection via a “sniffer” port in the antenna feed. A new generation of field solutions must be employed to conduct these measurements. This article covers the fundamentals, the challenges, and the best practices of EIRP testing in installation and maintenance of 3GPP 5G Next Generation base stations (gNB). The key specifications that a spectrum analyzer needs to ensure accurate EIRP measurements are also discussed.
What is EIRP?
Before the advent of 5G, radio systems, whether cellular, PMR, broadcast, or military, all used relatively simple transmitters and antennas. Knowing antenna gain and input power, one could predict signal strengths and hence validate a base station, ensure safety and analyze performance indicators. Today, this is no longer the case. 5G networks involve complex active antenna systems, imposing significant changes in the installation and maintenance of base stations. This complexity is necessary to achieve the efficiency and speeds of 5G. Using traditional methods to conduct measurements has become impractical and, even when possible, the results have little relationship to the network’s performance.
Everyone involved in 5G networks has different priorities: mobile operators need to assess the quality of User Equipment (UE) connections and map field coverage; engineers installing and maintaining 5G base stations must verify transmitted power and beamforming; regulators need to ensure and assess compliance with electromagnetic levels, as well as enforce spectrum clearing. Effective Isotropic Radiated Power (EIRP) – a product of transmitter power and antenna gain in a specific direction relative to an isotropic antenna – is certainly among the indicators that help determine the performance, safety, coverage, and compliance of a 5G network.