Configuring Phase Coherent RF Measurement Systems: From MIMO To Beamforming

By National Instruments Corporation

Overview

Ever since the first radio waves were transmitted, engineers have continually sought new ways to utilized electromagnetic microwave signals. While RF signals have since been used for a wide variety of applications, two specific applications that utilize one common technology are wireless communications and RADAR. In essence, both applications are unique in that they utilize the spatial dimension of electromagnetic waves. Today, many wireless communications systems incorporate multiple-input, multiple-output (MIMO) antenna schemes to take advantage of the multipath signal propagation. In addition, many of today's modern RADAR systems use electromagnetic beam steering as replacement for the traditionally mechanically steered transmit signal. These applications and others are some of the primary drivers behind demand for multi-channel phase coherent RF measurement systems.

Introduction

The modular architectures of PXI RF instruments such as the NI PXIe-5663 6.6 GHz RF Vector Signal Analyzer and NI PXIe-5673 6.6 GHz RF vector signal generator lend themselves to the phase coherent RF measurements required for MIMO and beamforming applications.

In this white paper, we will explain the technical requirements to configure a phase coherent RF generation or acquisition system. In addition, we will walk through a step-by-step process of calibrating the phase delay between multiple RF analyzers to achieve the best possible performance.