Engineers turn to multi-antenna techniques to achieve diversity, multiplexing, or antenna gains. Through these gains, the wireless systems can increase the receiver’s robustness, data throughput, and signal-to-noise ratio (SNR). Testing multi-antenna systems requires a test system capable of providing multiple signals and a constant phase relationship between the signals. However, a commercial signal generator has an independent synthesizer to up-convert an intermediate frequency (IF) signal to an RF signal.
In Part 1, we explored multi-antenna techniques and their test requirements. In addition,we discussed how to synchronize multiple base-band generators and tips to minimize the LO’s phase difference between signal generators.For some applications, such as beamforming systems and component characterization,test signals must be coherent and have a specific phase relationship. This requires signal generators to have a phase-controllable capability. In this paper, you will learn how to configure a phase-coherent and phase-controllable test system. We will start with the concept of phase coherence and why it matters.
