Book review of "MIMO radar: Theory and application"

MIMO radar is a very controversial hot topic. MIMO radar researchers have claimed 10 dB or 20 dB advantages relative to boring old phased array radars, but crusty old radar engineers have doubted such assertions and poked holes in their analysis. Ten years ago the Office of Naval Research (ONR) asked me to become embroiled in this debate, resulting in [5]. The authors of this new book tackle this problem head on. In particular, they say clearly and emphatically that: "The hype surrounding MIMO radar has come with a fair amount of skepticism. MIMO radar is not a cure-all for every radar problem…. Unfortunately, the benefits of MIMO radar have sometimes been overstated, which has created a cloud of controversy that has generally slowed its adoption for radar modes and applications where it could have great benefit. In this book we attempt to present a fair analysis of MIMO radar technology in a way that clearly highlights its benefits and pitfalls" (page 11). In this review, we shall see how well the authors have succeeded at this task. For example, on pages 72 to 75 there is a nice simple analysis of the bad impedance match of a typical MIMO antenna with free space, which results in a very poor radiation efficiency, and hence potential damage to the radar transmitter. That is, if the microwave energy is not radiated into free space, then it stays in the transmitter, which heats up and could suffer severe damage. That is, the typical MIMO antenna does not radiate efficiently like a boring old phased array radar or an extremely boring old dish radar. In fact, the MIMO radar transmitter might actually melt as a result. This is a simple fact of physics, first explained by Oliver Heaviside [9] well over one hundred years ago, and it is taught to every student of antenna design or electromagnetic physics. Unfortunately, the authors do not mention that there is a very simple solution to this problem: design the MIMO transmit pattern in beam space rather than element space, in which each beam is designed with high efficiency of radiation as explained in [3]. About 15 years ago a famous MIMO radar researcher (who will remain nameless) once visited us to extol the virtues of MIMO radar, and one of our smart aleck antenna designers in the back of the room pointed out that the MIMO transmitter would melt, to the eternal embarrassment of the famous professor.