Energy patterns of pulsed antennas illustrated with a reflector type of an impulse-radiating antenna (IRA)

A question that often comes up in the context of an IRA is, “How is the transient energy from the pulser radiated in space”? Of course, the electromagnetic fields (both Ε and H), the power density, and the energy density have their maxima on the boresight. The power pattern is a well-defined frequency-domain concept, but it is a cumbersome descriptor for hyperband antennas such as an IRA because of the multitude of frequencies involved. In this note, we explore the concept of an energy pattern that holds good both in the time and frequency domains. An energy pattern is useful in visualizing where the transient energy provided to the IRA is going. It is further noted that the energy and power patterns are identical for a CW antenna, while they can be vastly different for pulsed antennas.