This response characteristic is said to be one of the major advantages of a dipole bass system, as the restricted dispersion results in fewer boundary reflections, which in turn is supposed to result in a smoother in-room response. A completely circular baffle will produce the worse response characteristics, with deep nulls at multiples of Fpeak. From the table, it's plain to see that it's nearly impossible to push Fequal much lower than 80 Hz unless a fairly large baffle is used. OTOH, the larger the baffle, the higher the efficiency, but response at the upper end of the passband could get somewhat irregular as Fpeak is reduced. Almost all dipole bass designs incorporate some means of boosting the response at low frequencies to compensate for the baffle loss.
Active equalization is used to boost the low frequency response.
Active or line-level filtering is used to cut the higher frequency levels to match the low frequency response.