Active Phase-Linear Cross-Over Network

The most serious problem with ordinary cross-over filters is best illustrated with reference to a two-way system. This con- sists of a low-pass and a high- pass filter. One of the proper- ties of a low-pass section is that it causes a time-delay of the signal. A high-pass filter on the other hand causes an acceler- ation of the signal. These ac- tions result in a number of complications at the cross-over point: (a) the signals from the two sec- tions partially cancel one another; (b)the strongly varying phase shift between the two sig- nals adversely affects the radiation efficiency of the overall system; (c) the radiation pattern becomes frequency depen- dent. Some years ago, Stanley Lipshitz and John Vanderkooy pub- lished a series of papers (1. 2. 3) that have laid the foundation of the so-called phase-linear cross-over network. Basically, the phase-linear net- work uses a low-pass section that also provides a high-pass characteristic with the aid of a time-delay and subtractio...