What is the purpose of using multiple driven elements connected through phasing lines?
To control the antenna’s radiation pattern✓الإجابة الصحيحة
To prevent harmonic radiation from the transmitter
To allow single-band antennas to operate on other bands
To create a low-angle radiation pattern
الشرح
Phasing lines set the relative phase and amplitude of the currents in several driven elements, and it is the interference among those currents that decides where the combined pattern peaks and where it nulls. Changing the phasing changes the pattern; it does nothing about harmonics or about operating on other bands.