Compact high power wide band coupler

A description is given of a technique to flatten the normal 6 dB per octave amplitude response of short TEM mode couplers. The coupled port is impedance matched, and the through path insertion loss can be limited to coupling loss and normal transmission line loss. The latter will be very small because of the short length of the primary line. A 10-dB coupler covering an octave band is not a problem. The technique is based on the combining of several coupled signals with their phase and amplitude proportioned to cancel the increase in coupling as the frequency increases.<>