Model 1100110010 is a new directional coupler operating in the frequency range of 10 to 110 GHz and offering exceptionally flat nominal coupling of 10 dB across the full bandwidth. It lends itself to wireless designs and many test and measurement applications for emerging mmWave and 5G markets, and can also be manufactured to meet military specifications. The coupler will find many uses including power monitoring and leveling in many different systems, such as antenna beamforming systems, electronic warfare (EW) systems, electromagnetic compatibility (EMC) testing, radar systems, and more. Coupling performance is 10 dB (+/-1.5) from 10 to 90 GHz, and 10 dB (+/-1.8) from 90 to 110 GHz. The directional coupler achieves frequency sensitivity (amplitude flatness) of typically +/-1.25 dB from 10 to 90 GHz and +/-1.80 dB from 90 to 110 GHz. It provides directivity of at least 10 dB from 10 to 55 GHz and at least 7 dB (and typically 10 dB) at higher frequencies from 55 to 110 GHz. For applications requiring multiple couplers on multiple channels, such as high-frequency antenna beamforming systems, the unit-to-unit coupling tolerance (coupling consistency from unit to unit) is also quite good, within +/-1.50 dB across the full bandwidth from 10 to 110 GHz.