The DC 18-AQB-(***-***)-B-(**) from The Waveguide Solution is a Waveguide Coupler with Frequency 12.4 to 18 GHz, Coupling 10 dB, 20 dB, 30 dB, 40 dB, Directivity 25 dB. Tags: Broadwall Coupler. More details for DC 18-AQB-(***-***)-B-(**) can be seen below.