Two-Probe Coaxial-to-Coplanar Dual Directional Coupler for 2.45-GHz ISM Measurement Applications

Abstract

A 2.45-GHz directional coupler with coplanar output is described whose main arm is a section of EIA 7/16" coaxial line. The coupling is established by means of two electric probes extending into the coaxial line interior. The two coupled signals interfere in an external coplanar waveguide interconnecting the probe outputs. The coupling factor can be set in a wide range by the probe lengths. The directivity exceeds 25 dB in the range 2450+25 MHz. The structure is suitable for constructing a dual directional coupler/detector.