We present a detailed model of the electronic detection of a single particle in a coplanar-waveguide Penning trap. The detection signal is the electric current induced upon the trap’s surface by the charged particle’s motion. In contrast to three-dimensional hyperbolic or cylindrical traps, the cyclotron and magnetron motions can be detected, excited or coupled to the axial motion without segmenting any of the trap’s electrodes. We calculate the effective coupling displacement for different electrodes. This determines the detection signal and resistive cooling time constant for each component of the ion’s motion. We discuss the practical implementation of the electronic detection for a single electron and a single proton