In this thesis I will discuss the modelling and testing of THz and microwave emitters. I firstly present a new model for the lateral photo-Dember effect and find that the previous 1D model by Barnes et. al. is incomplete. I use a 2D solution of the drift diffusion equation and feed the currents in to a finite difference time domain algorithm. In order to have a realistic representation of the far-field to the detector I use a far-field algorithm. I show that the dynamics of the system are dependent on the currents travelling perpendicular to the semiconductor surface, as opposed to just the lateral currents as previously thought. I then go on to compare this model with experimental results. The experiment in question involved the examination of photo-Dember emission when the semiconductor is under the influence of a biasing electric field. I also performed a separate experiment in which a gap was introduced to various lateral Photo-Dember emitters in order to observe its effects in both the time and frequency domains. I also present a novel microwave antenna based on the fishscale and split-ring resonator metamaterial designs. I demonstrate that mutual coupling between the fishscale and SRRs is responsible for creating a greater absorption of the input signal than either component is capable of in isolation. The antenna was tested, and I compare the experimental results with the computational model.