The guided wave technique is an ultrasonic technique which is used to monitor large structures in a variety of industry sectors to safeguard against catastrophic failure. The guided wave technique for pipeline inspection has been commercially used since the early 2000s and this facilitates rapid inspection where from a single location over 100 metres of pipeline can be inspected. This technique is currently being used in pipeline infrastructure across the globe. For the technique to be successful it is highly dependent on a numerous of factors including, frequency selection, array designs and pipeline geometries. The transducers used on pipeline are dry coupled and the magnitude of the signal transmitted is dependent on the normal force applied to it. If this force is not controlled the signal being transmitted can degrade and lead to the difficult analysis of a complex signal. In this thesis studies have been undertaken to understand the relationship between dry force coupling of the transducer and the signal received, aligning this connection to classical contact theory. This is then further to extended to the influence surface contact conditions have on the transmission of signal from the transducer. Analysis of the results detected a peak in the operational frequency response which in turn initiated electrical impedance and structural resonance measurements to identify the presence of resonances which are induced by dry coupling. This behaviour was then modelled in FEA software and the validity of the FEA approach was tested against several prototype transducers. This thesis has been funded in joint collaboration between the Engineering Physics and Science Research Council and TWI ltd.