Closed form expression for transient fields in a voltage fed cylindrical open cavity

Electromagnetic transient analysis is enjoying renewed interest as the growth in computer processing power and storage capacity is making numerical methods such as finite difference time domain attractive for many engineering problems. Nevertheless, analytical techniques are still important for electrically large structures and closed forms are desirable in terms of computational convenience, physical interpretation and as a reference for numerical solution techniques. In this paper a near exact closed form solution is derived for the transient field in a voltage fed cylindrical cavity. This solution includes both the TEM and TM waves which result from considering the initial transient of the excitation.