Professor Dragan Poljak from the Department of Electronics, University of Split, Croatia, has recently presented two special seminars at Ashurst Lodge.

The first seminar was entitled, "Protecting the Infrastructure: Calculation of Induced Current and Voltage at the Pipeline Surface".

Dragan referred to the analysis of induced currents and voltages along the pipeline by means of the wire antenna theory.

Dragan presented a solution approach in three steps:

• Calculation of the electric field in the ground due to a power line
• Calculation of the current induced on the surface of the pipeline
• Calculation of the voltage induced on the surface of the pipeline

Firstly the field generated from power lines and transmitted in the ground is computed using the set of coupled integral equations. Then the current density induced on the pipleine surface is determined from the Pocklington integro-differential equation.

Finally, the voltage induced along the pipeline surface is determined by integrating the normal electric field component from the pipeline to infinity. Dragan pointed out that the Pipeline problem solution had been computed using an upgraded version of the TWiNS (Thin Wire Numerical Solver) code.

The lecture finished with a lively discussion related to particular details regarding the equivalent antenna model of the pipeline and possible improvements to approach real world scenario more accurately.

The second seminar was entitled, "Analysis of Tesla's Transmitter using the Wire Antenna Theory".

Dragan referred to the mathematical model for the radiation from Tesla's transmitter.

Dragan also discussed many interesting points from the extraordinary biography of Nikola Tesla, considered by some to be ‘the man who invented the twentieth century’.

Dragan firstly explained how the radiating part of Tesla's transmitter could be represented by an equivalent monopole antenna, end-driven via an ideal current source having replaced the Tesla's transformer. Then he presented the formulation based on the wire antenna theory and homogeneous Pocklington integro-differential equation in the frequency domain. Solving the Pocklington equation numerically via the Galerkin Bubnov variant of the Indirect Boundary Element Method (GB-IBEM) the current distribution along the equivalent monopole antenna is obtained. Knowing the current distribution on the antenna the radiated electric field is readily obained integrating the induced current along the wire.

Dragan also presented some illustrative computational results for the antenna current and related radiated field.

Finally, Dragan pointed out that the work should have been regarded as an opener to this subject, i.e. the first step in the full wave model of the Tesla's transmitter.

The lecture ended up with a quite long and very lively discussion related to the life and work of Nikola Tesla and his legacy.

Dragan holds an Adjunct Professorship at the Wessex Institute and is involved in many research activities.