Comparison of GTD with compensation theorem for finite size knife edges

The application of the geometrical theory of diffraction to radio wave scattering by edges which are infinitely long is well established. The technique has also been applied successfully to edges which are relatively short in terms of wavelengths, but no quantitative measure has previously been available to say how the error increases as the length of the edge decreases. In contrast, the compensation theorem is a perturbation technique which increases in accuracy as the size of the perturbing structure gets smaller. A comparison has therefore been carried out between the results of the two approaches, applied to radiowave propagation over a finite height and finite width rectangular conducting plate. In the associated experiments the heights of the transmitter and receiver were kept at ground level, to simplify both the analysis and the experimental operating procedure.