A terrain-based propagation model for vertically polarized radio waves is described, based on the field integral equation for a smooth surface. The model is simplified from a 3D integral equation model to a one-dimensional integral equation by assuming that the surface is magnetically perfectly conducting (a soft surface) with no transverse variations. By assuming no back scattering, the integral equation is turned into a simple integral. The method is tested numerically with known solutions. The integral equatlon model is also applied to actual terrain profiles at four frequencies (144,435, WO, 19oQ MHz), and the results are compared with results from the €lata model and measurements. The standard deviation (STD) of the error is a growing function of frequency, from 3 to 9 dB.

strong enhancement of the electric-field values in SC-2 as compared with the ones obtained without the eyeglasses (that is, SC-1). The results obtained from the two scans (corresponding to the left and right eye lines, respectively) are reported in Figure 5. For the right eye (the one closer to the antenna), which is supposed to be positioned about 20 mm from the lens plane, we have measured a field value of 78.3 V/m, corresponding to 2.12 times the value observed without the eyeglasses. The left eye, on the contrary, exhibits a value of 48.4 V/m, which is more than 2.86 times above the value in the absence of eyeglasses. These values are expected to be different from those which can be measured in the real scenario, where the user's head is considered. However, also in this case, we anticipate a field increase in the ocular region, induced by the presence of the eyeglasses with metallic frames. CONCLUSIONThe enhancement induced by metallic eyeglasses on the e.m. field emitted by a cellular telephone has been investigated numerically and experimentally in a simplified scenario, where we neglect any e.m. effect arising from the presence of the user's head tissues. A significant local increase of the electric field has been detected. This can be especially relevant in the eye region, where hazardous situations can be envisaged. ACKNOWLEDGMENTPart of this work has been sponsored by MIUR.

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