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A theoretical and an experimental study of the electromagnetic scattering from a perfectly conducting thin wire of V shape illuminated by a plane wave at an arbitrary incidence is presented. The distribution of current on the wire is first determined by a method of moments with the aid of a computer program WIRANT (developed by Walter L. Curtis of The Boeing Company). The scattered field and backscattering cross section are then obtained by standard techniques. Numerical calculations include the backscattering cross sections for the case of h = \lambda/2 and \lambda (where h is arm length and \lambda is wavelength) as a function of incidence angle \phi with enclosed angle \theta as a parameter. To check the accuracy of the theory, an experiment is conducted inside an anechoic chamber, using the conventional method of cancellation. The frequency used in the experiment is 9.8 GHz. A number of experimental models were constructed of a copper wire of a circular cross section with a diameter d = 0.025". The agreement between theory and experiment is, in general, very good. The results of this investigation provide an insight into the coupling effect between the halves of wire when viewed as two-coupled wires.

The HF antenna on the Boeing 767 AWACS is analyzed by numerical techniques, using a wire mesh model for the entire aircraft. The input impedances are computed and compared with measurements in the frequency range of 2 to 30 MHz. The computations and the measurements are in good agreement. Computations on antenna-to-antenna coupling also are included.

A study of the field distribution in a square aperture on a plane conducting screen illuminated by a plane electromagnetic wave at normal incidence is presented. In solving the problem, the square aperture is first formulated into a complementary square plate scattering problem. The distribution of current on the plate is then found by solving the corresponding wire mesh model with the aid of a computer program for linear wire antennas. A simple averaging process is then introduced in a straightforward manner to convert the currents flowing along the wires into continuously distributed equivalent surface currents on the square plate. The surface current density is, in turn, equal to the value of magnetic field intensity by the boundary condition for a perfect conductor. Finally, a direct application of the electromagnetic form of Babinet's principle gives the electric field distribution of the aperture. The far zone field in terms of a radar cross section of a square plate compares well with an experiment. A discussion is also included comparing the electric field distribution of a square aperture and circular apertures.

A study is presented of the backscattering from two identical, perfectly conducting, thin cylinders illuminated by a plane wave at an arbitrary angle of incidence. The theory is based on an integral equation method. By decomposing the induced currents into symmetric and antisymmetric modes, the simultaneous integral equations for the induced currents are converted into independent integral equations similar to the one for a single cylinder for which the solution has already been carried out. The induced current on the cylinders and the backscattering cross sections of the cylinders are determined. Comparisons are made between the calculated and the measured values of the echo area. The experimental results are in good agreement with theory.

The fundamental transmitting characteristics of an imperfectly conducting circular-loop antenna are investigated theoretically. To obtain the antenna-current distribution, a mathematically simpler method based on a differential equation for the loop current is first developed. Next, an existing, more general method based on an integral equation for the distribution of current is applied with modification and solved numerically with a digital computer. Knowing the current distribution, one can easily find the driving-point impedance. The results of both methods are compared for the case of uniform resistive loading, and they are found to be in good agreement. Some additional numerical examples showing the effect of nonuniform reactive loading on the driving-point impedance are also included. The outcome of this research should provide useful information for the design of broadband circular-loop antennas.