The input admittance of a long hollow conducting cylindrical antenna with an infinitely long dielectric sleeve surrounding it, and excited by a uniform field applied across a gap of a given width at the center, is determined by a variational method. A suitable trial field is chosen and the resulting integrals are evaluated asymptotically with the assumptions that the electrical radius of the antenna is small and its length is large. The final expression is easy to evaluate and some numerical results are presented.

The problem of excitation of the modified Goubau line from a coaxial junction is analyzed using the Wiener‐Hopf technique and Fourier transforms in the axial direction. The analytical expressions reduce to those of Ledeboer in the absence of the air gap. The effects of the air gap in reducing the input reflection coefficient and in modifying such other parameters as the launching efficiency and propagation constants for different frequencies are illustrated with numerical examples.

Ray optical analysis of scattering from a dielectric-coated conducting cylinder using the geometrical theory of diffraction is presented and compared with the leading term of the asymptotic expansion of the exact solutions obtained when the dimensions are electrically large. Schematic representations of the various types of rays undergoing different kinds of interaction between the conducting core and the dielectric layer are given. It is shown that this interaction phenomenon is largely governed by the refractive index of the dielectric and the ratio of diameters of the composite cylinder to that of the conducting cylinder.

The near-field broadside coupling between a pair of two-dimensional H-plane sectoral horns is derived using the method of overlapping regions in conjunction with Schwarz's procedure to solve the resulting integral equations by numerical iterations as well as the generalized scattering matrix technique. The primary advantage of the method is that it allows an arbitrary initial assumption of the aperture field distribution and reasonably corrects it in order to take into account the multiple scattering effects. It is shown that only a few iterations are required for typical coupling geometry and that the number of iterations and the convergence of the series' computations are improved for shorter horns and closer separation distances. Graphical results for the aperture field distributions for specific geometries are presented.

A time-domain technique for the measurement of return loss, attenuation and coupling loss of leaky coaxial cables is described. The technique is based on a simple signal flow graph procedure where the leaky cable is represented by a three-port network, with the third port being introduced to represent the leakage from the cable. The measurement procedure is described, while experimental results for three different leaky coaxial cables are presented and compared with frequency-domain data.

The mode matching technique is employed to solve for the scattering parameters in cross-junction and specially truncated bends in parallel-plate waveguides where the general problem reduces to the solution of three canonical boundary value problems. The basic geometry in all three cases involves a finite wedge region overlapping with a semi-infinite parallel-plate region. The scattering coefficients in each case are determined by matching across the common boundaries the eigenfunctions expansion in each region. Typical results to demonstrate the accuracy of the reflection coefficient and the convergence of the infinite series are presented.

The method of overlapping regions, together with Schwarz's technique, is applied to waveguide discontinuity problems to illustrate its potential and basic advantages and disadvantages over other methods. The method reasonably corrects an arbitrary initial assumption of field distribution in the plane of discontinuity to the final value in a small number of iterations. The advantages are illustrate...

A method for improving the directivity of a dipole antenna of arbitrary length by double impedance loading is investigated. The method of moments is applied to determine the current distribution on the antenna. The directivity as a function of connected load, based on the method of moments, is then developed. The optimum load for maximum directivity is obtained by maximizing the directivity with respect to the connected load. Numerical results for the current distributions and radiation patterns of an antenna when loaded with the optimum load are also included.

A small-sized solid-sate oscillator is designed using a V02 transition metal oxide polyconductor film known as moxie. The oscillator produces an output voltage of 47.5 V with a frequency of about 23 kHz. A theoretical analysis has also been mode of the operation of such oscillators together with the development of the expressions for the output voltage, current and frequency. Calculations based on the properties or polyconductors are presented for such a system. Measurements, which confirm these calculations, are performed with several commercially available polyconductors.

Preliminary tests on small quantities of sand with varying moisture content using a capacitive probe yielded reliable data as to the percentage of moisture. These tests indicate that the design of the monitoring system is feasible, provided that further tests are carried out and that an actual full-scale system be evaluated.

Several applications of V02 polyconductors at microwave frequencies are suggested for monitoring microwave power, switching, detection, protection, noise generations or steady-state oscillation. For these applications the basic microwave properties of VO2 devices or, film are measured to determine the input impedance versus frequency, the input impedance versus power, the scattering cross-section and the signal-to-noise ratio. Specific circuits are also presented to illustrate each typical application of the device.

The boundary-value technique is applied to the general case of a dielectric-coated transmission line with an airgap between the conductor and inner surface of the dielectric. The characteristic equation of such a modified Goubau surface-wave transmission line is derived for the general case of a lossy dielectric and imperfect conductor. This equation is solved leading to expressions for the attenu...

The effect of higher order interactions in the coupling between two H -plane sectoral electromagnetic horns on the field distribution at the aperture of the transmitting horn is calculated using the point matching technique. A nonsingular integral equation for the induced current in the receiving horn, due to the initially incident wave from the transmitting horn, is formulated using a conformal transformation which maps the cross sectional contour of the receiving horn onto two circles on which the induced currents are finite. The solution leads to a modified field distribution in the transmitting aperture which is then employed in Hu's near-zone power transmission formula to compute a gain correction factor for H -plane sectoral horns. It is shown that the correction factor oscillates about that reported by Chu and Semplak with an amplitude which increases for smaller separation distances.

Schwarz's iterative procedure of overlapping regions, which has been previously employed in the solution of polygonal waveguides and similar problems, is employed here to solve for the scattering matrix coefficients at the sharp junction of a sectoral and parallel-plate waveguides. It is shown that by dividing the junction into semi-infinite rectangular and sectoral subregions, and using the Green...

A series of four experiments were conducted to assess the immediate and long-term effects of a single high-wattage input of microwave energy on the day-old chick. The minimal lethal dose of microwave energy input for a day-old chick was established at approximately 88.6 watts/sec over a 9-sec interval or a total of 800 watt-sec (joules). Sublethal radiation at 596 watt-sec (6 sec exposure) caused unconsciousness for up to 5 min and 42% mortality. Survivors showed some cutaneous burns associated with reduced early growth, but from 3 to 40 wk of age there were no effects on growth, mortality or reproduction. Radiation at 392 watt-sec (4 sec exposure) had no immediate or long-term effect on the birds. A safe maximum exposure dose for the day-old chick, of 1 mw/cm2 over 9 sec, is proposed.

Schwarz's iterative procedure of overlapping regions is employed to solve for the reflection coefficient at the open end of a flanged parallel-plate waveguide antenna, with the flange being of arbitrary flare angle. It is shown that by dividing the junction into circular and semi-infinite rectangular and sectoral sub-regions, and using Green's functions of each, the problem is reduced to the solution of a system of integral equations of the Fredholm type. The solution for the reflection coefficient of an H-plane sectoral horn is also obtained as a special case when the flare angle is less than 180° and therefore the rectangular and sectoral sub-regions directly overlap. It is shown that, in addition to being relatively simple and efficient, the solution also leads to geometrical insight into the problem whereby the magnitude of the reflection coefficient is related to the area of the overlapping region.

The scattering cross section of a conducting cylinder coated with a multilayer of homogeneous dielectric due to a plane electromagnetic wave incident at any arbitrary angle is derived by the boundary-value method. The analytical results are treated by Rosenbrock's method to generate optimum radial dielectric profiles corresponding to minimum and maximum backscattering cross sections.