M. A. K. Hamid

Microwave Pasteurization of Raw Milk

AbstractA microwave system for the rapid heating of raw milk is described. The effectiveness in bacterial control and potential industrial advantages of the method over the more conventional techniques are illustrated.

Physical Parameters in Microwave Heating Processes

AbstractThe physical parameters involved in microwave heating processes of heterogeneous materials containing water are considered. On the basis of a general equation, which determines the increase of temperature when the body is exposed to microwave electromagnetic field, we analyze the interaction of the thermal, mechanical, and electromagnetic parameters of the body and the heating process. The analogy with scattering of waves by bodies of various shapes is explored and illustrated analytically for the simple model of a plane wave incident on a half space filled with lossy dielectric.

Control of Grain Insects by Microwave Power

AbstractA method is presented for the detection and control of insects in samples of wheat and flour. Experimental arrangements are described for evaluating the scattering coefficients, dielectric constant and loss tangent of wheat and flour at 10 GHz. These results are presented in graphical form and used in the design of equipment for testing penetration and mortality at 2.45 GHz. It is shown that the moisture content in wheat drops by less than l% for exposure times greater than that corresponding to total mortality of three common types of wheat insects (Tribolium confusum, Sitophilus granarius and Cryptolestes ferrugineus). Finally it is concluded that the illumination of bulk wheat by micro-wave power is not adequate for practical treatment unless the infested wheat is circulated in a region of high electric field.

Comparison of Microwave and Dielectric Heating Systems for the Control of Moisture Content and Insect Infestations of Grain

AbstractThe design, operation, and costs of a microwave and a dielectric heating system for the control of moisture content and insect infestations of grain are compared. It is shown that these two novel systems are highly efficient with marginal advantages over each other and significant advantages over conventional hot air dryers.

Microwave irradiation of Potato-Waste Water*

AbstractPreliminary experiments designed to investigate the sterilization of polluted potato-waste water suggest that microwaves may stimulate the growth of aerobic bacteria, which have a high oxygen demand, and may on the other hand reduce the number of photosynthetic bacteria. These observations have yet to be confirmed with further experimentation as the study continues.

The Effect of Microwave Radiation on the Growth and Reproduction of Chickens

AbstractPreliminary results of an experiment designed to study the behaviour of chickens continuously exposed to microwave radiation show no adverse effect on the laying rate, feed efficiency, height of peak production, albumen quality, shell thickness, fertility, hatchability, water consumption, and mortality. The data suggest that, under the experimental conditions described, continuous microwave radiation might have some beneficial effects on chickens. These effects are being explored further as the study continues.

Microwave and High Frequency Applications of Polyconductors

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.

An Iterative Solution for the Reflection Coefficient of a Flanged Waveguide Antenna

Schwarzs 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 Greens 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.

Microwave Test Chamber for Measuring the Relative Permittivity of Thin Dielectric Films

A microwave test chamber for measuring the dielectric constant of thin films on substrates using the cavity perturbation technique is described, Special emphasis is placed on testing biochemical ph...