AN ANECHOIC CHAMBER BUILT INTO INDUSTRIAL ROOMS

The issues of designing anechoic chambers for antenna measurements of a certain type – em-bedded in the premises of industrial purpose are considered. The advantage of such chambers is a positive economic effect associated with both the reduction of costs for construction work, and with the possibility of joint use of auxiliary room systems in the process of operation. Known ap-proaches to the design of chambers for antenna measurements are based either on ensuring a min-imum level of aesthetics, or minimum overall dimensions. In this case, it is necessary to provide a compromise between the parameters of anechoic stability and overall dimensions while ensuring the technological accessibility of the entire usable area of the room. Aim. The aim of the work is to justify the form and geometric dimensions of the chamber. Research Methods. In the process of re-search used the methods of geometric optics. When justifying the form of the chamber, practical aspects were taken into account, namely, the common form of industrial premises and workshops, as well as the possibility of effective use of common radio-absorbing materials to cover the cham-ber from the inside. In the process of finding the optimal effective geometric dimensions, the quality functionals were assumed to be aechoic and dimensional parameters. Results. A chamber in the form of a rectangular trapezoid is optimal for embedding in industrial premises. The expressions for the geometric dimensions of the chamber, ensuring the absence of first- and second-order reflections in the working area, have been found. The optimum value of the deflection angle of the back wall of the anechoic chamber was found. Conclusion. Based on the above technique, an anechoic chamber of a compact range for antenna measurements has been realized.

Causal variational principles in the σ-locally compact setting: Existence of minimizers

We prove the existence of minimizers of causal variational principles on second countable, locally compact Hausdorff spaces. Moreover, the corresponding Euler–Lagrange equations are derived. The method is to first prove the existence of minimizers of the causal variational principle restricted to compact subsets for a lower semi-continuous Lagrangian. Exhausting the underlying topological space by compact subsets and rescaling the corresponding minimizers, we obtain a sequence which converges vaguely to a regular Borel measure of possibly infinite total volume. It is shown that, for continuous Lagrangians of compact range, this measure solves the Euler–Lagrange equations. Furthermore, we prove that the constructed measure is a minimizer under variations of compact support. Under additional assumptions, it is proven that this measure is a minimizer under variations of finite volume. We finally extend our results to continuous Lagrangians decaying in entropy.