Abstract: A spiral antenna (100) having a feed-point end and a termination end for use within a portable two-way radio housing includes a ground substrate (102) and a number of spiral elements (103, 105) having a number of segments that form two or more spiral shapes. A shorting stub (107) connects the planar elements at a termination end for effectively increasing the feed-point impedance of the spiral antenna (100). The spiral elements (103, 105) may be positioned in a planar arrangement (FIGS. 1 and 2) or may be stacked in separate planes (FIGS. 3 and 4) for forming a limited space antenna having a substantially 50 ohm feed-point end impedance at resonance.

Abstract: Heat pipes are employed to capture energy normally lost in the form of heat in the gases in flue-stacks and to transfer the captured heat to water in a water jacket. The heated water is pumped from the water jacket to a storage tank where it is kept until needed. Control of the system is governed by heat sensors in the flue-stack and in the storage tank which provide control signals to a pump, or pumps, used in controlling the flow of water through the pipes between the water jacket and the storage tank.