Radio and Electronics Today

A—Designed to send and receive radio messages in trucks, taxis, fire trucks, police cars and civil-defense passenger cars, this lightweight unit can be installed quickly by plugging it into a cigarette-lighter outlet to obtain the necessary six volts for operation. It is available in either a variable or fixed-frequency model and may be operated on various wavelengths. It has a power output of about four watts and -a range of approximately 20 miles. It also may be used on a standard 115-volt 60-cycle a.c. line

Blind Spots in Radio Mystify Science

WHAT is the mysterious force that makes certain spots on the earth’s surface apparently impervious to radio messages? Although about fifty of these “dead” gaps have been charted in North America, and its coastwise waters, no one has found the cause for the “blind” pockets. One of the largest dead gaps is just south of Hudson bay in Canada; another is over the ocean off Atlantic City, while a third is supposed to be in the vicinity of Camden, N. J. Neither does Mexico offer an entirely uninterrupted path to the wireless waves, for somewhere south of that country’s capital a blind spot has been found in the air, and further north, on the border of Texas, there is a gap that defies passage of the wireless.