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This paper presents descriptive and flight-test information relating to a new type Z-marker antenna system which possesses a number of marked advantages and improvements over that used at present Z markers. The antenna consists of two spaced-dipole arrays, crossed at right angles to each other, and excited in quadrature time phase. The design of the arrays is based on the principle of proportioning dipole currents in accordance with the coefficients of the successive terms of the binomial expansion. The antenna is of simple and rugged design, capable of maintaining a high degree of marker-zone stability under rain, snow, and sleet conditions, and lending itself to prefabrication in units and sections of transmission line for ease in field installation. The marker zone is considerably narrower than the zone provided by present Z markers and is ideally suited to instrument approaches. Whereas the height of present Z markers is limited to about 10,000 feet, the new marker antenna may readily be extended to over 20,000 feet altitude with present transmitting equipment. Pilots have, heretofore, noted the apparent excessive broadening of the marker zone during flights off-course or on flights over the radio range at a large crab angle. This effect, is greatly reduced with the new antenna, making it possible for the pilot to obtain a more accurate fix on the range station.