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The RF characteristics of a four-element diagonal array configured to yield low sidelobes, dual circular polarization with low axial ratio and high front-to-back ratio are described. The array was designed for use as source antenna in a VHF test range, where the test antenna is nearly omnidirectional and ground multipath effects are a major problem. To achieve broadband performance, crossed open-sleeve dipoles were used as array elements. The array is capable of operation over a 1.66:1 band with a VSWR of <2:1. Experimental studies were made by means of scale model antennas in the 240 to 400 MHz band. The axial ratio is <1 dB, and the sidelobe/backlobe levels vary from –25 dB to –30 dB over the measurement frequency range.
Antennas are an integral part of the communications, navigation, EMC systems installed on aircraft. Aircraft, such as the Douglas DC-9, C-9A, C-9B, DC-10, KC-10A, A-3 and A-4, use approximately 20 antennas. These antennas operate from VLF to approximately 20 GHz. The radiation patterns of these antennas are affected by aircraft structure such as wings, vertical stabilizer, engines, and landing gear. Douglas Aircraft Company measures the radiation patterns of these antennas using scale model aircraft (and/or aircraft sections) to predict the performance of the associated system. This paper describes some of the scale model measurement techniques used by Douglas Aircraft Company to obtain scale model radiation pattern data.
This paper discusses some of the more unique problems involved in the performance of measurements on a ground plane type of antenna range generally required for the study and design of multiple antenna shipboard systems. The discussion concentrates on the installation and use of a computer automated antenna analyzer system on this type of range. The methods and results of various range calibration measurements are presented with emphasis on the use of the system’s computerized capability to perform measurements, analyze data, and produce various graphic output formats. The test results obtained from a pair of monopole antennas mounted on a simplified model ship hull are also presented and discussed.