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Although in normal use the boom member 14 will be quite long, it has been found that the takeoff angle of the signal at maximum strength tilts upwardly more as the first conductor 14 decreases in length from one-half of the wavelength on which the antenna is intended to operate. Stated another way, the first conductor 14 should preferably project beyond level B a distance at least equal to about the length of conductors l6 and 18. When the length of the first conductor 14 is so dimensioned, the takeoff angle at maximum signal strength is optimized for such as CB use and the like. It will be apparent, however, that where a steeper takeoff angle at maximum strength is to be desired in other environments, the length of conductor 14 may be reduced.
It will be observed that conductors 16 and 18 flare outwardly and downwardly. Their relative diameters and the spacing of them from each other and from the mast, as well as the flare, controls the impedance at c, d (FIG. This impedance preferably is 50 ohms in accordance with the typical construction described and for CB use. However, the diameters of the parts, the spacing and the flare may be varied to obtain either different impedances or the same impedance via variance of diameters, spacing and flare in a manner that will be understood by those skilled in the art for the antenna to operate most efficiently.
It has been found, however, that the flare affects not only the impedance, but also influences the takeoff angle at maximum signal strength. The flare of the construction descrihed hereinafter provides a takeoff angle that is about the maximum reasonably allowable for most efficient CB use of this antenna. When the flare was omitted and the conductors 16 and 18 were tested parallel to the first conductor 14 it was found that the takeoff angle at maximum signal strength was as much as to below the horizontal. Although for certain uses, such a downward tilt may be desirable, it appears that the optimum disposition of conductors l6 and 18 lies between the parallel positioning of straight conductors 16 and 18 and the flared positioning of flared conductors 16 and 18 with respect to the conductor 14, as described in conjunction with the specific embodiment illustrated in the drawings.
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