KLM's 435-18C Circular Polarized antenna brings ail the row advantages of circular polarity of UHF, for optimized satellite and terrestrial communications.

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Although originally inspired and designed for the Phase III satellite, OSCAR 9, the 18C is finding wide appeal and acceptance among DX'ers, ATV'ers, and the 440-450 FM group. Totally new design and construction techniques were necessary for. the 18C because of the strict electrical requirements for good circularity at UHF frequencies.

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The parasitic elements (3/16" 606.1-T6 rod) pass through the center of the boom in both planes, and are isolated from it with polyethylene insulators and locking snap rings.

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Folded dipoles of 3/8" O.D. tubing are used for the driven elements. These provide excellent bandwidth, and, being looped around the boom, maintain perfect element symmetry.

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Circularity is held within 1dB, 430-440 Mhz and 3dB, 420-450 MHz. Electrically, the 18C has nine elements in the vertical plane and nine in the horizontal.

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Offset between them is 1/4 wavelength. Each dipole has a feed impedance of 50 ohms, and two coaxial baluns are supplied.