A Curtain Going Up
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John Schultz W2EEYj l 40 Rossie Stree t Mystic, Conn. 06355 A Curtain Going Up Builcl an easy-to-construct curtain array ancl work that DX! Many amateurs who have the space to erect be effective. However, even small curtains giv an elevated 40 meter dipole can improve the ing only moderate gain can, under the right performance of their antenna system on sev circumstances, be an ideal amateur antenna eral bands and at minimum cost by erecting for fixed direction work. Assuming some sort a small curtain-type array. The advantages of of natural support, such as trees, are available, curtain arrays in general are discussed and sev the only investment is in wire and insulators. eral construction hints are given as worked out Most curtain designs can be used on two or by the author while constructing a small Bruce more bands. by using a resonant feed line, and array. the direction of maximum radiation usually I transported my 20 meter beam to my new remains the same on different bands. QTH, but because the house was surrounded by high trees, roof top mounting would not be Curtains vs. long-wire antennas effective. I didn't want to invest in a tower, so Perhaps one reason why curtains, or broad I would have to find another solution to the side arrays in general, are not given too much antenna problem. consideration by amateurs is that when one Perhaps because of my recent association looks at the gain figures for a small curtain as with Radio Free Europe, where a large nurn compared to a long-wire, the additional con ber of modified curtain-type antennas are struction effort hardly seems worthwhile. For used for transmitting. I thought of using this example, compare the gain of an elementary type of antenna. Curtain arrays have a long broadside array (stacked dipole) against a full history of use as commercial DX antennas. wavelength (double Zepp) wire Fig. 1). Both They were extensively used in the 30's for in antennas give the same gain, about 3 dB, but stance, for trans-Atlantic telephone service. the broadside array is certainly more difficult Sterba curtains for transmitting and Bruce to construct and support than a simple length curtains for receiving were normally employed. of wire. However, the gain figure alone is de However, such antennas have never been used ceiving unless one understands how the gain much in the amate ur fie ld because most ama is actually achieved. teurs think that such arrays must be huge to Any directive antenna, from a dipole on up, concentrates radiation in various directions. This concentration or "directivity" takes place r~-"" --, "''I in the horizontal and/or vertical planes. Co linear antennas, such as a long-wire, achieve gain almost solely by horizontal directivity. 101m is a Civil Service Engineer with the u.s. Navy. He has a BEE from Polytechnic Insti Fig. 1. Simple broods.ide and colineor antennas tute of Brooklyn and has written a number of having about the some gain. articles for many radio magazines. " 13 MAGAZINE.