. QST . een prop-erly matched to the transmission line in use, the (Continued on page 118) 18 QST for Vertical Multiband Antennas Two Practical Systems with Coax Feed BY L. L. TAYLOR,* W8LVK • The radiation angle from a verticalantenna will be satisfactory for long-distance >vork over alH>ut a 3-to-l fre-quency range if the proper antennalength is used. This article offers a solu-tion to the more difrn-ult problem offeeding such an antenna with <oa\.without excessive loss in the feeder. A LTHortiH tlicrt i.« no simple multiband antenna/\ that provides optimum performance with-^ ^ resp
. QST . een prop-erly matched to the transmission line in use, the (Continued on page 118) 18 QST for Vertical Multiband Antennas Two Practical Systems with Coax Feed BY L. L. TAYLOR,* W8LVK • The radiation angle from a verticalantenna will be satisfactory for long-distance >vork over alH>ut a 3-to-l fre-quency range if the proper antennalength is used. This article offers a solu-tion to the more difrn-ult problem offeeding such an antenna with <oa\.without excessive loss in the feeder. A LTHortiH tlicrt i.« no simple multiband antenna/\ that provides optimum performance with-^ ^ respect to matching a transmission line,systems can be devised which are compromisesand can be made to perform fairly well onseveral bands. This article describes two suchvertical antennas, one of which i)erforms quitewell on the 10-, 11-, 15-, and 2()-meter bands,the other on the 15-, 20-, and 40-meter bands. It is pointed out in The ARRL Antenmi Book^that vertical antennas do not make satisfactory 90 80. SO 100 ISO 200 250 300 millivolts/meter Fig. 1—Vertical-plane field patterns of verticalantennas for several values of antenna height. 1 he fieldintensity is expressed in millivolts per meter at a dis-tance of one mile for one kilowatt input. Perfectly con-ducting ground and zero loss resistance are multiband antennas because their angle of radia-tion increases with frequency. This is true exceptfor the region where the vertical antenna is lessthan wavelength long. Between wavelength long the radiation angle de-creases as frequency increases. This is shown inFig. 1, which is a field-intensity plot in thevertical plane of a vertical antenna for threedifferent frequencies. These curves assume zeroloss resistance in the antenna and a perfectlyconducting ground plane. The actual value ofresistive loss in the antenna will merely shrink *319 Summit St., Granville, Ohio. 1 The ARRL Antenna Book, page 186, 5th edition. 2 J. D. Kraus, Antennas, p
Size: 1649px × 1515px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectradio, bookyear1915
