7-MHz Loop Antenna

  
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The loop may be fed inside the center of one of the vertical sides if vertical polarization is preferred. For horizontal polarization, it can be necessary to feed either in the horizontal sides in the center. Optimum directivity happens at proper angles towards the airplane in the loop, or in much more hassle-free terms, broadside through the loop
7-MHz Loop Antenna - schematic

. One need to try to hang the program from on the market supports which will enable the antenna to radiate the utmost amount in some favored path. The overall length of the wire utilized in a loop is determined in ft in the system 1005/f (MHz). Therefore, for operation at seven. 125 MHz the all round wire length are going to be 141 ft. The matching transformer, an electrical 1/4 G« of 75-G™ coax cable, is often computed by dividing 246 by the operating frequency in MHz, then multiplying that amount by the velocity element from the cable becoming utilised. Therefore, foroperation at 7. 125 MHz, 246/7. 125 MHz = 34. 53 feet. If coax with reliable polyethylene insulation is employed, a velocity issue of 0. 66 have to be employed. Foam-polyethylene coax features a velocity issue of 0. eighty. Assuming RG-59 is utilised, the length of the matching transformer will become 34. 53 (ft). 0. 66 = 22. 79 feet, or 22 ft, 91/2 inches. This same loop antenna may well be used to the 14 and 21-MHz bands



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