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Antennas to Build
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The measurements below are for building a full wave loop using wire . The wire size may range from 16 AWG to 12 AWG . The lower the wire number the greater the bandwidth . For example 12AWG will have a lower swr ( Standing Wave Ratio ) over a greater frequency range than 16 AWG .
The measurments below are in feet and inches . I have rounded off some of the measurments so it will be easier to measure them .
The diagram below is a representation of a ( Full Wave Loop ) . A flat top has a feed point impedence of about 150 ohms .
The yellow line is a one full wavelength antenna .
The red line ia a representation of a support to hold the antenna above the ground .
The orange center is the representation of the coax connection . The center conductor of the coax connects to one end of the continuous piece of wire , and the shield of the coax connects to the other .
The drawing on the left , is when you feed the loop antenna in the center the antenna takes on a horizontal radiation pattren , but when you feed the antanna in the corner , like the drawing on the right , the antenna takes on a vertical radiation pattreen .
The formula for figuring the quarter wave coax transformer is " length = 251 divided by the frequency in megahertz times the velocity factor of the 75 ohm coax you desire to use .
One end of the coax that attachs to the antenna , and the other end where you install a PL259 connector . From there you may install a barrel connector and any length of 50 ohm coax to get the antenna connected to the tranmitter .