Um On Tree

Fig. 3. Dimensions of a Double Delta antenna which was tested. Coaxial transmission line can also be used as explained in the test.

27 ft in order to allow simple erection of the antenna via a rope support around a high tree trunk.

The antenna was constructed of ordinary stranded antenna wire with egg insulators attached to wooden stakes, driven in the ground, used to place the two Delta triangles at right angles to each other. Special plexiglass insulators were fabricated to join the wires at the apex of the antenna and at the base where the transmission line is joined to the antenna. Probably many other schemes can be used for these insulators, but the plexiglass types are simple and inexpensive to fabricate. Details of the construction of these insulators is shown in Fig. 4. The upper insulator joins the individual Delta elements in a criss-cross fashion with the non-inductive type terminating resistor mounted on one side of the plexiglass insulator and connected by jumper wires to the Delta elements. A hole was drilled in the center of the insulator and 'A in. nylon rope knotted underneath the insulator for use as a support line. The bottom insulator is basically the same as the upper insulator, except that the jumper wires for the Delta elements

wrmntJiom 1 - 7 7

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