JOVE RJ1.1, Assembly Manual

11

Assembling the Antenna

Measuring and Cutting Wire and Rope

Measure and cut the proper lengths of the bare copper wire, the coaxial cable, and the

rope. A good long hallway is excellent for this job. Use tape on the floor to mark the

lengths for each of the different cuts.

1.

o

Cut 4 sections of the copper wire to 12 ft. 4 in. (3.76 m).

Use the formula for practical antennas and calculate 

λ

/2 length for the wire.

λ

/2 (practical) = 23.28 ft. or 23 ft. 3 in.

Divide by 2 to calculate 

λ

/4

λ

/4 (practical) = 11.64 ft. or 11 ft. 7.7 in.

Subtract 1.5 in. to account for the 3 in. center insulator

λ

/4 (corrected) = 11.52 ft. or 11 ft. 6 in.

Add 5 in. to each end of the wire for wrapping the insulators

Proper Wire Length = 12.35 ft. or 12 ft. 4 in.

2.

o

Cut 2 sections of the coaxial cable to 

λ

/2 = 16.2 ft. (4.94 m)

Use the formula above for the ideal antenna wavelength and calculate 

λ

/2 for the

coaxial cable.

λ

/2 (coax) = 24.48 ft. or 24 ft. 5 in.

Multiply by the velocity factor (V

f

 = 66%) to calculate the proper coax length

λ

/2 (corrected) = 16.15 ft. or 16 ft. 2 in.

3.

o

Cut 1 section of coax to 

λ

 = 32.3 ft. or 32 ft. 4 in. (9.85 m).

Wrapping the Insulators

1.

o

Using the copper wire, thread the extra 5 in. (12.7 cm) through the hole in the

insulators and wrap it back on itself. If necessary use pliers to wrap the wire tight.

2.

o

Wrap the ends of two copper wires around one insulator (center insulator) and

then the other ends around two separate insulators (end insulators). The result should

look like the examples in Figure 2.

3.

o

Repeat this procedure for the second dipole.  A measurement of the total length

of the antenna (from one end insulator to the other end insulator) should be 23 ft. 3 in.

(7.09 m).