Full Wave Loop Dimensions


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 AWG the greater the bandwidth. For example: 12AWG will have a lower SWR (Standing Wave Ratio) over a greater frequency range than 16.

The measurements below are in feet and inches. I have rounded off some of the measurements to ease construction.

A flat top Full Wave Loop has a feed point impedance of about 150 ohms.

The formula for figuring a full wave loop is length = 1005 divided by the frequency in megahertz.

Example for 1.9MHz:
Length of a full wave loop 528.95 feet (It is ok to round up to 529 feet).

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.

Example for RG-11A/U:
Length of quarter wave transformer 92FT. = 251 divided by 1.8 MHz multiplied by .66

One end of the 75 Ohm coax attaches to the antenna (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 end of the continuous piece of wire) and the other end 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 transmitter.

Operating Frequency

Full Wave Loop
Antenna Length

Length of 1/4 Wave
Coax Matching
Transformer
( RG-11A/U )

160 Meters

    

1.8 Mhz.

558' 4"

92 Ft.

1.9 Mhz.

528' 11 3/8"

87' 2 1/4"

2 Mhz.

502" 6"

82' 10"

80 Meters

    

3.5 Mhz.

287' 1 3/4"

47' 4"

3.6 Mhz.

279' 2"

46'

3.7 Mhz.

271' 7 1/2"

44' 9 1/4"

3.8 Mhz.

264' 5 3/4"

43' 7 1/8"

3.9 Mhz.

257' 8 1/4"

42' 5 3/4"

4 Mhz.

251' 3"

41' 5"

60 Meters

    

5.4 Mhz.

186' 1 1/4"

30' 8 1/8"

40 Meters

    

7 Mhz.

143' 6 3/4"

23' 8"

7.1 Mhz.

141' 6 1/2"

23' 4"

7.2 Mhz.

139' 7"

23'

7.3 Mhz.

137' 8"

22' 8 3/8"

30 Meters

    

10.1 Mhz.

99' 6"

16' 4 3/4"

10.15 Mhz.

99'

14' 10"

20 Meters

    

14 Mhz.

71' 9 1/4"

11' 10"

14.1 Mhz.

71' 3 1/4"

11' 9"

14.2 Mhz.

70' 9 1/4"

11' 8"

14.3 Mhz.

70' 3 3/8"

11' 7"

17 Meters

    

18.068 Mhz.

55' 7 1/2"

9' 2"

18.130 Mhz.

55' 5 1/8"

9' 1 9/16"

15 Meters

    

21 Mhz.

47' 10 1/4"

7' 10 5/8"

21.1 Mhz.

47' 7 1/2"

7' 10 3/8"

21.2 Mhz.

47' 4 7/8"

7' 9 3/4"

21.3 Mhz.

47' 2 1/8"

7' 9 3/8"

12 Meters

    

24.890 Mhz.

40' 4 1/2"

6' 7 7/8"

24.950 Mhz.

40' 3 5/8"

6' 7 5/8"

10 Meters

    

28 Mhz.

35' 10 13/16"

5' 11"

28.5 Mhz.

35' 3 1/8"

5' 9 3/4"

29 Mhz.

34' 7 7/8"

5' 8 1/2"

29.5 Mhz.

34' 0 3/4"

5' 7 3/8"