NVIS Antenna Height

Antenna height is critical to force an HF dipole antenna to radiate upward, instead of toward the horizon, to allow the ionosphere to reflect the RF energy back to earth within 30–400 miles (50–650 km) of the originating station.

Table 1. Height of center of antenna
Freq (MHz) λ (m) Min Height (m) Min Height (ft) Max Height (m) Max Height (ft)

1.8000

167

8.3

27.3

41.7

136.7

1.9000

158

7.9

25.9

39.5

129.5

2.0000

150

7.5

24.6

37.5

123.0

3.5000

86

4.3

14.1

21.4

70.3

3.6000

83

4.2

13.7

20.8

68.4

3.7000

81

4.1

13.3

20.3

66.5

3.8000

79

3.9

13.0

19.7

64.8

3.9000

77

3.8

12.6

19.2

63.1

4.0000

75

3.8

12.3

18.8

61.5

5.3320

56

2.8

9.2

14.1

46.1

5.3480

56

2.8

9.2

14.0

46.0

5.3585

56

2.8

9.2

14.0

45.9

5.3730

56

2.8

9.2

14.0

45.8

5.4050

56

2.8

9.1

13.9

45.5

7.0000

43

2.1

7.0

10.7

35.2

7.1000

42

2.1

6.9

10.6

34.7

7.2000

42

2.1

6.8

10.4

34.2

7.3000

41

2.1

6.7

10.3

33.7