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1-LoopAntHome
2-Introduction
3-Characteristics
4-Comparisons
6-Construction
7-Resources
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5 - Loop Antenna Empirical Data
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- The data below was compiled from testing several small loop antenna using an MFJ-259 antenna analyzer.
- The antenna analyzer was set for the approximate middle of the 20 meter and 40 meter HF voice bands.
- The loop antenna was tuned by means of a variable capacitor until the SWR was at or near minimum and the reactive(Z) and resistive(R) impedances were recorded.
- The frequency of the analyzer was varied in steps of 10 or 20 kHz and the SWR, Z and R values were recorded while leaving the loop tuning unchanged.
- Note that with enough capacitance added, the 62 inch loop was able to be tuned for low SWR levels (1.1) at both the 20 and 40 meter bands.
- Despite the small size of these loop antenna, many DX contacts were established with Europe and South America. A small sampling is listed below.
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1.125" Tubing x 35" Diameter Loop @ 20m (phone band only) Antenna Analyzer Data
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Frequency (MHz)
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14.150
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14.160
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14.170
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14.180
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14.190
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14.200
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14.210
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14.220
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14.230
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14.240
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14.250
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14.260
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14.270
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14.280
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14.290
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14.300
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14.310
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14.320
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14.330
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14.340
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14.350
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SWR
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4.5
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4.4
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4.3
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4.2
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4.0
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3.7
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3.2
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2.7
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2.0
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1.4
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1.1
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1.5
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2.0
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2.4
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2.9
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3.2
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3.5
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3.8
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4.0
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4.1
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4.2
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Reactive Impedance
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97
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99
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101
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102
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99
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87
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46
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0
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0
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0
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0
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16
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26
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36
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44
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34
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33
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34
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35
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37
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38
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Resistive Impedance
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64
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71
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80
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95
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112
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132
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153
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146
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110
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75
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53
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41
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37
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35
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34
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50
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58
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62
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67
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70
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73
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35" Loop Responce @ 20 meters
Enlarge
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Note that at this size:
- Efficiency = 65%
- Q = 1080
- Calculated BW = 13.2kHz
- Useable BW = 40kHz
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1.125" Tubing x 62" Diameter Loop @ 20m (voice band only) Antenna Analyzer Data
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Frequency (MHz)
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14.150
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14.160
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14.170
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14.180
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14.190
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14.200
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14.210
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14.220
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14.230
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14.240
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14.250
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14.260
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14.270
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14.280
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14.290
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14.300
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14.310
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14.320
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14.330
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14.340
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14.350
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SWR
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4.4
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4.2
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4.0
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3.7
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3.4
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3.0
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2.6
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2.2
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1.8
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1.4
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1.1
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1.2
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1.5
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1.8
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2.2
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2.6
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2.9
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3.2
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3.5
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3.8
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4.0
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Reactive Impedance
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NA
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100
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NA
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NA
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NA
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0
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NA
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28
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24
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15
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1
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9
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15
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24
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NA
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37
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NA
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53
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NA
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3.8
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NA
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Resistive Impedance
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NA
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176
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NA
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NA
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NA
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169
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NA
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107
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82
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64
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49
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42
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39
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37
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NA
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35
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NA
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36
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NA
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38
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NA
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62" Loop Responce @ 20 meters
Enlarge
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Note that at this size:
- Efficiency = 91%
- Q = 316
- Calculated BW = 45.5kHz
- Useable BW = 70kHz
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1.125" Tubing x 62" Diameter Loop @ 40m (voice band only) Antenna Analyzer Data
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Frequency (MHz)
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7.125
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7.140
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7.160
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7.180
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7.200
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7.217
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7.230
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7.250
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7.270
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7.290
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7.310
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7.330
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7.350
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SWR
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7.0
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5.8
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4.0
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2.6
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1.5
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1.1
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1.5
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2.7
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4.0
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5.6
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7.7
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9.1
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10.5
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Reactive Impedance
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43
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38
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31
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21
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8
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6
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0
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50
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91
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114
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109
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99
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91
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Resistive Impedance
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10
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12
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15
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22
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33
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54
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81
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117
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106
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57
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34
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21
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15
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Enlarge
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Note that at this size:
- Efficiency = 48%
- Q = 1,292
- Calculated BW = 5.5kHz
- Useable BW = 45kHz
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Did These Antennas Perform?
Yes They Did!
Sampling of SSB Contacts on 35 inch loop:
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Sampling of SSB Contacts on 62 inch loop:
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Even a relatively small 5/8" tubing loop antenna 34" in diameter got out!
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