New Antenna Measurements With and Without the Shield

Transcription

1 New Antenna Measurements With and Without the Shield Raul Monsalve SESE, Arizona State University August 11, 213

2 2 Description The reflection coefficient of the antenna was measured WITH and WITHOUT the shield on the rooftop of our building. However, it was done at a different spot, where the active panels have no blockages along the line of sight for tens of kilometers. One passive panel is also free of blockage, while the other is pointing in the direction of a 2 m 1 m metal structure approximately 1 m away, and other metal walls about 3 m away and covering a vertical angle of about 15 degrees as viewed from the antenna. As ground plane, three pieces of wire mesh covering a total of 1 12 square feet were used. The antenna was covered by the usual foam box. The plan was to obtain 24 hours of data in each configuration, but sadly the control computer in charge of synchronizing the switching and the data saving presented problems and could not allow to save the desired amount of data. The problem is related to its USB interface used to connect it to the instrumentation. This is already being addressed. Still, it was possible to save 1 and 11 hours of data, without and with shield respectively. A power level of dbm was used for the measurements, along with an averaging of 2 traces. Figures 1 through 5 present a summary of the measurements. Appendices A and B present the time streams and temperature correlation for the case with NO shield. Appendices C and D present equivalent information for the case with the shield on. All the figures and results correspond to data that has been corrected using measurements of the open, short, and match. The conclusion, on page 7, summarizes the findings.

3 3 Summary S 11 [db] without shield with shield frequency [MHz] Figure: 1. Typical traces for the antenna with and without the shield. The response with the shield on is not as flat as expected, and therefore a re-tuning under this condition is necessary. However, for the purposes of estimating the antenna stability it is still useful.

4 Summary 5 45 temperature [ o C] frequency [MHz] magnitude [db] Figure: 2. Stability of antenna WITHOUT the shield. TOP: Air temperature. BOTTOM: Variations of reflection coefficient. The reference trace is the last one of the set. The evolution of the dipole pattern between 12 and 19 MHz is as expected when the antenna goes from hot to cold. One sudden vertical stripe occurs 1.4 hours into the measurement. Other smoother vertical patterns seem to coincide with temperature variations.

5 Summary 5 45 temperature [ o C] frequency [MHz] magnitude [db] Figure: 3. Stability of antenna WITH the shield on. TOP: Air temperature. BOTTOM: Variations of reflection coefficient. The reference trace is the last one of the set. The evolution of the dipole pattern between 12 and 19 MHz is as expected when the antenna goes from hot to cold (not identical to the previous figure since the reference trace is different). One sudden vertical stripe occurs 2.3 hours into the measurement. Other smoother vertical patterns seem to coincide with temperature variations.

6 6 Summary slope (first order) [db/ o C] σ residuals [db] frequency [MHz] Figure: 4. Temperature coefficient of the antenna WITHOUT the shield. At every frequency it is modeled with second-order polynomials (see Appendix B). TOP: Coefficients of the first-order term in the models. BOTTOM: Residuals (1σ) of data relative to the second-order models.

7 Summary slope (first order) [db/ o C] σ residuals [db] frequency [MHz] Figure: 5. Temperature coefficient of the antenna WITH the shield on. At every frequency it is modeled with second-order polynomials (see Appendix D). TOP: Coefficients of the first-order term in the models. BOTTOM: Residuals (1σ) of data relative to the second-order models.

8 8 Conclusion The reflection coefficient of the antenna with and without the shield is smoother than when measuring at the normal location, as expected. The flatness, especially with the shield on, is not as good as when measured in the soccer field some time ago due to the several changes the antenna has undergone. A careful retuning should be enough to recover the expected flatness. The time streams present no jumps, other than unexplained single events (see Appendices A and C). As expected, at frequencies around 11 MHz (reflection coefficient of -2) the antenna is more sensitive. At other frequencies the variations are smoother. However, data were recorded with descending temperature only. It is necessary to complete a longer measurement, including periods with increasing temperature when the antenna undergoes more dramatic changes. The dependence of reflection coefficient on temperature is modeled with second-order polynomials (see Appendix B and D). The first-order coefficients are different between the cases with and without the shield. In frequency, they follow a more regular pattern when the shield is on (see Figure 5 TOP), oscillating between ±.15 db/ C. The residuals of the data after removing the quadratic models are also better with the shield on, with a standard deviation of.1 db across the frequency range (see Figure 5 BOTTOM). These results need to be validated after longer continuous measurements, and a retuning of the antenna.

9 9 APPENDIX A: NO SHIELD - Time Streams

10 1 Appendix A 1 MHz [db] 11 MHz [db] 12 MHz [db] 13 MHz [db] 14 MHz [db] Figure: 6

11 11 Appendix A 15 MHz [db] 16 MHz [db] 17 MHz [db] 18 MHz [db] 19 MHz [db] Figure: 7

12 12 Appendix A 11 MHz [db] 111 MHz [db] 112 MHz [db] 113 MHz [db] 114 MHz [db] Figure: 8

13 13 Appendix A 115 MHz [db] 116 MHz [db] 117 MHz [db] 118 MHz [db] 119 MHz [db] Figure: 9

14 14 Appendix A 12 MHz [db] 121 MHz [db] 122 MHz [db] 123 MHz [db] 124 MHz [db] Figure: 1

15 15 Appendix A 125 MHz [db] 126 MHz [db] 127 MHz [db] 128 MHz [db] 129 MHz [db] Figure: 11

16 16 Appendix A 13 MHz [db] 131 MHz [db] 132 MHz [db] 133 MHz [db] 134 MHz [db] Figure: 12

17 17 Appendix A 135 MHz [db] 136 MHz [db] 137 MHz [db] 138 MHz [db] 139 MHz [db] Figure: 13

18 18 Appendix A 14 MHz [db] 141 MHz [db] 142 MHz [db] 143 MHz [db] 144 MHz [db] Figure: 14

19 19 Appendix A 145 MHz [db] 146 MHz [db] 147 MHz [db] 148 MHz [db] 149 MHz [db] Figure: 15

20 2 Appendix A 15 MHz [db] 151 MHz [db] 152 MHz [db] 153 MHz [db] 154 MHz [db] Figure: 16

21 21 Appendix A 155 MHz [db] 156 MHz [db] 157 MHz [db] 158 MHz [db] 159 MHz [db] Figure: 17

22 22 Appendix A 16 MHz [db] 161 MHz [db] 162 MHz [db] 163 MHz [db] 164 MHz [db] Figure: 18

23 23 Appendix A 165 MHz [db] 166 MHz [db] 167 MHz [db] 168 MHz [db] 169 MHz [db] Figure: 19

24 24 Appendix A 17 MHz [db] 171 MHz [db] 172 MHz [db] 173 MHz [db] 174 MHz [db] Figure: 2

25 25 Appendix A 175 MHz [db] 176 MHz [db] 177 MHz [db] 178 MHz [db] 179 MHz [db] Figure: 21

26 26 Appendix A 18 MHz [db] 181 MHz [db] 182 MHz [db] 183 MHz [db] 184 MHz [db] Figure: 22

27 27 Appendix A 185 MHz [db] 186 MHz [db] 187 MHz [db] 188 MHz [db] 189 MHz [db] Figure: 23

28 28 Appendix A 19 MHz [db] 191 MHz [db] 192 MHz [db] 193 MHz [db] 194 MHz [db] Figure: 24

29 29 Appendix A 195 MHz [db] 196 MHz [db] 197 MHz [db] 198 MHz [db] 199 MHz [db] Figure: 25

30 3 APPENDIX B: NO SHIELD - Temperature Dependence

31 Appendix B MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] Figure: 26

32 Appendix B MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] Figure: 27

33 Appendix B MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] Figure: 28

34 Appendix B MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] Figure: 29

35 Appendix B MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] Figure: 3

36 Appendix B MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] Figure: 31

37 Appendix B MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] Figure: 32

38 Appendix B MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] Figure: 33

39 Appendix B MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] Figure: 34

40 Appendix B MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] Figure: 35

41 Appendix B MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] Figure: 36

42 42 APPENDIX C: WITH SHIELD - Time Streams

43 43 Appendix C 1 MHz [db] 11 MHz [db] 12 MHz [db] 13 MHz [db] 14 MHz [db] Figure: 37

44 44 Appendix C 15 MHz [db] 16 MHz [db] 17 MHz [db] 18 MHz [db] 19 MHz [db] Figure: 38

45 45 Appendix C 11 MHz [db] 111 MHz [db] 112 MHz [db] 113 MHz [db] 114 MHz [db] Figure: 39

46 46 Appendix C 115 MHz [db] 116 MHz [db] 117 MHz [db] 118 MHz [db] 119 MHz [db] Figure: 4

47 47 Appendix C 12 MHz [db] 121 MHz [db] 122 MHz [db] 123 MHz [db] 124 MHz [db] Figure: 41

48 48 Appendix C 125 MHz [db] 126 MHz [db] 127 MHz [db] 128 MHz [db] 129 MHz [db] Figure: 42

49 49 Appendix C 13 MHz [db] 131 MHz [db] 132 MHz [db] 133 MHz [db] 134 MHz [db] Figure: 43

50 5 Appendix C 135 MHz [db] 136 MHz [db] 137 MHz [db] 138 MHz [db] 139 MHz [db] Figure: 44

51 51 Appendix C 14 MHz [db] 141 MHz [db] 142 MHz [db] 143 MHz [db] 144 MHz [db] Figure: 45

52 52 Appendix C 145 MHz [db] 146 MHz [db] 147 MHz [db] 148 MHz [db] 149 MHz [db] Figure: 46

53 53 Appendix C 15 MHz [db] 151 MHz [db] 152 MHz [db] 153 MHz [db] 154 MHz [db] Figure: 47

54 54 Appendix C 155 MHz [db] 156 MHz [db] 157 MHz [db] 158 MHz [db] 159 MHz [db] Figure: 48

55 55 Appendix C 16 MHz [db] 161 MHz [db] 162 MHz [db] 163 MHz [db] 164 MHz [db] Figure: 49

56 56 Appendix C 165 MHz [db] 166 MHz [db] 167 MHz [db] 168 MHz [db] 169 MHz [db] Figure: 5

57 57 Appendix C 17 MHz [db] 171 MHz [db] 172 MHz [db] 173 MHz [db] 174 MHz [db] Figure: 51

58 58 Appendix C 175 MHz [db] 176 MHz [db] 177 MHz [db] 178 MHz [db] 179 MHz [db] Figure: 52

59 59 Appendix C 18 MHz [db] 181 MHz [db] 182 MHz [db] 183 MHz [db] 184 MHz [db] Figure: 53

60 6 Appendix C 185 MHz [db] 186 MHz [db] 187 MHz [db] 188 MHz [db] 189 MHz [db] Figure: 54

61 61 Appendix C 19 MHz [db] 191 MHz [db] 192 MHz [db] 193 MHz [db] 194 MHz [db] Figure: 55

62 62 Appendix C 195 MHz [db] 196 MHz [db] 197 MHz [db] 198 MHz [db] 199 MHz [db] Figure: 56

63 63 APPENDIX D: WITH SHIELD - Temperature Dependence

64 Appendix D MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] Figure: 57

65 Appendix D MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] Figure: 58

66 Appendix D MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] Figure: 59

67 Appendix D MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] Figure: 6

68 Appendix D MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] Figure: 61

69 Appendix D MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] Figure: 62

70 Appendix D MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] Figure: 63

71 Appendix D MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] Figure: 64

72 Appendix D MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] Figure: 65

73 Appendix D MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] Figure: 66

74 Appendix D MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] MHz [db] Figure: 67