enter image description here

Why the back lobes have such a large area??? I think it may be like https://www.cisco.com/c/dam/en/us/products/collateral/wireless/aironet-antennas-accessories/prod_white_paper0900aecd806a1a3e.doc/_jcr_content/renditions/0900aecd806a1a3e_null_null_null_08_07_07-03.jpg this image on the right side figure. That may look normal.

Here's the data from pattern file excel:2 0 0 360 0 -13.31 1 -13.21 2 -12.93 3 -12.46 4 -11.85 5 -11.17 6 -10.50 7 -9.86 8 -9.28 9 -8.75 10 -8.24 11 -7.75 12 -7.26 13 -6.78 14 -6.32 15 -5.90 16 -5.53 17 -5.23 18 -4.99 19 -4.80 20 -4.67 21 -4.57 22 -4.52 23 -4.51 24 -4.53 25 -4.61 26 -4.73 27 -4.90 28 -5.08 29 -5.25 30 -5.34 31 -5.30 32 -5.10 33 -4.78 34 -4.36 35 -3.92 36 -3.50 37 -3.13 38 -2.84 39 -2.61 40 -2.44 41 -2.32 42 -2.24 43 -2.19 44 -2.17 45 -2.17 46 -2.22 47 -2.30 48 -2.43 49 -2.60 50 -2.80 51 -3.04 52 -3.29 53 -3.56 54 -3.85 55 -4.12 56 -4.32 57 -4.36 58 -4.12 59 -3.52 60 -2.58 61 -1.42 62 -0.18 63 1.06 64 2.21 65 3.27 66 4.22 67 5.09 68 5.87 69 6.60 70 7.29 71 7.94 72 8.59 73 9.22 74 9.84 75 10.43 76 11.01 77 11.55 78 12.04 79 12.50 80 12.90 81 13.26 82 13.58 83 13.85 84 14.10 85 14.32 86 14.52 87 14.71 88 14.87 89 15.02 90 15.14 91 15.23 92 15.28 93 15.29 94 15.26 95 15.17 96 15.04 97 14.86 98 14.63 99 14.37 100 14.07 101 13.74 102 13.37 103 12.98 104 12.56 105 12.09 106 11.58 107 11.01

closed as unclear what you're asking by Glenn W9IQ, SDsolar, Scott Earle Jun 29 at 6:11

Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • 5
    It would be helpful if you could describe or depict the antenna from which the plot was made. – Glenn W9IQ Jun 24 at 10:43
  • 5
    Label your axes, please. – mike65535 Jun 24 at 12:50
  • 4
    Please tell us where this information came from - which software generated it, and what the axes mean. I mean I can see that at around 290 centimetres you have about -29 ostriches, but without context it means nothing – Scott Earle Jun 25 at 4:12
  • 3
    well, we see the typical flightless bird catastrophe happening at 355 centimeters, @ScottEarle. It's clear these ostriches were never linearized before being put through the Turbo Encabulator. On a more serious note, Derrick, we all assume the x-Axis is degree, but if it was, the plot doesn't make sense at all, so please answer Glenn's answer, and the first thing to do here is fulfill mike's plea for labels :) – Marcus Müller Jun 25 at 5:29
  • Thank you here is the pattern data ham.stackexchange.com/questions/10495/…. How could I use it in real situation ? I dont know whtere is the begining of 0 degree of H/E pattern. – Derrick Jun 25 at 19:34

Yes, you might find this article on Antenna Patterns and their meaning helpful. In it they provide a diagram showing the typical plot as you would see it drawn; you have already linked to substantially the same image in your question:

Cisco antenna pattern example

You can see that in this case, 0º is the "front" of the antenna, +90º is the left side, -90º/270º is the right side, and ±180º is the back.

I think your question is, "why does my data show a 'main lobe' off to the left side; why is the maximum gain centered around 90º instead of at 0º?"

We cannot answer this question, because you have not told us:

  • how the data was obtained
  • what the data is supposed to represent

You have shown a chart that looks odd if interpreted as a "final" azimuth plan pattern. But:

  • perhaps the data is from a raw collection and has not been centered to the physical antenna?
  • perhaps it is an elevation plane pattern instead? (this seems plausible given the lack of symmetry even if re-centered!)
  • what others are teasing about: perhaps the data isn't from any antenna measurement at all but something else?

We cannot tell since you have not given us any context of where this data came from and what it is documented to represent.

Note also in that article:

The orientation of the actual plot is largely dependent on the orientation of the antenna in the measurement system and that's all there is to it.

You can see this at play if you look at their Yagi example diagrams, where the main lobe is recorded at 90º rather than 0º.

Interpreting any plot data depends on metadata, i.e. some sort of annotation/documentation with details about how it was gathered and its relative reference. Without that it's not much more than random numbers.


By the way, here's an example of an elevation pattern from the same article. Because of ground plane effects, the pattern is not so symmetrical:

Cisco elevation diagram example

  • Thank you so much!!!! yes!! Now I understand that the 0 degree is the from of the antenna!!! I got the pattern excel data from a datasheet I list some above. Here's the link for the file:galtronics.com/extent-d5777i . I am confused about the 90 degree now and the sequences of numbers above especially the highlight meanings. – Derrick Jun 29 at 2:09
  • Is it possible that because my antenna is directional antenna ??? – Derrick Jun 29 at 2:33

Not the answer you're looking for? Browse other questions tagged or ask your own question.