# Hand Hygiene

## October 17, 2009

### Spider Antenna

Filed under: Uncategorized — gthomas @ 5:22 pm

Here’s the first test from our homemade spider antenna, which is supposed to be relatively angle independent.  It looks like this (scale in cm):

The signal is on the central dipole.  The four other blue protuberances are grounded.

We placed the motes at the two different vertical heights (.1m and .35m) at 4 distance from the vertical axis: .25, .50, .75 and 1.0.  We used a power level of 3 on channel 26.  A boxplot of results is here:

Ideally, the data would show 4 steps, one for each distance.  In particular, we’d like to see a clear difference between .75 and 1.0m.  That would mean that the angle and height of the mote was not very important compared to the distance.  Unfortunately, this was not the case.

At the .25m distance, the extreme angles (near 0 and 180), the RSSI was very low, lower than some responses at the 1.0m distance, not a good sign.

Part of the problem may be that we used a power level of 3.  At 1 m, the data seems much more sporadic (particularly before cleaning out the RSSI values collected with poor LQI values).  However, there is little evidence that this configuration is worth pursuing.

For completion, I’ll through in the complete ANOVA table.  Not surprisingly, with 38,000 data points, everything is significant.

General Linear Model: CleanRSSI versus Distance, Height, Angle

Factor    Type   Levels  Values
Distance  fixed       4  0.25, 0.50, 0.75, 1.00
Height    fixed       2  0.10, 0.35
Angle     fixed      19  0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120,
130, 140, 150, 160, 170, 180

Distance                   3   565573  528580  176193  138899.32  0.000
Height                     1        0     348     348     274.27  0.000
Angle                     18   142783  152032    8446    6658.44  0.000
Distance*Height            3     4669    4109    1370    1079.83  0.000
Distance*Angle            54   291034  294622    5456    4301.13  0.000
Height*Angle              18    73695   75701    4206    3315.43  0.000
Distance*Height*Angle     54   348568  348568    6455    5088.67  0.000
Error                  38105    48336   48336       1
Total                  38256  1474658

S = 1.12628   R-Sq = 96.72%   R-Sq(adj) = 96.71%

## 1 Comment

1. [...] Antenna, HorizontalFull angle-height test – Fully crossed 2 heights, 4 distances, 10 angles.  Power level 3.  Conclusion: [...]

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