Cantenna Testing

I was member of Melbourne Wireless for some time while I lived in Abbotsford (node CIA).

During this time I tested the beam pattern of a Harris Coffee Tin used as a circular waveguide. The polar plot below summarises the results. Essentially, the device under test, a harris coffee can of internal diameter 98mm, with a tuned 1/4 (28mm of copper instead of 31mm) wave stub was placed on a post and rotated in an anechoic chamber. From about 8m away, a series of measurements of received signal power were taken by a spectrum analyser. A signal generator was used to launch a constant 10dBm at 2.462 GHz (choice of frequency is a long story, I’ve now forgotten) through a source at the device under test. The directivity or gain of this cantenna is found to be between 6 and 7dBi. I did intend at that time to make modifications and perform further testing to determine the improvement gained by adding an extra length of can to make it 5/4 guide wavelengths long; a choke; a spreader. It’s been some years since I’ve had access to the equipment and the chamber though, in fact I think with the movement of Telstra’s research laboratory team into the CBD, it is likely the facility no longer exists.

Network Architecture

I also did some thinking at that time about feasible ways to construct a network architecture to provide some degree of mesh routing for the wireless community of Melbourne. There are slides to document the design thoughts (also in PPT format.)

Test Result Overview

Gain approximately 6.5dB in a quite symmetric lobe.

At 2.462 GHz

At 2.462 GHz

 

Detailed Test Results

Recorded by: Roger Venning
Date: ########
Frequency: 2.462GHz
Device under test: Cantenna no. 1
Equipment: Signal generator: 10dBm output power. <src?>.  Measurements with Spectrum analyser.
Seems that you would expect to receive -44dBm from an isotropic radiator with this setup.
Azimuth Magnitude – dBm (Azimuth) Magnitude (mW) Normalised gain (azimuth) Elevation Magnitude – dBm (Elevation) Magnitude (mW) Normalised gain (elevation) mean (mW) Average normalised gain
0 -37.15 1.90E-04 7.1 0 -37.8 1.70E-04 6.4 1.80E-04 6.8
5 -37.22 1.90E-04 7 5 -37.71 1.70E-04 6.5 1.80E-04 6.8
10 -37.45 1.80E-04 6.8 10 -37.8 1.70E-04 6.4 1.70E-04 6.6
15 -37.83 1.60E-04 6.4 15 -38.01 1.60E-04 6.2 1.60E-04 6.3
20 -38.31 1.50E-04 5.9 20 -38.38 1.50E-04 5.9 1.50E-04 5.9
25 -38.92 1.30E-04 5.3 25 -38.9 1.30E-04 5.3 1.30E-04 5.3
30 -39.6 1.10E-04 4.6 30 -39.53 1.10E-04 4.7 1.10E-04 4.7
35 -40.34 9.20E-05 3.9 35 -40.34 9.20E-05 3.9 9.20E-05 3.9 3dB
40 -41.27 7.50E-05 3 40 -41.3 7.40E-05 2.9 7.40E-05 3
45 -42.31 5.90E-05 1.9 45 -42.36 5.80E-05 1.9 5.80E-05 1.9
50 -43.29 4.70E-05 1 50 -43.45 4.50E-05 0.8 4.60E-05 0.9
55 -44.44 3.60E-05 -0.2 55 -44.42 3.60E-05 -0.2 3.60E-05 -0.2
60 -45.82 2.60E-05 -1.6 60 -45.29 3.00E-05 -1 2.80E-05 -1.3
65 -47.37 1.80E-05 -3.1 65 -46 2.50E-05 -1.8 2.20E-05 -2.4
70 -48.65 1.40E-05 -4.4 70 -46.61 2.20E-05 -2.4 1.80E-05 -3.3
75 -49.84 1.00E-05 -5.6 75 -47.65 1.70E-05 -3.4 1.40E-05 -4.4
80 -51.13 7.70E-06 -6.9 80 -49.17 1.20E-05 -4.9 9.90E-06 -5.8
85 -52.62 5.50E-06 -8.4 85 -50.17 9.60E-06 -5.9 7.50E-06 -7
90 -53.99 4.00E-06 -9.7 90 -50.24 9.50E-06 -6 6.70E-06 -7.5
95 -55.28 3.00E-06 -11 95 -50.74 8.40E-06 -6.5 5.70E-06 -8.2
100 -56.4 2.30E-06 -12.2 100 -52.86 5.20E-06 -8.6 3.70E-06 -10
105 -57.5 1.80E-06 -13.3 105 -55.45 2.90E-06 -11.2 2.30E-06 -12.1
110 -58.61 1.40E-06 -14.4 110 -55.09 3.10E-06 -10.8 2.20E-06 -12.3
115 -59.19 1.20E-06 -14.9 115 -54.34 3.70E-06 -10.1 2.40E-06 -11.9
120 -59.52 1.10E-06 -15.3 120 -55.59 2.80E-06 -11.3 1.90E-06 -12.9
125 -59.66 1.10E-06 -15.4 125 -57.6 1.70E-06 -13.4 1.40E-06 -14.3
130 -59.54 1.10E-06 -15.3 130 -56.72 2.10E-06 -12.5 1.60E-06 -13.7
135 -59.59 1.10E-06 -15.3 135 -54.76 3.30E-06 -10.5 2.20E-06 -12.3
140 -60.12 9.70E-07 -15.9 140 -54.2 3.80E-06 -10 2.40E-06 -12
145 -61.1 7.80E-07 -16.9 145 -55.68 2.70E-06 -11.4 1.70E-06 -13.4
150 -62.31 5.90E-07 -18.1 150 -59.96 1.00E-06 -15.7 8.00E-07 -16.7
155 -63.3 4.70E-07 -19.1 155 -64.9 3.20E-07 -20.7 4.00E-07 -19.8
160 -62.13 6.10E-07 -17.9 160 -67 2.00E-07 -22.8 4.10E-07 -19.7
165 -59.57 1.10E-06 -15.3 165 -61 7.90E-07 -16.8 9.50E-07 -16
170 -57.36 1.80E-06 -13.1 170 -58.34 1.50E-06 -14.1 1.70E-06 -13.6
175 -56.12 2.40E-06 -11.9 175 -57.05 2.00E-06 -12.8 2.20E-06 -12.3
180 -55.8 2.60E-06 -11.6 180 -57.16 1.90E-06 -12.9 2.30E-06 -12.2
185 -56.14 2.40E-06 -11.9 185 -59.29 1.20E-06 -15 1.80E-06 -13.2
190 -56.95 2.00E-06 -12.7 190 -62.36 5.80E-07 -18.1 1.30E-06 -14.6
195 -58.25 1.50E-06 -14 195 -60.24 9.50E-07 -16 1.20E-06 -14.9
200 -60.25 9.40E-07 -16 200 -55.6 2.80E-06 -11.4 1.80E-06 -13.1
205 -62.6 5.50E-07 -18.4 205 -52.79 5.30E-06 -8.5 2.90E-06 -11.1
210 -64.04 3.90E-07 -19.8 210 -51.45 7.20E-06 -7.2 3.80E-06 -10
215 -63.42 4.50E-07 -19.2 215 -51.29 7.40E-06 -7 3.90E-06 -9.8
220 -61.7 6.80E-07 -17.5 220 -51.86 6.50E-06 -7.6 3.60E-06 -10.2
225 -60.49 8.90E-07 -16.2 225 -52.69 5.40E-06 -8.4 3.10E-06 -10.8
230 -59.7 1.10E-06 -15.5 230 -53.5 4.50E-06 -9.3 2.80E-06 -11.3
235 -58.9 1.30E-06 -14.7 235 -53.5 4.50E-06 -9.3 2.90E-06 -11.2
240 -58.6 1.40E-06 -14.4 240 -53.59 4.40E-06 -9.3 2.90E-06 -11.2
245 -58.8 1.30E-06 -14.6 245 -55.35 2.90E-06 -11.1 2.10E-06 -12.5
250 -58.58 1.40E-06 -14.3 250 -57.05 2.00E-06 -12.8 1.70E-06 -13.5
255 -57.6 1.70E-06 -13.4 255 -54.53 3.50E-06 -10.3 2.60E-06 -11.6
260 -56.33 2.30E-06 -12.1 260 -52.44 5.70E-06 -8.2 4.00E-06 -9.7
265 -55.61 2.70E-06 -11.4 265 -51.86 6.50E-06 -7.6 4.60E-06 -9.1
270 -55.15 3.10E-06 -10.9 270 -51.93 6.40E-06 -7.7 4.70E-06 -9
275 -53.73 4.20E-06 -9.5 275 -51.77 6.70E-06 -7.5 5.40E-06 -8.4
280 -51.84 6.50E-06 -7.6 280 -51.29 7.40E-06 -7 7.00E-06 -7.3
285 -50.15 9.70E-06 -5.9 285 -50.67 8.60E-06 -6.4 9.10E-06 -6.2
290 -48.68 1.40E-05 -4.4 290 -50.03 9.90E-06 -5.8 1.20E-05 -5.1
295 -47.3 1.90E-05 -3.1 295 -48.82 1.30E-05 -4.6 1.60E-05 -3.8
300 -46.12 2.40E-05 -1.9 300 -47.37 1.80E-05 -3.1 2.10E-05 -2.5
305 -45.2 3.00E-05 -1 305 -45.98 2.50E-05 -1.7 2.80E-05 -1.3
310 -44.18 3.80E-05 0.1 310 -44.89 3.20E-05 -0.6 3.50E-05 -0.3
315 -42.98 5.00E-05 1.3 315 -43.93 4.00E-05 0.3 4.50E-05 0.8
320 -41.73 6.70E-05 2.5 320 -42.98 5.00E-05 1.3 5.90E-05 1.9
325 -40.64 8.60E-05 3.6 325 -41.99 6.30E-05 2.3 7.50E-05 3
330 -39.77 1.10E-04 4.5 330 -41.08 7.80E-05 3.2 9.20E-05 3.9 3dB
335 -39 1.30E-04 5.2 335 -40.17 9.60E-05 4.1 1.10E-04 4.7
340 -38.36 1.50E-04 5.9 340 -39.39 1.20E-04 4.9 1.30E-04 5.4
345 -37.85 1.60E-04 6.4 345 -38.79 1.30E-04 5.5 1.50E-04 5.9
350 -37.48 1.80E-04 6.8 350 -38.31 1.50E-04 5.9 1.60E-04 6.4
355 -37.22 1.90E-04 7 355 -38.01 1.60E-04 6.2 1.70E-04 6.6
3.80E-05

Recent Posts

Windows 10 Boot Recovery or Not

I woke on the morn of Good Friday to find the PC at the BIOS screen with a CPU overheat error. Despite the CPU fan being listed as spinning at 1800RPM, the CPU was cooking along at 75deg or so..

Time for a shutdown and vacuum out the dust. Something I’ve done routinely in the past, but this time it all went wrong. On starting the system again…. it didn’t.

After an extremely frustrating sequence of reboots, BIOS setting review, recovery USB key creation I think what happened was that I managed to clear the motherboard BIOS settings. Given that my boot disk was still a pair of Seagate Barracuda’s in Intel RAID1 (mirror), I think that this also was the primary cause of my subsequent inability to boot. That I had installed a SSD for Windows 10 system when I did a clean install (after the original Win7 to Win10 upgrade), was a cause of additional confusion.

Additional complications included building a windows system restore USB key (on another Win10 system), and trying to use the startup repair (available under system recovery menu). Also I think at some point I ran a Linux install-mbr utility. I also ran

bootsect /nt60 ALL / force
bootrec /fixbmbr
bootrec /fixboot
bootsec /scanos
bootrec /rebuildbcd

The RAID pair were an original MBR partion table, and the new SSD a GPT. From a hardware perspective the Asus P8P67 Pro included a 6Gbps SATA Marvel 9120 interface that I am fairly certain are addressable by UEFI BIOS, but not in the early start sequence of the Win10 kernel boot.

Finally, by the time all this had been tried, I ended up with an SSD that had a Microsoft Reserved Partition (16MB), an EFI system partition that was in fact relabelled data partition with my Win10 system in it (200GB or so), and a Recovery partition (500MB or so). At this stage, bootsect /scanos was no longer finding the Windows system install, although in some circumstances is it was located in a path like /?/Volume3/….

So how did I ultimately resolve?

  1. Made the decision to get the SSD bootable and abandon the RAID pair to start.
  2. Rebuilt the partitions on the SSD broadly following this with
    1. boot from windows recovery and run command prompt
    2. diskpart
    3. list disk
    4. select disk X
    5. list partition
    6. select partition 2 (the "EFI" partition that wasn't)
    7. setid EBD0A0A2-B9E5-4433-87C0-68B6B72699C7
    8. shrink desired=200
    9. create partition EFI size=200
    10. format quick fs=fat32 label="System"
    11. exit
    12. bootrec /fixboot
    13. bcdboot c:\windows /s b: /f ALL
      1. (Or maybe I ran bootrec /rebuildbcd later.Initially the fact that I was still plugged into the Marvell SATA meant that step (M) was failing).

 

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