[EXPERIMENT] Do parabolic antennae made from Diet Coke cans increase WiFi download speeds? – September 2008

PURPOSE

This entry serves as the record for an experiment that I performed on my wireless network in September 2008. I designed two parabolic antennae from a Diet Coke can and cardboard.

The purpose of the experiment was to see if these antennae would increase the download and upload speeds of my Internet connection per WiFi channel when the parabolic antennae were directed at the test machine.

My hypothesis is that the download and upload speeds per channel will be faster when the parabolic antennae are attached to the router’s antennae because the wireless signal will be directed towards the laptop as opposed to being radiated 360 degrees from the router’s antennae.

PROCEDURE

I used SpeedTest to calculate the download and upload speeds as well as the ‘ping’ response times on each channel (1 through 11) of my wireless connection. (Please see speedtest.net for more information how the tests are performed.)

As for the setup, I had a Westell Versalink 327W hooked up to a Windows XP PC. I ran the speed tests on my Dell D620 laptop running Windows XP using the Windows built-in wireless network connection software. The test laptop was located in Vero Beach, FL (32963). No other connections were being made other than those to a server in Orlando, FL (orl-speedtest.fdn.com). While SpeedTest reported the distance between the laptop and server to be ~100 mi, Google Maps reported the distance from the zip code 32963 to Orlando to be 106 mi, and MapQuest reported the distance from the zip code 32963 to Orlando to be 107.25 mi, so I used a distance of 107 mi as the “official” distance metric (the rounded average of Google’s and MapQuest’s distance metrics).

The path from the router to the laptop was separated by a 4” wall. The distance from router to wall was 11’1” and the distance from the other side of the wall to the laptop was another 11’1”, totaling 22’6” between the router and laptop. There was a 5.8 GHz telephone base station with two phones as well as a cell phone in the same room as the laptop along with a printer/fax/copier in the same room as the router during the test; however, none of this equipment was being used during testing. For each test on each channel, the signal strength, according to the Windows signal strength indicator, showed five bars with a speed of 54.0 Mbps.

RESULTS

The first test, with the parabolic antennae attached to the router antennae, began September 27, 2008 beginning at 7:45pm, ending around 9:45pm, totaling 2 hours. The second test, without parabolic antennae attached, began on September 28, 2008, beginning at 7:25am, ending around 8:45am, totaling 1 hour 20 minutes. (The longer length of the first test was due to a break that occurred due to dinner.) Each of the two tests included measuring the download and upload speed per the 11 WiFi channels.  Following is a summary of the results (click here for the raw data).

Without the parabolic antennae attached:
Maximum download speed achieved, as an average, was 795.0 kbps on Channel 6
Maximum upload speed achieved, as an average, was 144.8 kbps on Channel 3
Minimum download speed, as an average, was 784.2 kbps on Channel 3
Minimum upload speed, as an average, was 127.4 kbps on Channel 8

With the parabolic antennae attached:
Maximum download speed achieved, as an average, was 811.4 kbps on Channel 4
Maximum upload speed achieved, as an average, was 143.6 kbps on Channel 6
Minimum download speed, as an average, was 748.0 kbps on Channel 1
Minimum upload speed, as an average, was 123.6 kbps on Channel 7

ANALYSIS

It’s interesting to note the higher average download speed with the parabolic antennae attached versus without, while also noting the lower average upload speed with the parabolic antennae attached versus without. It’s also interesting to note that, although Ch 4 with parabolic antennae attached, has the fastest average download speed, its average upload speed is 125.8 kbps, lower than the maximum average upload speed of 143.6kbps. One may also note that, without parabolic antennae attached, Ch 3 has the maximum average upload speed, but also the minimum average download speed.

Per channel, on average, the download speeds were faster with the parabolic antennae attached. There were 3 out of 11 instances where the average download speed per channel was slower with the parabolic antennae attached. Adversely, with the parabolic antennae attached, upload speeds were lower on each channel.

CONCLUSION

Considering the original hypothesis that “the download and upload speeds per channel will be faster when the parabolic antennae are attached to the router’s antennae”, the results show that, per channel, on average, with the parabolic antennae attached, the download speeds were indeed higher, with an average maximum download speed of 811.4 kbps, 16.4 kbps faster than the average maximum download speed without parabolic antennae attached. However, the results shows that, with the parabolic antennae attached, upload speeds are lower on each channel. The average maximum upload speed with parabolic antennae attached was 143.6 kbps, 1.2 kbps slower than without parabolic antennae attached.

Factory-shipped router:

Router with Diet Coke halves attached to antennae:

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