Cantenna Designs
Wifi antenna reflector? There are several good reasons to try to increase the intake of your wifi system, or increase the signal from the wireless router in a particular direction.
This article contains the design details for the antenna reflector, which we built with tips and advice from elsewhere on the web. Unfortunately, this did not achieve enough support to achieve the objective of long-distance (200 yards) at the reception, but to increase income, and will be fine for less demanding --objectives.
Wifi Antennas - why are they useful?
With wifi, you usually have one or two small antennas built into the wireless router and antenna built into the notebook PC, or USB dongle. Generally, this is all you need, but sometimes you need something a little better.
For example, at home, if your study is at a distance from the router, you can get a bad signal, or far from home, in the hotel, you can find similar problems.
Its solutionYou can improve the antenna on your PC, or if the home can also improve the antenna on your router. The aim is to make a directional antenna, so it is stronger in the desired direction and weaker in the directions that matter. In the notebook, the antenna is usually built into the panel holding the screen, and there is no way to improve it. So you have to buy a WiFi USB dongle to connect an external antenna. Placing the dongle (the USB cable), you can increaseincome, and installing a larger antenna, you can increase your income. In both cases it may be enough to solve your problem, without worrying about directional aspects.
However, if you have an external antenna, either on a PC or router, you can give directional characteristics with appropriate reflector, which we did, as described below. Another option is to make your own directional antenna from scratch, something that just 'cantenna'. Basically it is a metal can,as a guide for radio waves inside the tower as an antenna. On the Web, there is much discussion about the optimal size for cantenna, with many devotees with Pringles foil-lined canisters.
Our WiFi antenna project
The background of this project lived in a hotel with no wifi, but knowing that about 200 yards away was the restaurant with wifi, for which I could get an access code (that there coffee!).
So the task wasimprove my laptop's income, because the extremely weak signal from the restaurant.
As always, I am a part of the research on the Internet, and discussions with technology-minded friends, Jim and Bill. My first thoughts were to go to cantenna, but seemed to be the most appropriate, where the signal was strong, and cantenna to the nearby interference or elsewhere cantenna was used at both ends (router and PC) to provide the type of pipe for the radiowaves.
However, my task was very weak signal that amplify the signal, so I went with another design that have concentrated light waves on a standard antenna. Where's need only minor improvement of the signal, it appears from the Web, even a flat metal reflector antenna is enough. However, for something more challenging, curved parabolic reflector is needed. Convincing evidence that it was my tech contact Bill (ham radio enthusiast in Ohio)agreed with going parabolic design for what I wanted to do, rather than cantenna.
Antenna Design
Various Web sites have design board, which was all useful. Finally, I decided to buy a WiFi USB dongle, antenna connection and a large external antenna, so-called 'rubber duck' to get the maximum profit for the signal before adding the spotlight. Reflector by aluminum foil glued to cardboard curved structure, which puts theantenna.
To create a structure, I used two types of cards. For curved reflector, I was a card that was hard, but could be bent in an arc, without folding or cracking. I bought a card list used to create the image of a thickness of 1.5 mm (1 / 16). For the three semi-circular support, I wanted that card was strict and not easily bent. For this I used corrugated cardboard packing box, about 3 mm (1 / 8 ").
For the shape of the reflector, I used a ParabolaCalculator freeware program. I gave my desired size in hundredths of mm, ie. Mean = 30000 (ie 300 mm, about 12 "), how the program works only with integers. I wanted the focal length of about 6150 (61.50 mm) to reach the half wavelength at 2.4 GHz (I'm not sure justification but I thought that the reflection would indicate an input signal at the focal point than to disturb him). So I set the depth of 9146 (ie 91.46 mm) to the focal length. This gave afocal distance of the average of 0.2 (I read in one website, which ideally should be the ratio between 0.3 and 0.6, but I wanted to pick up a good average weak signals), the program creates a table of values to draw a template the calculations, graph paper.parabola I also identified focal point, a place where it focuses its spotlight collected signals.
I used graph paper template to mark out and cut out the three supports, drilling holes in each of the contact point.Because it was to fit the rubber duck antenna, which is thinner at the top, I hold less for the highest support. I also went further rectangular strip on the card, except crescent needed to reinforce the structure. I even taped an extra strip along here on each item to be stronger / harder - but feel that this was 'over-engineering'!
Then I cut out the rectangle to be bent back, and spent two weeks is shaping to fit support. Mosttime, I had him trapped in the library, gradually add the book to adapt to a more curved shape. Once in the right shape, I glued the curved back supports the antenna in place to ensure that all lined up. I gave the tape around the lots to ensure that while the dried glue (I used a solvent glue 'EVOSTIK' if the water-glue to the affected card).
The last phase of the adhesive sheet of aluminum foil on the back side of a curved shape, the use of very thinlayer of glue. Finally, I glued 'observation' cards on the top assembly, so I could aim precisely on my distant radio sources.
Tests and results
Adding a reflector significant improvements in some signals, and brought in other signals that were not seen, especially when experimenting with the alignment (horizontal v. vertical) and direction. In fact, it was very sensitive to direction - only a few degrees can make a bigdifference of received signal. I inSSIDer used primarily to measure the signal, which was at hand, since the land as it is a graph, and easier to see what changes you are getting the signal as you experiment.
At home, where I have broadband anyway, I was able to pick up an unsecured wifi system, previously out of reach, and get them on the web. So the conclusion is that the principle is functional tapping into the wifi system outside the normal range. Unfortunately, but the original goal wasachieved, it did not bring the restaurant in a row! I think I was just hoping too much to over 200-yard gap. I thought of making a new spotlight with greater width, but the transmission is a problem, and the thought of the giant antennas from the reception hotel ...
Copyright Michael S Mitchell
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