Select a Wi-Fi adapter. Antenna for strengthening WI-FI signal based on a Chinese adapter Wireless connection speed

Take a mesh colander. It's best to use an Asian "scoop" type cookware (like a wok, but with a mesh), which is used for frying. Its shape is perfect for our purposes and it also comes with a wooden handle!

• You can also use a sieve, steamer, pot lid and lamp shade, provided they are hemispherical in shape and made of metal. Any mesh piece of parabolic shaped metal will do - the larger the better the signal, although this may make installation more difficult.
• For larger options, old parabolic TV antennas or a mesh umbrella frame will do. Although they will give greater signal gain, there may be problems with installation and aerodynamic drag, so a 300mm diameter seems to be the most practical.
• A flexible table lamp leg will allow you to carefully position and direct your antenna.

We assemble the system. Using wire, adhesive tape or hot glue, attach the Wi-Fi adapter and USB extension cable to the plate.

• The adapter must be installed in the center of the dish's "hot spot" - radio signals enter the dish and are reflected to the center a few fingers above its surface.
• The best location for the adapter can be determined through a simple experiment. One method is to cover a plate with aluminum foil to determine how it reflects sunlight - the most illuminated point is the focal point of the plate.
• You may need a small rod to secure the adapter in position.
• Alternative securing methods: Use string tied to the front of the plate in a web pattern, scraped out plastic garden hose fittings, or even chopsticks!

Antenna connection. Connect one end of the USB extension cable (male) to your computer, and in the network settings, configure it as a Wi-Fi adapter.

If you want to assemble a long-range WiFi antenna, then you should know about some of its features.

The first and simplest: large antennas of 15 or 20 dBi (isotropic decibels) are the maximum power, and there is no need to make them even more powerful.

Here is a clear illustration of how, as the antenna power in dBi increases, its coverage area decreases.

It turns out that as the antenna’s operating distance increases, its coverage area decreases significantly. At home, you will have to constantly catch a narrow band of signal coverage if the WiFi emitter is too powerful. Get up from the couch or lie down on the floor, and the connection will immediately disappear.

That's why home routers have conventional 2 dBi antennas that radiate in all directions - so they are most effective over short distances.

Directed

9 dBi antennas only work in a given direction (directional) - they are useless in a room, they are better used for long-distance communications, in the yard, in the garage next to the house. The directional antenna will need to be adjusted during installation to transmit a clear signal in the desired direction.

Now to the question of carrier frequency. Which antenna will work better at long range, 2.4 or 5 GHz?

Now there are new routers operating at double the frequency of 5 GHz. These routers are still new and are good for high-speed data transfer. But the 5 GHz signal is not very good for long distances, as it fades faster than 2.4 GHz.

Therefore, old 2.4 GHz routers will work better in long-range mode than new high-speed 5 GHz ones.

Drawing of a double homemade biquadrat

The first examples of homemade WiFi signal distributors appeared back in 2005.

The best of them are the biquadrate designs, which provide a gain of up to 11–12 dBi, and the double biquadrate, which has a slightly better result of 14 dBi.

According to usage experience, the biquadrate design is more suitable as a multifunctional emitter. Indeed, the advantage of this antenna is that with the inevitable compression of the radiation field, the signal opening angle remains wide enough to cover the entire area of ​​​​the apartment when installed correctly.

All possible versions of a biquad antenna are easy to implement.

Required Parts

• Metal reflector - a piece of foil-textolite 123x123 mm, a sheet of foil, a CD, a DVD CD, an aluminum lid from a tea can.
• Copper wire with a cross section of 2.5 mm2.
• A piece of coaxial cable, preferably with a characteristic impedance of 50 Ohms.
• Plastic tubes - can be cut from a ballpoint pen, felt-tip pen, marker.
• A little hot glue.
• N-type connector - useful for conveniently connecting an antenna.

For the 2.4 GHz frequency at which the transmitter is planned to be used, the ideal biquadrate size would be 30.5 mm. But still, we are not making a satellite dish, so some deviations in the size of the active element - 30–31 mm - are acceptable.

The issue of wire thickness also needs to be considered carefully. Taking into account the selected frequency of 2.4 GHz, a copper core must be found with a thickness of exactly 1.8 mm (section 2.5 mm2).

From the edge of the wire we measure a distance of 29 mm to the bend.

We make the next bend, checking the outer size of 30–31 mm.

We make the next inward bends at a distance of 29 mm.

We check the most important parameter of the finished biquadrat -31 mm along the center line.

We solder the places for future fastening of the coaxial cable leads.

Reflector

The main task of the iron screen behind the emitter is to reflect electromagnetic waves. Correctly reflected waves will superimpose their amplitudes on the vibrations just released by the active element. The resulting amplifying interference will make it possible to propagate electromagnetic waves as far as possible from the antenna.

To achieve useful interference, the emitter must be positioned at a distance that is a multiple of a quarter of the wavelength from the reflector.

Distance from emitter to reflector for biquad and double biquad antennas we find lambda / 10 - determined by the features of this design / 4.

Lambda is a wavelength equal to the speed of light in m/s divided by the frequency in Hz.

Wavelength at a frequency of 2.4 GHz is 0.125 m.

Increasing the calculated value five times, we get optimal distance - 15.625 mm.

Reflector size affects the antenna gain in dBi. The optimal screen size for a biquad is 123x123 mm or more, only in this case can a gain of 12 dBi be achieved.

The sizes of CDs and DVDs are clearly not enough for complete reflection, so biquad antennas built on them have a gain of only 8 dBi.

Below is an example of using a tea jar lid as a reflector. The size of such a screen is also not enough, the antenna gain is less than expected.

Reflector shape should only be flat. Also try to find plates that are as smooth as possible. Bends and scratches on the screen lead to the dispersion of high-frequency waves due to disruption of reflection in a given direction.

In the example discussed above, the sides on the lid are clearly unnecessary - they reduce the signal opening angle and create scattered interference.

Once the reflector plate is ready, you have two ways to assemble the emitter on it.

1. Install the copper tube using soldering.

To fix the double biquadrat, it was necessary to additionally make two stands from a ballpoint pen.

1. Secure everything to the plastic tube using hot glue.

We take a plastic box for discs for 25 pieces.

Cut off the central pin, leaving a height of 18 mm.

Use a file or file to cut four slots in the plastic pin.

We align the slots to the same depth

We install the homemade frame on the spindle, check that its edges are at the same height from the bottom of the box - about 16 mm.

Solder the cable leads to the emitter frame.

Taking a glue gun, we attach the CD to the bottom of the plastic box.

We continue to work with a glue gun and fix the emitter frame on the spindle.

We fix the cable on the back of the box with hot glue.

Connecting to a router

Those who have experience can easily solder to the contact pads on the circuit board inside the router.

Otherwise, be careful, thin traces may come off the printed circuit board when heated for a long time with a soldering iron.

You can connect to an already soldered piece of cable from a native antenna via an SMA connector. You shouldn't have any problems purchasing any other N-type RF connector from your local electronics store.

Antenna tests

Tests have shown that an ideal biquad gives a gain of about 11–12 dBi, and this is up to 4 km of directional signal.

The CD antenna gives 8 dBi, since it can pick up a WiFi signal at a distance of 2 km.

Double biquadrate provides 14 dBi - slightly more than 6 km.

The opening angle of antennas with a square emitter is about 60 degrees, which is quite enough for the yard of a private house.

About the range of Wi-Fi antennas

From a native router antenna of 2 dBi, a 2.4 GHz signal of the 802.11n standard can spread over 400 meters within line of sight. Signals of 2.4 GHz, old standards 802.11b, 802.11g, travel worse, having half the range compared to 802.11n.

Considering a WiFi antenna to be an isotropic emitter - an ideal source that distributes electromagnetic energy evenly in all directions, you can be guided by the logarithmic formula for converting dBi to power gain.

Isotropic decibel (dBi) is the antenna gain, determined as the ratio of the amplified electromagnetic signal to its original value multiplied by ten.

AdBi = 10lg(A1/A0)

Conversion of dBi antennas into power gain.

Judging by the table, it is easy to conclude that a directional WiFi transmitter with a maximum permissible power of 20 dBi can distribute a signal over a distance of 25 km in the absence of obstacles.

Please note that some software may be presented in the form of demo versions and have shareware distribution.

Finally, let's make a retreat. One of our customers, having become acquainted with our device, was very surprised by its possible use and wrote to us - you have made equipment for WiFi theft!

Of course, an attacker can use the “WiFi Agent” for illegal purposes. But, with the same success, one can blame the ax sellers for the fact that the new “Raskolnikov” will buy an ax and attack the old money-lender. And dishware sellers are generally accomplices of criminals. There are knives, rolling pins, and a terrible weapon - a cast-iron frying pan.

In light of recent laws, it should be noted that our device does not contain any cryptographic encryption tools and is not a WiFi router. The “WiFi Agent” USB WiFi adapter with a directional antenna does not use any means to hack other people’s networks and does not make the process of “theft” one iota easier than a standard laptop WiFi adapter.

We believe that the issue of using any devices within the law is the direct responsibility of the consumer. Therefore, of course, when performing any action, it is always necessary to remember the legal side of the issue.

We recommend using “WiFi Agent” in situations where the standard WiFi adapter of your laptop or PC receives a low-level WiFi network signal, as well as in cases when you need to use your WiFi network while being at a great distance from the router.

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