Powerful antenna for a router with your own hands. DIY WiFi antenna: is it possible? Etching a printed circuit board using a solution

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

Antennas at 9 dBi work only in a given direction (directional action) - 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 the 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 dimensions of the biquadrate would be 30.5 mm. But still we don't satellite dish, therefore, some deviations in the dimensions 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 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.

WITH reverse side We fix the boxes with hot melt 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 tracks may come off printed circuit board during long-term heating with a soldering iron.

You can connect to an already soldered piece of cable from a native antenna via an SMA connector. There should be no problem purchasing any other N-type RF connector from your local electronics retailer.

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.

A,dBi	30	20	18	16	15	14	13	12	10	9	6	5	3	2	1
A1/A0	1000	100	≈64	≈40	≈32	≈25	≈20	≈16	10	≈8	≈4	≈3.2	≈2	≈1.6	≈1.26

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.

A WiFi antenna is an excellent solution for anyone who has tried to organize wireless Internet distribution at home or at work, but has encountered the problem that the router signal is not enough to use it without problems in some remote room. However, this is not the fault of your router, but of the antenna - built-in or external, which was included in the package. One of the most effective solutions for strengthening a wireless signal is a directional external wifi antenna. They come in several types and types that are used depending on your needs. And it is precisely this diversity that we will now understand.

External passive antenna for WiFi router

First of all, it should be noted that a passive antenna for wifi router, that is, which does not have its own power supply from the mains, does not amplify the signal, but only directs its spectrum for more reliable reception. The power of this “amplification,” also called directional gain, is measured in decibels (dBi). Many models of routers and adapters are already equipped with small external antennas, but their power does not exceed 3-5 dBi, which will not significantly improve the range of the wireless signal.

Therefore, external wifi antennas are used for this. They have two types of separation - for outdoor or indoor use, as well as omnidirectional and narrow directional.

Outdoor and indoor antenna use

• Outdoor antennas are those that are designed to work outdoors. They are protected from the effects of precipitation and sunlight and have special fastenings for installation on the wall of a building. They will be needed if you want to create a secure reception area in the yard or for communication between neighboring houses.
• Indoor antennas - for indoor use. For example, if your router is installed in a remote or closed place, then such an antenna can be connected with a cable to the antenna connector of the router and brought to the center of the room.

Directional wifi antenna

This is the most used type. An antenna that directs a wifi signal in a certain direction, for example, from a house to a personal plot, or to the balcony of a neighboring house, if we're talking about about external directional wireless antenna. Their range can be from one to several km. The main thing is that the reception source is in direct line of sight.

Internal directional wifi antennas for a router will be useful if, for example, it hangs on the wall. To prevent radiation from reaching the wall, you can connect it to the router and point it towards your desktop on which the laptop is placed. Or vice versa, point the antenna at the partition so that the signal passes through it more confidently, providing stable communication in the next room. A very successful design of such an antenna is a panel rectangle that emits a radio signal in one direction.

Please note that it is connected to the router not via USB, but instead of the attached antenna that came with the router. Accordingly, if it was not removable, then it will not be possible to replace it with another one.

There are also compact models that are suitable for both indoor use and outdoor mounting.

An omnidirectional wifi antenna is distinguished by the fact that it evenly distributes the signal around itself. The disadvantage is that the signal may be distorted by emissions from other electronic devices located in the apartment, or by external radio waves if it is installed outdoors. These antennas look like a vertical rod. External ones can be installed on the roof of the house or on a vertical pole dug into the ground. Internal - on a table or shelf, as close as possible to the expected center of the desired reception area.

The external wifi antenna for the router is attached in the same way in place of the standard one to the same connector.

Another interesting type of indoor omnidirectional wifi antennas is for ceiling mounting. They look like a lamp. Its peculiarity is that there is a dead zone directly under the antenna and it needs to be hung exactly in the place where the signal is not needed, and reliable reception will begin only at a short distance from it.

Installing a WiFi antenna

When installing any type of antenna, it is necessary to consider where the signal source is coming from. In modern urban development, it can greatly lose in efficiency both due to the density of houses and the materials from which they are made. I provide a table from which you can roughly understand how much this or that material degrades the performance of the access point. The most important parameter here will be “Effective distance” (ED). It must be calculated as follows. For example, the characteristics of the router indicate that it operates at 400 meters. it is understood that with direct visibility. You are separated from it by an interior wall with an ER of 15%. We calculate: 400 m multiplied by 15% and we get 60 meters. That is, through a 15-20 cm wall, the router will “shoot” only 60 meters. Moreover, if you attach an antenna of 15-20 decibels to it, this loss will be neutralized.

Homemade wifi antenna with your own hands

You can make a directional Wi-Fi antenna with your own hands. Watch a video on how to make a homemade structure from an ordinary beer can.

I can’t say for sure whether this is true or false - I think there is some reason. By analogy with this popular example, you can also make a directional antenna from an omnidirectional one. To do this, it is enough to attach a reflective screen behind it, for example, from the same sheet of foil. Below are several interesting options for making an antenna with your own hands that you can use.

Option with a tin can as a reflector

That's all for today. You can read about ways to strengthen the signal of a 3G modem in another article on the blog.

It so happened that at work we were left without the Internet, and this served as an incentive to make an antenna. The main criterion was to achieve results with minimum costs. Thus, everything that was at hand was used. And at hand was: two TP-Link Wi-Fi modems, not crooked hands, desire and goal. The distance between potential access points was about 700 meters within line of sight. A standard Wi-Fi modem can only travel up to one hundred meters. To increase the gain, it is necessary to focus the highly directional signal. Ideal for these purposes helix antenna John Kraus for frequencies in the range from 2 to 5 GHz. IN wireless networks, using the IEEE 802.11b standard, also known as Wi-Fi, uses a frequency of 2.43 GHz.

A helical antenna can be described as a spring with a number of turns N with a reflector. The circumference (C) of a turn is approximately the wavelength (l), and the distance (d) between turns is approximately 0.25C. The reflector size (R) is C or l and can be circular or square. The design of the emitting element causes circular polarization (CP), which can be either right- or left-handed (R and L, respectively), depending on how the spiral is wound. In order to transmit maximum energy, both antennas must have the same polarization direction, that is, wound in the same direction.

For these purposes, an ordinary plumbing plastic pipe with an outer diameter of 40 mm is ideal, taking into account a wound copper wire with 1 mm insulation - this is 42 mm (turn diameter). But we assembled the antenna from what was at hand, and we had vinyl plastic rods with an outer diameter of 35 mm on hand. In this case, the coil diameter is 37 mm, which is also not bad.

Calculations

For plastic pipe with a diameter of 40 mm

Coil circumference:

Reflector size (R) 42 not less than C or l – 14 cm.

For vinyl plastic round rod with diameter 35mm

Coil circumference:

For 2.5 km, 12 orbits are sufficient (N=12).

The length of the pipe will be about 40 cm (3.24 l).

Reflector size (R) is not less than C or l – 14 cm.

Necessary materials:

• foil getinax was used for the reflector, but you can also use any copper or aluminum plate of any thickness. But not very thin, because... the reflector is the main carrier base of the antenna;
• single-core copper wire no thinner than 1 mm in diameter (we used a wire with a cross-section of 1.5 square) in PVC insulation about 1.5 m long;
• round core made of vinyl plastic with a diameter of 35 mm and a length of 40 cm;
• a strip of copper foil for making a wave generator in the shape of a triangle. The size of the small leg is 17 mm, the length of the hypotenuse is 71 mm. The thickness is not fixed, the main condition is that it can be wrapped around the core;
• to connect the coaxial cable I used a connector from an old 10 Mbit/s network card;
• the fastenings are arbitrary.

Build process

First, let's take a vinyl core. Let's put markings on it. The distance between the marks, according to our calculations, should be 29 mm. This is the distance between turns. To align the wire, I usually use one not tricky way. Holding one end of the wire in a vice, forcefully pull it into the string by the other end. In order to lay the wire evenly, I drilled a hole at the outermost mark. The diameter of the hole is equal to the diameter of the wire with insulation, which will allow you to fix the end of the wire by inserting it into the hole. Then we wrap the wire tightly around the core. Smoothly stretch the spiral and fix the coils on the marks with glue. The result should be 12 turns with a distance of 29 mm. When using a pipe as a core, a problem arises with attaching the reflector.

There is a need to use additional parts. In our case, the core is made of vinyl plastic. It is easily attached to the reflector using a regular screw - a self-tapping screw, the length of which is about 50 mm. I used a cap screw to make it easier to tighten. To attach the reflector, make a marking for the hole in the center of the plate. We find the center by crossing the diagonals. The diameter of the hole depends on the diameter of the mounting screw. We also measure from the center a distance equal to the radius of the core. Here we drill a hole for the connector. If there is no connector, the coaxial cable can be soldered directly. We solder the shielding contact to the reflector plate, and the central core to the wave generator. The role of a wave generator will be performed by a triangular plate made of copper foil. We solder the tip of our spiral to the thin corner of the generator. The hypotenuse of the copper foil triangle should be a continuation of the spiral.

Since the antenna will be installed outdoors, it is recommended to fill the soldering areas with silicone and put heat shrink with a diameter of 50 mm on the core.

Installation and configuration

I made two identical antennas. One was installed on the roof of a house where there is Internet. The second antenna is installed on the roof of the service building. To achieve maximum effect, both antennas must be pointed at each other and in direct line of sight. Wi-Fi was used as access points TP-LINK modems. Both APs have MOD Point to Point installed indicating the MAC address of the other modem. This setting is set for security reasons in order to cut off unauthorized connections to our network (freeloaders with laptops and smartphones).

If you are not afraid of looters, then I recommend installing a Wi-Fi modem near the antenna. You can attach it to the back of the reflector. Naturally, placing it in an airtight package. The modem is connected to the computer via a twisted pair cable (Ethernet). By shortening the coaxial cable as much as possible, you will reduce signal attenuation. Unfortunately, in the security service of our organization, many are called Alexander Rodionovich Borodach :-)

With the kind permission of Vladimir (VBM), we reprint his description of the design of the FA-20 panel sector antenna, which, despite its simplicity, has proven itself to be highly productive and reliable.

1. Introduction

The original description of the author is located at http://sterr.narod.ru/wifi/fa20.htm. Description from Volodya - http://vbm.lan23.ru/wifi/fa20.html. You can find a lot of positive reviews about this design on the Internet, but it is noted that manufacturing accuracy is very important, especially for vibrators and mounting holes in the reflector. Maintaining the distance between the reflector and the vibrators is also of great importance. Be sure to adhere to the specified dimensions, this will allow you to achieve maximum antenna efficiency.

2. Design

The antenna consists of four structural elements: a reflector (1), two types of vibrators (2, 3) and a connecting bus (4), which serves to connect the vibrators:

3. Materials

To assemble the antenna we will need:

1. Single-sided foil PCB (for reflector)
2. Double-sided foil PCB (for vibrators)
3. Strip of brass or copper foil (for busbar)
4. Aluminum corner 25×25 mm
5. Rivets
6. F connector

4. Manufacturing

First of all, you need to make a reflector “trough”. To do this, according to the drawing, we cut out a rectangle from foil PCB 490×222 mm for the bottom, mark it (it is best to core from the foil side) and drill holes with a diameter of 2.5 mm for the stands for vibrators, tin them. After this, we make sides of the appropriate size from an aluminum corner 25x25 mm, and fasten them with rivets on the back side of the reflector:

Blanks


For accurate marking, it is best to use a caliper


When attaching the corners with rivets, also secure the edges of the corners

After assembling the “trough” of the reflector, you can strengthen it a little by gluing the corners on the back side with mounting tape, and gluing the vertical seams with two-component epoxy glue:

Strengthening the structure

Volodya came up with an original technology for making vibrators from fiberglass, foil-coated on both sides. Advantage this method the fact that from one workpiece two absolutely identical vibrators are obtained.

First, a rectangular blank of the required dimensions is cut out from textolite:

Blank for making vibrators

1. Cut rectangles with metal scissors 1
2. We stratify the fiberglass, we try to stratify halves of the same thickness
3. We make slits along the red lines of the rectangles with 2 ordinary household scissors
4. Take a broken hacksaw blade for metal and cut 2 rectangles along the green lines
5. Using fine sandpaper, carefully clean the ends of the resulting vibrators

Ready-made vibrators

As a result, we get two vibrators of identical sizes. Care must be taken to ensure that the non-foil side of the vibrator is smooth; this may require removing a layer of fiberglass. After this, we drill and tin tin holes with a diameter of 2.5 mm for the posts.

After making the vibrators, it is necessary to make a busbar (4) from brass or copper foil, with which we will later connect the “tails” of the vibrators.

All elements of the future antenna are ready, you can begin assembly. To do this, you need to find a spacer for the vibrator. Select its thickness so that the total thickness of the PCB and gasket gives a distance of 6 mm between the reflector and the vibrator foil.

To install vibrators, it is best to use smooth, thick copper wire with a diameter of about 2 mm. We cut it into small pieces and solder them in the “trough” holes. Then, placing a spacer next to the stand, we solder one edge of the vibrator, then the other in the same way, having previously moved the spacer. We bite off the excess parts of the racks. When installing, narrow vibrators are placed at the edges, wider ones in the center.

Antenna assembly

After installing the vibrators, we fix the connector on the “trough” and connect the “tails” of the vibrators using a busbar, carefully soldering them, then solder the central core of the connector to the busbar.

5. Installation

The easiest way to attach the antenna to a block is by drilling holes in the “trough” between the central vibrators and fastening it with screws or screws. If you plan to mount the antenna on a pipe, it is better to rivet an aluminum corner about 30 cm long to the antenna on the back side of the reflector, then attach the corner to the mast using clamps or ties.

Thanks to the forum participants for the information provided.

A few months ago, my work colleagues and I were faced with the task of connecting an access point from a remote house and a car at work with a mesh so that it would work well and packages would not be lost. Following the old saying “Screw copper!”, it was decided to connect with air. Why did we buy a fairly cheap WiFi card? But bad luck, the house is not right next to each other, although not a kilometer away, but still not nearby, but in direct visibility, about 150 meters. Of course there was a connection, but still the percentage was small. We went online to the website of a local store, looked at the prices for antennas... then a toad came :) With the words, “Well, screw it, I can do it myself,” I started a long, but entertaining and exciting job :)

I scoured the Internet for antenna diagrams, while learning and remembering the basics of physics, wavelength, polarization, etc. A pair of antennas were made from scrap materials, which turned out to be blanks. But as time passed, they ceased to satisfy us, so I will not delve into the manufacture of these antennas.

It was decided to do something like an adult and make a wave channel, or rather two at once, so that it would blow from both sides.
We found a diagram, thought about the material, and didn’t find anything better than using polymer pipes :) Here is a short photo report with comments.

1) A diagram of a 16-element wave channel was found.

2) I bought a pipe, cut it

3) I cut the elements. It was important to do it exactly with the circuit, because we would not have measured the wavelength on our own.
I brought a bar from home, cut the elements, then stubbornly ground off the extra millimeters and tenths of them

4) Measured and made holes in the tubes

Then, painstakingly and not without effort, I inserted each element into the holes, aligned
Next, I bought a 50 Ohm coaxial cable and connectors (the most expensive of the entire craft). Then everything was crimped and the antenna was ready :)

(after the photo was taken, the cable was shortened by half to avoid losses)

By the way, yes! Two wave channels were made in one working day, and it was Radio Day!
z.y. The percentages have doubled, we don’t lose packets, we have a stable connection...
before the antenna was ready the speed was 24 Mbit, after 48 Mbit

UPD: wave channel diagram with dimensions

UPD2:
materials that were involved:

Polypropylene pipe
- copper wire
- 50 Ohm coaxial cable
- SMA connectors