How to make an effective long-range Wi-Fi antenna with your own hands? Let's see in our calculator what the range of Wi-Fi depends on. We can see that most of the parameters are determined by the properties of our equipment, which we cannot change. But the greater the gain of the antenna, which we can make ourselves, the greater the distance range. Which antenna has the highest gain and what other criteria should you use to choose an antenna design? More details under the cut…
Most simple popular homemade Wi-Fi antennas, such as Cantenna or BiQuad, are limited to a gain of about 10 dBi. To increase gain, solutions are often proposed that have proven themselves at lower frequencies, such as VHF. One such antenna is Yagi-Uda. However, this antenna requires careful tuning by using the vector analyzer and has a complex matching unit at the feedpoint. This antenna may not work properly on the Wi-Fi range, even if you do everything exactly according to the drawings. Let's call this property the “repeatability” of the antenna. In other words, the lower the probability of a negative result when making a DIY antenna, the higher the repeatability. This is an important criterion for selecting the design of a homemade microwave antenna. Cantenna or BiQuad have good repeatability. Yagi has low repeatability. So, we need a high gain Wi-Fi antenna with high repeatability.
One of the best microwave designs that has good repeatability is the patch antenna. In order to increase the gain, we can use patch antenna array. Typically, such an array is called a “panel antenna” and is manufactured using PCB technology. However, the manufacture of microwave antennas using PCB technology requires a substrate with low losses and a normalized dielectric constant. PCB available to radio amateurs have a wide spread of dielectric constant values and high losses, so microwave antennas made of such material have very low repeatability and poor quality. A good solution would be to use an “air” substrate.
Here we offer such an antenna. It is an array of six patches. Let's call this antenna “Patch array 2×3”:
Antenna gain is about 17.5 dBi, SWR within the operating band does not exceed 1.25, suppression of the rear hemisphere of radiation is at least 35 dB. Input impedance 50 Ohm.
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| Impedance | VSWR | Gain | Radiation pattern |
Structurally, the antenna consists of a 230x360x20 mm box, closed on top with a radio-transparent plastic cover. To attach the front plastic cover, the side of the box can be additionally bent on the sides; for this, it is necessary to add a margin for bends to 20 mm of its height. Inside the box there are six round patches with a diameter of 65 mm. The spacing of patches vertically is 116 mm, horizontally – 90 mm, height above the reflector bottom is 7 mm. The middle array row locates exactly in the center of the reflector. The patches and the box are made of galvanized steel 0.3-0.8 mm thick. You can also use any suitable material. The patches are attached to the reflector with M3 bolts through plastic bushings or tubes 7 mm high and about a centimeter in diameter.
The patches are connected to each other by pieces of copper wire with a cross-section of 4 mm2 from the electrical cable. Soldering on top of patches. The lower wire bridge should have a straightened length of exactly 121 mm, excluding solder overlaps. It needs to be smoothly bent along guides with a diameter of 10 mm. The distance between the centers of these guides is about 78 mm. A strip 11.8 mm wide is cut out of brass or the same galvanized material and bent perpendicularly after 66 mm. The strip must be placed at a height of exactly 4.0 mm above the reflector. The bend is soldered to the bridge, the excess is cut off. The second end of the strip is soldered to the SMA or N-connector. The strip is a matching impedance transformer.
This antenna is not completely free from imperfections. For example, it has a fairly high level of side lobes. However, at high gain it has a large reserve of bandwidth. Therefore, the repeatability of “Patch array 2×3” is quite high, and this antenna can be safely recommended for DIY-ers who do not have a microwave impedance meter at hand.
Related links:
- Patch 2x3 @ 2440 MHz, 50Ω, 17+ dBi (+v2 75Ω) - author's description of the Patch array 2x3 design from yurik82, including a version with 75 Ohms input impedance;
Are there any losses if the box is larger in any(or all) of this dimensions?
The M3 bolts are metal, so the discs and reflector are electrically connected. You should bear in mind that a DC short is not a short at high frequencies.
We are dealing with galvanized steel, not just steel. In this case, you suggest replacing zinc with copper. Then the gain increasing will be about 0.04 dB. This is a very small value. More details here:
3g-aerial.biz/en/choice-of-material-for-the-antenna
(i) For connecting the patches, you specify 4mm² copper wire. Unfortunately, I couldn’t find this size—neither in my garage nor at the local hardware store. The closest options available to me are 3mm² or 5mm². Which of these would be more suitable? Or would using either be a problem for the design?
(ii) You use metal bolts for the patch disks. I saw that someone has already asked about this, but I’d like to follow up: Would it improve the antenna’s performance if I replaced the metal bolts with nylon bolts or screws?
(iii) Could the design be adapted for MIMO usage? I was considering a square array with 3x3–1 (i.e.,
Many thanks in advance for your help!
I answer your questions:
1) Both wire diameters are suitable. However, changing the wire diameter will affect the VSWR value. How far? Additional calculations are required to answer this question.
2) This will not improve the antenna performance.
3) This is a completely different design that requires separate development and optimization. With this design, it is possible to use two separate antennas.
I'm new to this and trying to build this antenna for the first time. I have a couple of probably silly questions about the screws.
I saw the talk about using metal or nylon screws. So, my questions are:
1. If I *do* isolate the patches from the reflector (like, use plastic screws and washers), will it make the antenna's performance **worse**?
2. I actually read the opposite on another forum about a different antenna. They said that you **should NOT isolate** them at all! They claimed that if you *do* use insulation, you could actually **fry your Wi-Fi adapter**. Is that true? I'm confused now.
Thanks for helping a newbie out
For these reasons, using metal bolts is preferable, as is the case in this design. Any design change, including replacing metal bolts with plastic ones, may also degrade the antenna's performance and requires recalculation.
No. It's not suitable as a parabolic antenna feed. The problem is that the higher the antenna's gain, the narrower its main lobe. In this case, if the feed has high gain, it will only illuminate part of the dish, and the overall efficiency and total gain of the “dish & feed” system will drop significantly.
3g-aerial.biz/en/universal-3g-4g-wi-fi-mimo-feed-for-satellite-dish-wbme