31.12.2019
Posted by admin
In this section, we’re going to discuss how to increase WiFi range using the right antenna for the job. We’ll discuss various antenna types, how they work, cable lengths, and coupling requirements. Most of you will be using the default antennas that come with your router. But for those of you planning to boost your range, using the right WiFi antenna can save you a lot of time and frustration. And with some basic knowledge about antennas, you will be better prepared to troubleshoot problems and plan your deployment. How do WiFi antennas work?First and foremost, frequency wavelength plays a key role in the construction of the antenna. But other factors such as are equally important.A 2.4GHz antenna will not work with a 5GHz signal and vise versa.
If it does work, it will not work properly and the range will be terrible. So, whether you are buying an antenna or building your own, make sure it’s designed for the correct frequency band. An antenna provides three things to a radio transmitter:.
Direction. Polarity. GainDirection refers to the shape or angle of the transmission, which ultimately describes the coverage area. Polarity is the orientation of the electric field (the transmission itself) from the antenna. Gain is the amount of energy increased by the RF signal. What is an omnidirectional antenna?For starters, Wi-Fi antenna’s are either omnidirectional or directional. Omnidirectional antennas are designed for 360 degree operation whereby a vertical dipole radiates and receives equally well on the azimuth plane (in all horizontal directions).
Rubber Ducky AntennaThere may be times when your rubber ducky just doesn’t cut it. When you need more range, a directional antenna might be your best option.
What is a directional antenna?Think of directional antenna’s like a water hose with a garden sprayer. When you squeeze the handle, the water is sprayed in a straight line.
When something gets in the way, the pressure will either blast through it or bounce off if it, depending on the density of the object.Since directional antenna’s focus their energy in one direction, they are excellent for controlling the direction of the broadcast, or receiving a distant broadcast. Parabolic AntennaParabolic antenna’s work by reflecting the signal off of the rear reflector and concentrating that signal into one central point. If you want to test the parabolic theory, hold a large bowl in front of your face and speak into it. The audio from your voice travels to all corners of the bowl, but when it’s returned to your ears, the sound is magnified.Like the Yagi antenna, parabolic antenna’s are a common choice for point-to-point environments.
The coverage width and elevation is comparable to that of a Yagi antenna. The “dish” is more prone to wind, snow, and ice.
Consider using a “grid” antenna for areas with high-wind and freezing weather.Here are some reputable places to buy antenna’s:.Cantenna WiFi Antenna. CantennaCantenna’s are mostly used as a receiving antenna for client computers. Most people use them to replace the rubber ducky antenna’s on their wireless USB adapters connected to a laptop. Cantenna’s are a great addition to your travel case. They can help you reach Wi-Fi hotspots that might otherwise be out of reach.There are a lot of DIY enthusiasts these days. Many of them post images and plans of their homemade antenna’s. Some are downright ugly.
Others are quite impressive. They’re made from everything you can imagine: coffee cans, Pringles cans, trash can lids, etc.Here are some DIY examples:What is antenna polarity?Regardless of the type of antenna that you use, there is one thing that absolutely must be correct and that is the polarity.
The broadcasting and receiving antenna must use the same polarity. Good performance is all about a strong signal. Radio wave “polarization” plays a huge part in signal quality.
Polarization is determined by the physical position of the antenna. Antenna PolarityPolarization is extremely important. In fact, if you had two antenna’s pointing directly at each other, one with perfect vertical polarization, and the other with perfect horizontal polarization, the antenna’s would not hear each other at all.Omni-directional antenna’s are vertical polarized.
A Yagi antenna with vertical elements is also vertical polarized. But if you turn the antenna so that the elements are sideways, the antenna is then polarized horizontally. What is Antenna Gain?The range and strength at which an antenna can connect depends on the antenna’s gain.
Some people say “power” but what they really mean is “gain”. Unlike the actual radio transmitter itself, antenna power is not measured in output power. It’s called “gain” and it’s measured in a relative unit known as “dBi”.For the transmitting antenna, gain is the measurement of how well the antenna converts the transmit power into a radio wave that can be sent. On the receiving end, it’s a measurement of how well the antenna receives the radio wave and then converts that to electrical power.
What is dBi and dBm?This can make your head spin when shopping for antenna’s. Just remember, the general idea is to reduce the amount of loss and retain as much gain as possible.Antenna Gain and Cable Loss are values that are constant no matter what power level you are referring to. Antenna gain is affected by “cable loss”. Cable loss is associated with anything that decreases the antenna’s gain, such as the length and/or diameter of the antenna cable.dBi is an “isotropic measurement”. That’s just a fancy way of saying that dBi is a relative measurement.
So, it doesn’t really matter what level of power is in question, the dBi remains the same.dBm refers to the ratio of decibels (dB) to milliwatts. The referenced unit is exactly one milliwatt. Since it uses a reference point of exactly one milliwatt, it is an absolute unit of measure. The conversion of watts to dBm uses a complex formula that goes beyond the scope of this section. In short, 1 watt (or 1000mW) is equal to 30dBm.If you have cable loss of 2 dBi (based on your cable length and diameter), but a gain of 7.5 dBi from your antenna, the net effect is +5 dBi regardless of the power level.
What cables should I use for my WiFi antenna?With outdoor applications and runs over 4 feet long, use low-loss cable such as: LMR-400. If you have a 20 foot run, use 19 feet of LMR-400 for the main line and the smaller LMR-100 cable for a 1 foot pigtail equipped with the connectors you need. Your pigtail may have an N Female on one end, and an RP-SMA Male on the other.
What are the most common antenna connectors? Outdoor WiFi AntennaDrive a solid copper rod (4 feet or longer) into the ground. Run a solid copper wire (8 AWG or larger) from the lightning arrestor to the grounding rod. Secure the ground wire to the copper rod with a with a grounding strap. Make sure it’s tight.
If it’s not grounded properly, the lightning arrestor will be have nowhere to dump the excessive voltage.Let’s recap:WiFi antenna’s are designed for specific frequencies (2.4GHz, 5GHz, etc). The direction of the antenna, the polarity of the signal, and the gain of the antenna are all for the intention of getting radio waves to and from the transmitter. Maximize signal quality by matching polarity.
In order to get as much signal to and from the radio, the idea is to minimize loss and retain as much “gain” as possible. In order to achieve maximum gain, use low-loss cable. And last but not least, protect your indoor equipment from lightning. Use gas-charged lightning arrestors and secure them firmly to a copper grounding rod.
The building steps are simple:1. Print out the scaled Yagi antenna template. (download from next step).2.
Trim paper clips to size and glue them to the template.3. Use Popsicle sticks to build the antenna's backbone and hold it together.4. Connect the USB device to the antenna.I used a Yagi modeler java applet to generate the diagram. This modeler applet is found on many websites (google 'yagi modeler') and its owner is.The modeler gives a diagram and the elements' lengths and position.
I carefully scaled the diagram and turned it into a template in order to make the building process easy.You can visit awesome website to get more details on using the modeler for this 15 element Yagi and other fine antenna projects, such as a 20 element WIFI Yagi. The most essential point in printing the template is getting the correct scale. In the attached zip file below, are three png picture files.The antenna is longer than an Letter sized or A4 sized paper. So you have to print the template in two parts (labeled part1 and part2 in the zip file).
I have also included the full sized unsplit template if your printer can handle large enough paper.PRINTING:Make sure to set your printer's properties to ORIGINAL SIZE (not 'best fit to page' ect.).Set the print orientation to LANDSCAPE.VERIFYING SCALE:Use a ruler or caliper to measure if the print is of correct scale. You will notice vertical bars crossing the horizontal line.
The vertical bars represent the Yagi 'elements' which will be made from paperclips. The horizontal line is the backbone of the antenna which will be build out of popsicle sticks.You will also notice numbers next to the elements.
These numbers are in pairs. The first number is the length of the element in millimeters. The second number, is the distance from the start of the diagram to the element, in millimeters.Measure the size and position of a couple of elements on each prints. If your measurements match the numbers on the diagrams, then your print is to scale and you may proceed. Accuracy need not to be tight for the antenna to perform well.Now superimpose both prints, until they match at around element 10 or 11, and tack them together with scotch tape or white glue.
You have to trim the paper clips with a nibbler or plier to fit the vertical bars ('elements'). This is fairly straight forward. Lay the paper clip on the template's element and mark the ends with a marker. Snip at the marking.Make sure that each element fits correctly the length of the bar on the diagram.Fix the elements in place with crazy glue.Leave element #2 for later.
This is the element that connects to the electronics and is called 'the driven element' (as in being driven by electronics). The 'driven element' in a Yagi antenna, is usually the second one from the start. It is the element that connects to the USB WIFI or 2.4 GHZ electronics.It is a broken loop and not a straight wire.
A loop of wire resonates at a specific radio frequency depending on its dimensions. The dimensions of the driven element in this antenna is set at 2.4GHz, of course.It just happens that its about the size of a common big paper clip.
You need to clip the paperclip so that it loops around and meet in the center but the end not touching, leaving a gap (see photo).Fix it in place with crazy glue and build the back bone around it.When all the elements and sticks are in place, reinforce the antenna with another layer of popsicle sticks. Glue full lengthed popsicle sticks on top of the antenna.
The antenna should become mechanically stiff. Then rip the paper template of the antenna. This is the most difficult part and depends on the electronic hardware you have. Please read this step carefully.The basic idea is that you need to solder a wire between the WiFi board's RF output and the driven element of the yagi antenna.But USB WiFi modems come either with an internal antenna or with an external antenna.
Those with external antennae, like mine, are easier to connect because you are just replacing the external whip antenna with the Yagi. Those with internal antenna may need to have their on-board strip antenna modified as illustrated in the pictures here. You need to slightly experiment in this case.I have tried soldering a coax to my board's antenna connectors and the two ends of the yagi's active element loop but it did not work in my case.
I have no explanations why that did not work, but other DIYers that have built Yagi antennae connected their antenna in this manner.In my case, I just connected a single thin strand of copper wire between the active element of the strip antenna and one end of the loop of the driven element.Please read the annotations of the pictures for more details. Okay well I read through the entire post and I saw many things that made a lot of sense, also saw a lot of unnecessary flaming, but I do have a few comments to make. Right off the bat the one individual that asked about having his modem in the basement with a rotating antenna on the roof needs a reality check. Overlooked in the connecting the USB dongle to the antenna was the transmission line length, for these frequencies it should be as short as possible and a multiple of 1/2 wavelength I'd suggest as close to 2.41 inches as one could manage (use a small diameter 50 ohm coax). Take the dongle apart and connect a USB extension cable to it and mount it directly on the antenna assembly.
Paper clips vs copper, at this frequency it's not going to make much difference, however the specific model was generated using 14awg copper. Someone said glue it all to cardboard then cover it with more cardboard actually a strong and stable design, original author said build around popsicle sticks(wooden), both are subject to absorbing moisture from the air and either can have a poor dielectric constant, I would suggest some kind of plastic (they make popsicles with plastic sticks). The lengths of the elements, the spacing between them, and keeping them all in the same plane and parallel to each other is the most important consideration.
The driven element, #2 in this design: that one I would make from 14awg copper, I'd make a simple dipole rather than a folded dipole, I would take two pieces of wire make 90 degree bends in them cut the bent part to about 1/8 inch and attach my transmission line. Take a piece of heat shrink cut two notches in it about 1/4 inch apart and insert the wires into it and shrink it, maybe reinforce the space in the center (break a tooth from my comb and stick it in the middle before heating the shrink?) cut it down to the correct overall length and insert it last.
If you use the folded dipole make sure the folded part is perpendicular to the plane of the rest of the antenna and use 300 ohm twin lead to connect to the dongle, but your SWR will probably be much higher, reducing your effective gain and possibly resulting in early failure of the dongle. Horizontal vs vertical, after you have your antenna connected and have connected to some network you can try rotating it about its horizontal axis to see if you can get a better aspect on the other antenna (more bars). All in all though good job to Biotele, it's cheap, it's easy, and if done right will provide excellent results. I did not build this antenna, but I built 2 antennae very similar before reading this post, My son and I live almost 2 miles apart and either of us can stream 1080p movies from the other's house during a thunderstorm. As others have pointed out, the impedance matching is done poorly and not even explained properly. I have added a picture of a matched element that also acts as an impedance transformer.
The 2.4G wavelength is roughly 5in and the total wire length used in the design should be half of that, but also multiplied by the slowdown factor which is roughly 0.7. That means you use a 2in wire, solder the center of the coax to its center, then fold one leg in half and solder it to the shielding.
This is why those internal laptop antennas out of stamped metal have that shape. It's the quarter-wave hoof. I understand that skin effect is paramount to impedences and that if you increase the diameter of the driven element you can also increase the bandwidth and decrease the impedance to like 50 ohms and that a good measuring stick is your best friend in building these things as long as the math formula is good. But to keep resonant a yagi-uda myst always be tuned for each frequency wanted. A tube within a tube allows you to adjust such lengths. Skin effect means tubes are better than wires which are heavier.
BUT, where are the formulas for the driven lengths vs diameters and velocity factors of whatever cables? That is 6 MHz. Wifi he is describing is 2400 MHz. Take a look at a stepper ir. They tune thru that band and are around $6000. It is a huge antenna but very good. It is a loop like the formed paperclip.
In case you are confused, the term meters is the actual physical wavelength in meters of the transmitted signal. The lower the frequency the bigger the antenna has to be.
It is factored on 1c, which is the speed if light, 299792458 meters per second. Rounded to 300,000,000 you divide this by the frequency in cycles to get the full wave length. Shorten it by using 300 for length of light / speed and 6 for the MHz instead of cycles and you get 50 meters. A balanced antenna such as a dipole is a 1/2 wavelength, so divide that by 2 for the physical length of a 50 meter dipole, so 25 meter length is correct. For 50 meters you are talking about a huge antenna.
You can build an active antenna for just a receiver or use an LC network to tune a shorter wire but it will be compromised in ability. Hint: the antenna is a network, compromising of everything from the board connection point, all the way to the tip of the antenna. Using coax, you will also need a balun.
I'm an extra class ham radio operator and an electrical engineer. Look online for antenna calculators will be your best bet. Beverage antennas are great, especially for summer time noise from lightning static crashes but they are even bigger.
Sorry for the delay on the post but I just saw this. One more thing. If you are mounting this any distance from the wifi, db loss is extreme on higher frequencies like wifi 2400 MHz. Keep the coax short as possible and use cat5e to get to your laptop. LMR400 is a good all around coax but is is nearly 1/2' diameter. The higher the frequency the larger the center conductor has to be because of 'skin affect'.
You can use a short piece of smaller coax and then adapt it to a larger coax. LMR has superior shielding also. Every 3db loss is half of the signal strength. 6db is 75% loss. 9db is 87.5% loss. Every 3db cuts it in half each time in the math.
Antenna gain and loss are added to get the ERP.effective radiated power. 5db loss of coax with 8 db gain on the antenna will give you 3db gain so you can double you wifi output power to get the ERP. Just look into a Ubiquity wifi and their antennas. They are nearly 30dbm.1 watt with some very high gain antennas. That can get you 60 km distance if applied correctly.line of sight.
Build Yagi Wifi Antenna
The average person is not going to be able to make this because it leaves out the most important step; so I'll try to explain without going into the math: Matching the impudence of the feed line (the wire that connects to the folded over paper clip). RF signals at this high frequency is VERY sensitive to length. It is critcal to cut the lengths perfectly, also the lengths are for copper wire not steel. So the best material would be solid copper wire that you can buy at the hardware store.
Build Yagi Antenna Wifi Antenna System
I used 18ga and kept the lengths within a millimeter of the size.1. For the connecting wire you MUST use 50 Ohm coax cable.
It comes in 75 or 50 Ohms and its usually printed on the side. If you use a plain old wire this becomes part of the antenna and you lose the 'quarter wavelength' that tunes this antenna to 2.4Ghz. Bigger is NOT better with antennas. The best reception comes from keeping the antenna element EXACTLY at this length.
Skipping this will give you worse reception and there is no point in making at that point.2. Solder, dont tape the center conductor of the coax to the center paper clip at the very edge of one end.
Don't form a loop, keep the ends electrically separated and keep the paper clip at a 90' angle to the other paper clips, don't lay it flat, that messes up the length between the 1st and 3rd paper clip which are the most critical lengths.3. Keep the coax as short as possible.
Anything over 3' is going to turn the coax into part of the antenna and this can burn out the wifi transmitter. Download infinite flight simulator mod apk. When you solder it to the trace make sure you connect it the beginning point if the antenna if its a 'squiggle' shaped antenna on the circuit board.
If you solder to the end you have screwed up the length. You will also have to scrape away part of the trace that forms the rest of the antenna, this is permanent so it your not sure be cautious. If there is a connector it will be very tiny and the best way id to cut the cable coming out and connect that. The inside of the cable goes to the inside of your coax and the out must also connect.
How To Yagi Antenna Wifi
Some coax cables have aluminum and solder wont stick to it; while still useable it may not be the best choice if you are not experienced with building electronics.4. Better way to make the driven element: The outside conductor of the coax must be connected to the ground of the wifi device. This will be outer ring of the connector in your device, this will connect to the shield of your coax. Take the folded over paper clip like in the tutorial but instead of making a loop, make it the length in the print out as a straight piece. Cut the piece in half. This now becomes a dipole antenna, and will work better because it used the ground in your wifi device.
Solder the center conductor of the coax to one half and the shield to the other half and glue them onto the popsicle stick with a very small gap between like in my picture.5. Finding the ground: this is probably the hardest part. For this to work you need to hook the outside of the coax to the ground.
If there is a connector in your wifi device it the outside conductor of the connector. If you just have a squiggle you are going to have to find the ground plane on the circuit board. This is usually a very thick trace that 'floods' the circuit board where one side of most of the parts connects to. There is really no easy way to spot this without some knowledge of electronics. If you don't do this step it may still work but wont work well if it does defeating the purpose of this DIY.If you want to learn more look up wavelength and 1/4 wave length.
Its a complicated subject with lots of math. Unfortunately this project just wont work if you skip steps or mess anything up. Seems simple but really everything has to be done right for it to work. Hope this helps.