I Found the Secret to WiFi Antennas!

Added: 2026-05-25

[00:00:07]We all love a good WiFi connection meaning  a bad one is something everyone hates.

[00:00:13]And when that happens, there is usually  not much you can do about it when it comes to your router because it is packed  with highly engineered electronics.

[00:00:23]But one thing you sometimes can change is  the antenna; and trust me, there are tons of different antennas out there—different  shapes, different sizes—all claiming to improve your wireless connection. And I am curious myself, not only about how these antennas actually  work, but also which one performs the best and how easy it is to make my own. Because let’s face it: I tried diving into WiFi antenna design before in previous  videos, and so far I failed terribly.

[00:00:55]So let's not waste anymore  time and let's get started!

[00:01:07]This video is sponsored by Mouser  Electronics, who not only provided all the antennas and testing devices seen in  this video, but they are also giving out a free guide to antennas in the real world.  So click the link below to check that out and while you are already at the Mouser  website, feel free to browse through their huge electronics component selection to  find the components for your next project.

[00:01:34]Now to get started, I unpacked all the different  antennas I got for this video and once I was done with that I started taking them apart one by one  in order to find out what they are hiding inside.

[00:01:47]And all I could find were basically  different shaped conductors, sometimes in a helical shape, sometimes  straight, sometimes with a metal tube attached; the designs were truly interesting to discover. But they all have one thing in common; their job of converting the high frequency  alternating signal from our radio source, which can be your router or microcontroller  into a propagating electromagnetic wave.

[00:02:14]This wave then travels through  space and ultimately reaches a receiver antenna where the reverse then  happens and thus we can send over data.

[00:02:24]Sounds pretty straightforward; but  then why do all these antennas look different, if they all do the same thing?? Well, it has to do with resonance, because our electromagnetic wave is oscillating at a  certain frequency, with WiFi it is around 2.4GHz.

[00:02:41]But to better explain resonance,  let me use these tuning forks here.

[00:02:46]If I strike this one,then we can hear a tone  which according to the fork should be 440Hz.

[00:02:54]To prove that, let me quickly attach  a piezoelectric disc to the fork which can pick up mechanical vibrations and  let's hook that up to the oscilloscope.

[00:03:05]After striking the fork again, we can really see  a wave with a frequency of around 440Hz, nice.

[00:03:14]Now if I attach this piezo disc to other  forks and strike the 440Hz one next to them, then they all seem to care very little and  vibrate in pretty much no way whatsoever.

[00:03:27]The reason is that they all come  with different resonance frequencies.

[00:03:31]But if use a fork with the exact same frequency,  then it magically vibrates as well and this is the kind of resonance behavior we want  from out antenna pair as well so that we can transmit and receive data. But unlike a tuning fork which is a purely mechanical resonator, an  antenna is an electrical resonator.

[00:03:53]So the first important property to get an  antenna into resonance is its conductor length.

[00:03:59]You see for our 2.4GHz WiFi signal,  its wavelength is about 12.5cm.

[00:04:07]Simplified speaking, this wave travels in  our antenna conductor and the perfect size to reach a resonance point is at exactly  half the wavelength so around 6.25cm.

[00:04:20]Here is a animation from Wikipedia that shows this  phenomenon pretty well and truth be told we could spend hours here talking about antenna theory. So let's not do that and instead let's do an experiment with the, I would say  classical looking antennas I got here.

[00:04:38]Now I want to find out which one can  establish the best WiFi connection and for that we can make our life easy and grab  ourselves two ESP32 microcontroller boards.

[00:04:50]These come with WiFi and a uFL connector,  meaning I can hook up an SMA adapter and thus connect all my antennas easily. So what I did was using a bit of code to turn the first ESP32 into an Access Point  Transmitter and the second one into an receiver that connects to the access point and measures  the RSSI aka Received Signal Strength Indicator.

[00:05:18]This value looks something like this and  the bigger this value gets the better the connection and thus the better the antenna. But before getting to that I firstly wanted to find out how to best position the antennas  to one another and it was honestly no surprise to find out that when positioning both antennas  vertical to one another, we get the best results.

[00:05:42]The reason for that is their radiation pattern  which for such simple straight antennas is kind of like a donut shape with little radiation  on top and bottom and most to their sides.

[00:05:55]But anyway, with these basics out of the way I  chose a fixed spot for my access point antenna and used a vice and clamp for my receiver antenna. I did that so that I could switch between all the antennas on the receiver side while keeping the  same position and distance to the access point.

[00:06:15]And after measuring the RSSI for all my antennas,  the results were pretty clear but I wanted to be 100% sure and thus repeated this exact same  test with the access point in another room.

[00:06:29]Here are the final results and I think it  should be pretty easy to spot that there is a clear gap here that basically  divides my antennas into 2 groups.

[00:06:40]So let's firstly have a look at the better  performing group whose conductor length is around half the wavelength of our WiFi  signal like I mentioned it before.

[00:06:50]These types of antennas are called dipole antenna. And then we of course got the other antenna group whose conductor length is a lot shorter. These are called monopole antennas and their conductor length is only a quarter of our  wavelength so 3.125cm and in order to reach a resonance point, they simply use the attached  ground plane as the missing conductor length.

[00:07:16]So my monopole antennas were using the ESP32  Shielding and my metal vice here as part of the antenna which is pretty wild and only  this way they achieved such good results.

[00:07:29]And did you notice that my biggest antenna is  also a monopole and did not perform better than my dipoles meaning no; bigger is not always better. But anyway, with this experiment out of the way and new knowledge in my head; I wanted  to do a DIY attempt and it seems like a monopole was the easiest to do. So I simply removed the insulation from a solid core wire, cut it to around  3.2cm and soldered it to an SMA connector.

[00:08:02]And I actually included this DIY antenna in my  experiment from before and believe it or not, but it performed pretty much  as good as the other monopoles.

[00:08:13]But as you can see when removing it from the  metal vice aka scaling down its ground plane, then its performance does really  go down meaning a good ground plane is always important for such monopoles. And that brings us to the last plot twist in this video because while my DIY antenna  was cut nicely to the resonance length, the other commercial antennas are not really close,  but they also work fine, so what is going on?

[00:08:43]You see even it is just a piece of  wire, it always comes with some tiny inductance and capacitance which do matter  though at a high frequency like 2.4GHz.

[00:08:55]At resonance frequency, these have to chancel  each other out, so that no power gets wasted through them and that is the point you add  things like a helical structure or a metal tube to fine tune these values. So while length is definitely an important guide line, you also have to keep the  inductance and capacitance in mind and to make things even more complicated, RF systems  are usually tuned to a 50ohm impedance.

[00:09:24]That means your antenna also needs to match  this 50ohm, otherwise power gets reflected and thus your antenna is not performing great. But here is where we can use a helper tool, a so called VNA aka Vector Network Analyzer. After calibrating it and hooking up a commercial dipole antenna we can see that it performs  pretty great at 2.4GHz with close to 50ohm.

[00:09:53]However if, I hook up my DIY monopole then  we can see that it performs pretty terrible and only by attaching a ground plane,  we can somehow reach some ok values.

[00:10:06]And this is only the tip of the iceberg because  we have not yet covered things like return losses, gain of antennas, efficiency of antennas,  PCB antennas, Chip Antennas or the big directional Yagi antennas that can alter their  radiation pattern by using parasitic parts.

[00:10:25]Yeah, antennas are kind of like an art  form and I am really starting to like them, so be prepared for follow  up video about this topic.

[00:10:35]But for now we can say that if you want an easy  and reliable WiFi antenna, then do yourself a favor and get yourself a dipole one. With that being said I hope you enjoyed this video and learned something new. If so don't forget to like, share, subscribe and hit the notification bell. Stay creative and I will see you next time.