Homey Community Forum

Homey antenna mod

Yep, i did.

Another question!
Can’t find the answer though I searched, what length should I order of this pigtail cables?

On post 32 above you find a link with the pigtail cables I used.
Spare to search, mine was 4” (10cm).
It depends where you want to mount the antennas, top half of the dome, 4” or shorter. Bottom half, 4” but not shorter.

Thank you!

My next question is.
Are these pigtail cables that come with antenna so much worse than these “better” ones you refer to?

In my case one antenna came as a kit, for the other I had to buy it separately.
The pig tail is not usually the problem, they are all more or less the same.
In my case the one that came with the antenna was very thin, it looked like the screen was almost non existent yet, it has the same performance as the separate one I got which was quite thick.
The antenna matters the most as well as the workmanship you do especially on the z-wave mid as soldering is necessary.

what’s the best antenna/pigtail for a zigbee mod?

Trouble with zigbee??? Read this pdf i have found on the internet. Very…VERY usefull for zigbee setup

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.control4.com/docs/product/zigbee/best-practices/english/latest/&ved=2ahUKEwiWovTKvprmAhWP-aQKHa1-ATYQFjAYegQIAxAB&usg=AOvVaw07ifkp5PJhEBwyhmoXS-iu

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Indeed a very interesting PDF. Unfortunately we cannot do everything which is suggested, but it gives a lot of clearity.

I cannot silence myself anymore.

The antennas built in Homey are tuned to its working environment, This is done since the Home have to follow regulations like En 300 086, EN 300 720 etc. depending on the purpose of the transmission.
We don’t want the radio equipment to harm people or interfere with other electrical/electronic equipment radio based or not (according to the EMC directive all electrical equipment should be tested, you don’t want a life support critical equipment to fail just because someone answers a cell phone nearby)
Just how big is the difference between a WiFi AC access point and a microwave oven?

To turn up the transmit power are often suggested as a solution to too short range communication, but we also have a receiver, mostly coupled to the same antenna for obvious reasons.
The simplest way to add more power is to add a small line amplifier, these small units will probably only work one way but they often have a broad frequency spectrum, they are made to compensate lile loss in very (very) long antenna cables.
Line amplifiers only work one way hence blocking the receive signal and your receiver will be deaf.
The smartest move might seem to get a more sophisticated amplifier that have a receiver signal pass thru functionality,
this will only work on duplex channels/frequencies where your transmitter send and receive on two different channels/frequencies i.e. cell phones (GSM) and other point to point network.
Amplifiers will not work good in a mesh environment. In a mesh environment we use digipeaters that relay a message.
A digipeater receives and retransmits digital signals on the same radio frequency. Compared to a “parrot” that will receive and retransmitting analogue voice messages. It takes some time to relay the message but overall it should work really good.
A repeater receives and re transmits simultaneously and can do this for both analogue signals with no apparent delay, and digital signals that will have a very small delay added due to error correction.
A repeater solution is not as cost effective as a digipeater solution since the radio must consist of analog filters separating the receiver and transmitter frequencies and this is costly in money, in sensitivity for the receiver and in transmit power for the transmitter.
Back to the transmit power dilemma again;
If you make the transmitter 10 times stronger you also have to make the receiver 10 times more sensitive, but you can´t, not without adding noise.
Think for a moment that you are listening to a poor radio broadcast from far away, you will have difficult to hear due to undesirable noise,
if you turn up the volume, will the noise disappear? No, it will just make your ears bleed…
So, to gain distance you will have to make ALL transmitters the same, compared in transmit power.

That being said, what can we do?
We can plausibly make the antennas work better i Homey, but to do that we need to have some basic understanding on how the antenna actually work and how to connect it i a good manner.
We have the obvious to choose from;
coaxial connectors, coaxial cables, dipole antennas, helical antennas, 1/4 or 5/8 or 1/2 lamda wave antenna, we have antenna arrays, stacked antennas, yagi antennas, parabolic antennas etc.
Some are talking about antenna impedance, power, gain etc.
Since an antenna is passive(!) it can not generate any power or add gain in any way, sorry but it’s the truth.
WE can however construct the antenna to have specific advantages, for satellite communication we use parabolic dish antennas, we are doing that because the parabolic shaped dish act the same as the reflector in a flashlight,
sending the signal in one specific direction. The “gain” in this situation is that we only send/receive in a small “window” and are less likely to be disturbed by another radio signal from our surroundings.
The best omnidirectional antenna is the dipole antenna it is the closest thing we have compared to the mathematical isotropic antenna that many compares their antennas with.
The antennas that are used in Homy are helical antennas, I have not measured the physical legts of the wire that makes up the helical antennas (in air, twisted conductors that make up the antennas)
Usually you curl the antenna wire to save space, in this case they probably wanted to fit the antennas inside the Homey case.

This is beginning to get advanced so I will try to keep it short.
Antennas are actually just passive resonators and they have working range (often called bandwidth) that differs from antenna concept to antenna concept.
This works a little like the string on a stringed instrument, If you don’t tune it correctly it won’t perform as you would like it to do.

Regardless of the system impedance (usually 50 or 75 or 90 or 300 ohms etc.) you must aim to have the same impedance all the way from the transmitter amplifier to the top of the antenna.
A thin antenna wire will only have the correct impedance on a really small frequency span, if you change frequency you will get another impedance and the antenna impedance should be re tuned.
This is virtually impossible since just a small conductive object close to the top of the antenna will influence the electrical length hence the impedance…
Luckily the antenna is much less sensitive at the base of the radiator (often mistakenly called the antenna, but this is only about half of the actual antenna solution)
Most antennas on the market wot RP SMA connectors need a ground plane to work properly, not many have a proper ground plane, but some antennas actually facilitate a built in one…
I think that this might be one thing that could have been made better in the Homey, they could have made the bottom part as a ground plane and probably enhance the antenna functionality with 50-100% for 434 and 868MHz
434 x 2 = 868Mhz and that also means that a 1/4 wave antenna for 434 MHz really is a working 1/2 wave antenna for 868 MHz.
A antenna wants to live free from anything than air especially conductive materials, that being said, it is not by chance all antenna towers are towers.
Radio waves are electromagnetic radiation, exactly like light, the only difference is wavelength. Radio waves are often measured in centimeters or meters but light is measured in nanometers.
Is anyone still reading?

I am however glad that most of you who modded your homey, made it work better.
The antennas you are using are should have huge impedance problems, but since most of you invented a new type of antenna by NOT connecting the coaxial cables screen to radio signal ground.
Adding short, but high loss, cables (the diameter is too thin to be low loss cables) My educated and sincere guess is that you actually made the transmitter much worse,
but you have moved the sensitive antenna tip away from the circuit board and also elevated it, giving the receiver in Homey better workspace.

If anyone reads this to the end, it would be very interesting to replace the curled antennas for 434 and 868 MHz with two antennas angled 90 degrees in between since I suspect that they interfere a little with each other. If anyone decides to try it would be really interesting to take part of the results.
For all of you who have a long cable to the antennae, try to shorten it, but if you didn’t bother to solder the screen of the coaxial cable it will probably not matter.
If you are sing a magnetic antenna foot, it must be attached to something large and metallic (=refrigerator door) or you will not have a working ground plane. If the antenna has no coil the direction shouldn’t matter, if it has a district horizontally pattern when it stands up.

The following link might fill in some blanks:

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Thanks for the elaboration!

But this

must by far be the understatement of the year 2019 :stuck_out_tongue:

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:wink: Luckily there is not much left of the year 2019

Thats why we use @ work in 99% of the time dipole antennas for use in the tetra network :+1:

Very nice info to read.

Do you have any picture, sketch, drawing - whatever… - that explains what is what inside the Homey globe? Right now it’s more or less guesswork.
Some electronic devices have a service manual, but that will probably only be wishful thinking for the foreseeable future.

https://homey.app/en-us/blog/a-technical-introduction-homey/

Dipoles are easy to build, commercial dipoles are also quite forgiving to use, and overall dipoles are relatively easy to calculate. The basic T-shaped dipole might not be the most beautiful antenna to look at, but then not many antennas are.

That being said, mostly because I do understand antennas but less that digital, self organizing nodes that tend to work as efficient and reliable as the English parliament, well I’m Swedish so what do I know :wink:

But I wonder why so many seems to have wave propagation problems with ZigBee, my problem seems to lay solonly in routing. Everything seems to go slow, same bulbs repeatedly fail to communicate but then decides to work the fifth time you try even if all other bulbs around works the first time and they all have direct connection to the Homey. Trying to use Google home to control everything makes everything even more complicated since Google tends to randomly skip bulbs that are easy to maneuver in both the Homey app and the Google Home app. and Google is the master of masters in complaining verbally, sometimes google home reports failure before even trying…

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