Extending Wi-Fi range - Page 1
Forum section: electronics / rf-microwave

author: Flo
author_rank: Newbie
timestamp: April 30, 2018, 08:56:23 am
content: Hi guys,Small introduction: I’ve build a (quite over the top) rc boat which I use during fishing to drop my lines in exactly the right spot.In order to find the best spot, a sonar is used to measure the depth. I've tried a few systems; a marine sonar combined with Arduino’s and rf modules, and a cheap fishing sonar system. But both systems didn’t function good enough.So a bought a better of the shelf system. It gives a very good picture of the bottom structure and even combines the depth with gps coordinates to make a depth plot of the lake. The interface is a phone or tablet and it uses a Wi-Fi connection.Because it’s a Wi-Fi connection the distance is limited to ±100m. I would like to extend the range to around 250m.After some research I’m thinking about removing the onboard antenna and soldering a coax cable directly to the pcb (shield to ground plane and centre wire to the spot of the original antenna). Add a (2w) signal booster from ebay and attach a standard WIFI antenna.Photos of the pcb:https://fccid.io/2AHKO-PRO/Internal-Photos/Internal-Photos-3001586.pdfWi-Fi module on the pcb:https://wireless.murata.com/eng/type-zx.htmlFirst question: do you think this is a good idea?There are some capacitors and resistors between the Wi-Fi module and the original antenna and from the signal trace to the ground plane. Should I remove these components and solder the coax cable directly to the signal trace?Do you perhaps have a better idea to enlarge the range?As a mechanical engineer with an interest in electronics, I’m quite a bit over my head with this. So I’m asking for your expert advice.Some photo's:

author: Jeroen3
author_rank: Super Contributor
timestamp: April 30, 2018, 09:04:22 am
content: You can get much better range with 2.4 GHz if you use the right antenna's. Search in the FPV (model airplane) market.

author: Lord of nothing
author_rank: Super Contributor
timestamp: April 30, 2018, 01:11:53 pm
content: How about 5Ghz WIFI who can use outdoor 1W legally.

author: ogden
author_rank: Super Contributor
timestamp: April 30, 2018, 03:50:06 pm
content: Quote from: Jeroen3 on April 30, 2018, 09:04:22 amRight. You shall be able to get decent range just by using proper antennas. As your boat is comparably big, you can put hi-gain omni antenna on it. Google for "2.4GHz High Gain Omni-Directional antenna". Be sure to get "branded" antenna, use high quality, low loss coax cable.Antenna like this one is goodbecause cable included, no loss in (SMA) connectors which you don't need.If antenna on the boat is not enough, then you can add (install on the ground) WiFi range extender (like D-Link N300) which most likely will have much better antenna(s) than that in your phone.Forget about amplifiers. Seriously. They are illegal in most parts of the world. What's worse - most of fleabay "WiFi amplifiers" are nonlinear garbage which will pollute out of band frequencies. Nice, well-built RC boat!

author: Flo
author_rank: Newbie
timestamp: April 30, 2018, 06:11:44 pm
content: Those are excellent tips, thank you!I'll give it a try with a good antenna and without the amplifier (probably with the extender as suggested).should I remove C20 and R100?the components look a lot bigger on the photo than IRLQuote from: ogden on April 30, 2018, 03:50:06 pmThanks!

author: CopperCone
author_rank: Super Contributor
timestamp: April 30, 2018, 06:45:36 pm
content: how does that work? You attach the line to a magnet or something on the bottom of the boat and it drops it like a bomb?How do you prevent it getting tangled in weeds if its towing a line?

author: Flo
author_rank: Newbie
timestamp: April 30, 2018, 07:08:07 pm
content: There's a servo operated hook release on the back:https://youtu.be/26mFp3RGLj0There's also the possibility to drop extra bait to attract the fish.As long as you sail in a strait line and keep the line somewhat tight, it doesn't get tangled up.The main reason for using such a boat is that max casting range is around 60 meter, and the hotspot is sometimes over 200 meter away. (and it's fun to build of course)

author: David Hess
author_rank: Super Contributor
timestamp: April 30, 2018, 08:00:13 pm
content: I would use a pair of Ubiquiti CPEs as an Ethernet bridge to connect the boat to the tablet. The one pointing at the boat can be elevated and use a directional antenna.

author: ogden
author_rank: Super Contributor
timestamp: April 30, 2018, 08:10:11 pm
content: Quote from: Flo on April 30, 2018, 06:11:44 pmC20 shall stay definitely. Good question about R100. It could do some antenna impedance matching or (most likely) work as "dumb" TX power attenuator. Could you measure DC resistance of it?I would:1) do max TX distance tests using existing antenna, to get base line2) do max TX distance tests with shorted R100 (just solder some wire strand over it)3) do max TX distance tests using 3rd party >=8dB4dB omni antenna connected in place of on-board antennaIn short: testing is best way you get what you want from RF

author: Flo
author_rank: Newbie
timestamp: April 30, 2018, 09:06:46 pm
content: I’m measuring a resistance of 0,2-0,4 ohm.

author: DaJMasta
author_rank: Super Contributor
timestamp: April 30, 2018, 09:12:12 pm
content: Quote from: Flo on April 30, 2018, 09:06:46 pmZeroing the probes first? Is there any marking on the resistor?It could potentially just be a 0 ohm jumper and you're measuring contact resistance.

author: ogden
author_rank: Super Contributor
timestamp: April 30, 2018, 09:17:09 pm
content: Quote from: Flo on April 30, 2018, 09:06:46 pmThen let it be. Seems like safety pillow component "we will put inductor there if we need to tune antenna impedance for TX frequency". Both C20 and R100 stays.

author: CopperCone
author_rank: Super Contributor
timestamp: April 30, 2018, 09:29:04 pm
content: why does it have a bottom opening door?

author: Flo
author_rank: Newbie
timestamp: April 30, 2018, 09:31:18 pm
content: Touching probes measures 0,2 ohm.It does look like there’s an extra connection between the trace and the ground plane on the other side of the pcb. I can’t take the pcb out at the moment to check. (It’s kinda stuck and i don’t want to break it...)Edit:Perhaps C29

author: Flo
author_rank: Newbie
timestamp: April 30, 2018, 09:34:34 pm
content: The bottom door is for depositing extra bait to attract the fish. The boat can carry up to a few kg of extra bait.

author: CopperCone
author_rank: Super Contributor
timestamp: April 30, 2018, 09:36:37 pm
content: oh I thought bait had to be on the fishing hook, I don't fish.

author: CopperCone
author_rank: Super Contributor
timestamp: April 30, 2018, 09:38:03 pm
content: CIA MKULTRA edition:

author: hagster
author_rank: Frequent Contributor
timestamp: April 30, 2018, 09:52:06 pm
content: While i agree that the antenna on that is probably fairly poor(probably between 0 and 2dBi), if you dont know what you are doing when connecting a new connector of coax, you could easily make it worse. Best case for a high gain omni is about 9 or 10dBi.You could perhaps more easily put a high gain directional panel or yagi antenna(with propper 50ohm rf connector) at the conrroller end and get the same range extension more easily. It should be easy to get something with 18 to 20dBi gain for this end.

author: Flo
author_rank: Newbie
timestamp: April 30, 2018, 10:01:55 pm
content: Quote from: CopperCone on April 30, 2018, 09:36:37 pmAh well, i spend more time behind my desk working on this than on the waterside

author: helius
author_rank: Super Contributor
timestamp: April 30, 2018, 10:06:15 pm
content: It looks like they soldered the collinear antenna directly to the board, but with only a small puny groundplane. That type of antenna works much better with a larger more substantial groundplane.

author: Flo
author_rank: Newbie
timestamp: April 30, 2018, 10:08:13 pm
content: Quote from: hagster on April 30, 2018, 09:52:06 pmGood idea. But i forgot to mention, during sailing, the unit sometimes goes completely under water. So placing the antenne on a higher position would probably be beneficial.

author: ogden
author_rank: Super Contributor
timestamp: April 30, 2018, 10:12:00 pm
content: Quote from: hagster on April 30, 2018, 09:52:06 pmPanel or yagi antenna on the boat which can be positioned at any angle is worst you can do. Just use your head please. Panel/yagi or any other directional antenna on the shore - yes, but not on the boat.

author: Flo
author_rank: Newbie
timestamp: May 02, 2018, 05:21:03 pm
content: I was able to pry the pcb out, and there were no components on the bottom of the pcb attached to the trace.Can i just attach a panel or yagi antenna to the repeater?

author: ogden
author_rank: Super Contributor
timestamp: May 02, 2018, 05:29:31 pm
content: Quote from: Flo on May 02, 2018, 05:21:03 pmYes you can, thou you shall get repeater which have RP-SMA antennas (with RP-SMA connectors) so you can take one off to connect panel antenna. Do not get too excited about yagi antennas, they usually are narrow beamwidth, made for long distances. For carp fishing distances even good omni antenna pair shall be good for sturdy WiFi connection.