Moxon Antenna. RCHacker #49
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- Опубликовано: 14 окт 2024
- DIY build and simulation of the Moxon antenna with 4nec2 software. Not a bad choice for long range FPV work on 433Mhz. Also it is simple and cheap to build.
Moxon design software.
www.moxonantenn...
Simulation software.
www.qsl.net/4nec2/
Interesting articles by VE2AZX
ve2azx.net/
My designs files on github.
github.com/rch...
Kind of like a yagi ? No the Moxon is a Yagi ! To be more precise a Moxon is a 2 element yagi that uses capacitive end coupling instead of lossy inductors as a means of reducing its size while maintaining an acceptable input impedance.
By using capacitive end loading the moxon achieves a much greater radiation efficiency as compared to other designs which use lossy matching networks and inductors to reduce the size of the antenna. The bottom line is the moxon is a very highly efficient short boom 2 element reduced size yagi.
If you're a ham this is important because a mono band Moxon yagi will easily outperform a trapped triband yagi at a fraction of the cost and weight.
By the way nice work on that little moxon.
you can tune the driven and the reflector by hanging a wire from one of the corners on each element, then trim the wire to tune. Use field strength meters or VNA to fine tune.
Cheers. My obsession with RF is putting other projects on hold, but once done I will have all the range I will ever need.
Built the Moxon and turnstyle tonight. Much better. getting about 850m on the ground so far. Will put it in the quad and do some range checks.
Thanks again :)
I can absolutely confirm this antenna is a monster for long range. Previously with my Nagoya N77 at 3.5 miles I was getting RSSI readings of 60-70%. With the Moxon I threw together last night, at 5.3 miles I was still getting solid, unwavering 100%. My only reason for turning around was concern for my battery.
I had it angled on its side for vertical polarisation and the RX antenna was a home made dipole.
Thanks so much for this video, the Moxon is an incredible antenna!
Awesome, great to know that it worked for you.
I know it is not statistically significant but I have now had two FRSky D8RII+ receivers fail in exactly the same way. (drastically reduced range). So I am now moving to openLRS. There is a learning curve, but worth it for more features, better range. I get a lot of help requests with what sounds like bad units from HK, So I would get them from DTFUHF.
Stick your crosshair out the back of your quad on a bbq skewer.
Awesome Mark. Found this over at Flitetest. I always look forward to your videos.
I made a moxon for 435 mhz for the orange tx and i love it in combo whit a turnstyle on de plane very stable connection thanx for the tips cudent have done it whit out you vid
The way you have it mounted is vertically polarised?
It is all to do with the wire lengths, the generator programs calculates everything for 50 ohms, so if you are good with your measurements you are probably alright.
IBCrazy did a tutorial on rcgroups for making your own SWR meter, but measuring the impedance directly requires more specialised equipment.
Great vid Mark! Built this antenna and used it on my 9XR TX (Orange LRS tx) and turnstyle on my wing (Orange LRS RX). Noticed that separation between reflector and tx really makes sense. Got 1.5 miles and over 50% RSSI left;-)
Hi Marc, enjoying your Videos. Have just built my first Moxon Antenna, using the end foam panels from the box that my Bixler 2 arrived in from Hobbyking. They were precut and the perfect size for the project. I just want to know, would it affect the performance, if I used the second panel, laid flat on the now completed Antenna, thereby sandwiching the Copper Rectangle in between the 2 foam panels. Then cutting away the excess foam, so that it ends up looking like a professionally made Moxon Antenna? and then spraying the whole thing Black. I find all of your Videos great reading, and have read some of them many times, so as to familiarise myself with some of your methods. While I wait for my new Turnigy 9xR and 433 modules etc to arrive from Hong Kong. Also invested in a Raptor V2 to put it all in. I am now a retired Pensioner living in Spain, where I also enjoy countless days of ideal flying conditions. Please, keep up the great work.
Cheers, I cannot say for sure but I doubt you will notice the difference. The dielectric value for polystyrene is very low so I have assumed it is negligible.
RCHacker I agree that helical is the way to go, put it on a tripod and know what the azimuth is of the aircraft. Most important Elevation may be optimum at a certain point depending on terrain. Helical you might loose the gain that Horz. provides. It is simply known as ground gain. Ground gain can not be achieved with vertical orientation. From all that I have read and observed. KB3IUL
If you had 3 of them with a diversity setup it would work great, but only 2 antenna diversity systems are available at the moment.
OpenLRSng however may be heading in that direction.
Until then you are better off with an omni directional antenna like the turnstile or vee on the receiver.
Yep. Orange OpenLrRs. I have send two sets back. This is the third and the last attempt. Was sure I would get there with these antennas.
(are you an Oz expat?)
I have been having terrible range issues with Orange LRS. Have tried the v and sander styles. Looking forward to building this to see if it fixes the issue,
Thanks so much for all your tutorials :) They are appreciated.
you can also boost your tx power by using a wifi amplifier, just choose the correct frequency version and get the correct sma adapters, i put a largish lipo and a dc dc converter in the tx which is large enough to drive the wifi amplifier, the wifi amplifier happens to fit under the handle on the transmitter.
Have not tested in practice yet but it should be much better.
Great way of tuning an antenna. Thanks for sharing it with us.
How do you make sure the feed point is 50 ohms?
That was an incredibly awesome video! I do thank you very much for your tutorial, and hard work that went on this video....
Not something I have taken into account and really hard for me to test, perhaps I can try cutting some of the foam away at a later date. The wire I am using has enamel coating but I like that as it protects the rf front end from static. Relative to air enamel has a dielectric constant of 5.1 but it is a very thin coating. Silicone RTV 3.6, Poylstyrene 2.5 (this might be the value for solid, the polystyrene I am using is mostly air).
Surprisingly balsa has one of the lowest values at 1.4.
That is really good to know. Of course I still need to test it but it looks like I have more range than I will ever need.
Now to work on the video system.
Hi, i cant decide between open lrs and FRsky. Frsky because i have heard it is very reliable and has rssi downlink. Do you think the orange lrs has reliable signal? Also i need good rssi or i will just worry about losing signal and not fly very far. I have a quadcopter i want to use it with; jason from ilovetoflyfpv uses a turnstile on the bottom of his wing but that wont work for my quad. What are the anntena options for a quad?
And finally i need some opinions: FRsky or LRS?
thanks in advance
I use the spreadsheet based editor. Not the easiest but the most powerful as you can incorporate equations into your design.
RCHacker, great video... Im learning a ton from you!
Do you think one could build a Moxon using PCB material as the structure and element using a home CNC machine? I could get the dimensions near perfect, but was unsure what to use for wire size in the calculator... or if it would even be worth trying.
Cheers, I don't think pcb material would be ideal, it has a larger dielectric effect than foam or balsa.
Are you thinking cutting everything away except the copper? Might work, but would be best to simulate it. Unfortunately that sort of simulation software is expensive.
Hey thanks for the reply! I would have cut everything away and probably the entire center leaving only a frame and the trace for the elements. Might be worth an experiment :)
It is best to power off any other modules and remove close antennas.
the 4nec2 looks very interesting, what program do you find best to use to sketch out antenna designs? obviously the moxon generator does an output file but what about the turnstile, v's etc?
Not sure about the sander style they are just a monopole. They seem to work best as a pair on a diversity receiver which makes it more like a vee. Using just one is a mistake.
The units do perform, but run a bad antenna or none at all they could get damaged.
thanks for video. questions - Is there any specific length of the rg316 that you cut it to? Or did you just cut the length to fit your mount to the radio?
Nope just what I needed. Everything is matched so the lengths should not matter.
Mark,
Does the foam plate or hot glue have any noticeable dielectric effect on performance at 70Cm?
Alan
@Eepos Angle Try the vee, www.rchacker.com/diy/antenna-designs-for-rc/vee-antenna I have measurements for 459 there too as well.
Hi, are you going to do a range test on the moxon?
A bit more searching found a reference for styrofoam at 1.03. So if I drop the enamel wire and use a glue that foams up the effect should be almost nil.
Thanks for the video :) Would it be possible to do one on a multi element yagi?
also i agree with jchelm1979, omni directional antenna's can get 10km. I have been just over 10km with homemade 1/2 wave dipole tx, turnstile rx. Have you seen the 37km effort of diegojjd?
Tried the Moxon and Turnstyle - slightly better range but still only 500m at 50m high before failsafe kicked in. Was getting about 850m on the ground in testing. No idea why I cant get range out of the Openlrs
How are you finding it compared with the V antenna you made a while ago?
Thanks. Will do, I am a bit obsessed with RF at the moment.
Wider beam width, less 2db gain and horizontally polarised. Probably much better SWR and better overall.
Thanks for this video! I will try to design some custom antenna's for my rc link (2.4Ghz FrSky) and i will definitely take a look at your experimental designs.
As an electronics guy rf is like black magic to me and i would like to learn more about it, antenna design will definitely help me explore that world.
Nice video, although I will point out that you should easily get 10km on 100mw without directional antennas I have been to 8.1km with over 55% RSSI showing on my OSD and only turned back as I was worried about battery consumption and I still had good video using 5.8Ghz I had a diamond srh771 on the Tx and a home made dipole on the Rx I was using flytron equipment and the firmware was before the NG stuff came out so was using Thundead which was the predecessor.
hay thanks for that video ill be doing one my self , but on the plane what kind of antenna is needed
Hello witch windows emulator are you using?
can you make a video of all the proses of the open lrs and how to do any step ? pleez
Mark,
Excellent video - thanks for the resources.
Alan
hey Mark!
Great Video. Thank You for sharing this!
im owning a MAC for my business. I love it.
But why are you using mac for RC-Stuff? . The most Opensourcetools for programming are avalible for Windows. I often hear you crying that some hardware is not running good for mac.....
Incorrect, most open source programming tools are for linux and MacPorts gives me most of that. Anything that does not work for me I just run under a virtual machine or with wine. Right now thats just 4nec2, and the ardupilot software.
Mostly I use it for video editing anyway.
I spent 3 years of my software engineering career programming for windows, and its was a nightmare, never again.
RCHacker
ok. thats why you stopped your programming career and use mac os.
ok ok ok! i was wrong! Linux is the plattform for the most open source.
Half of my usb-devices wont work on mac osx, i feel more flexible on windows 7.
What do you think about making a tutorial, fixing burned ESCs?
I did not find a lot of informations about this.
muddanundvoddan lol, us nerds get passionate about our platforms. I have a draw full of burned out ESCs. If you have the push on programmer they make nice mini arduinos. Re-soldering mosfets I find pretty hard.
RCHacker
come on mark! you have a new rework-station and a lot of stuff i dont have. Show us a "how to repair a burned out ESC in a quick and easy way!" We can get a 100-pack of mosfets for 20 $ on Ebay to repair our 30 $ ESC.
"Never buy ESCs again" could be the headline! What do you Think?
But Hobbyking will hate you for that. For sure!
Dont worry about a virus behind that link => you have a MAC!
www.ebay.de/itm/100-PCS-FDS7764A-SOP-8-FDS7764-7764A-30V-N-Channel-PowerTrench-MOSFET-/301232124838?pt=LH_DefaultDomain_0&hash=item4622d573a6
if you like i order a pack of nfets and other parts of your need to do this tutorial and support your work.
Just made one. Thanks for all the invaluable info.
OMG. Huge increase in range over the RMILEC UHF435MHz SRC771 1/2 Wave Length UHF Antenna from Hobby King! I haven't flown my antennas long range yet, but line-of-sight on the ground, the RMILEC antenna did 0.97 miles and the Moxon just did 1.97 miles (3.17Km) before I ran out of straight road. That verifies the range is at least doubled over a traditional monopole antenna. Details: OpenLRS 1W with no telemetry at 4800 baud.
Additional details: Used all the tools mentioned in the video to design and model. I cut up an Ethernet cable and took the conductors out. 24AWG wire and easy to solder. I did use a ferrite toroid as well with three turns.
casual_user Thats great, thanks for posting your results.
Very nicely done, informative, entertaining and refreshing subject well researched.
ricci
Excellent video.love your tutorials.make some more about antennas. Thank you and keep up good work.
Should not be a problem as it crosses at the antinode. Think about yagi with elements shorted to the boom same thing
Sweet, thats good to know.
from its radiation pattern it will will benifit us more verticaloly polaized, we have more propagragtion on the horizon. front and sides, ham use horizontal for directional purpose and will be hard for ti to be mounted vertically with such large antennas for HF and they need it to bounce in the ionosphere.for us we need direct line of light and we are vertically polorized in the receiver to give it omni direction in the model. we would not mount model antennas horizontally or it will be directional not omni in reception.the propagation pattern when vertically polaized will give more horizon in front from left to right and null behind, i like this antenna.tnx for the video design.
You mention that the wire should be as thin as possible, would foil strip work?
bridgendesar That makes it into a plane which would need to be modelled differently. If you don't have thinner just put what you have into the calculator.
Yeah I am hooked. Feel free to contribute to my antenna repository on GitHub.
will this work for a video Rx antenna?
Oh dear the antenna bug really has bitten hard :) Apologies for leading you astray but I did warn you of the possible consequences. Performance antennas are probably the best bang for buck thing you can do for any RF system.
A couple of observations. You say putting a reflector on the Moxon did little to enhance it. That's because so little RF energy is present behind the existing reflector. If you look at other designs like Yagis, cubic quads etc you will notice they only ever use a single reflector for this reason. On the other hand you will see further directivity improvements by adding a director element in front of the feed plane since this is where the RF feild exists. I'd start with similar spacing and length ratios employed in Yagi designs and the refine the design from there. For a more robust Moxon design Have you considered using PCB and etch the elements? As to the impact of any dialectric effect from the styrofoam I'd expect very little change at the relatively low frequencies around 70cm as the foam is basically mostly air.
Another little gem you might find interesting is by mounting two normaly linear polarised high gain antennas at 90 degrees to each other and feed them 90 degrees out of phase you get circular polarised radiation. To get the 90 degree phase shift simply feed one antenna directly and the other via a 90 degree delay lenngth coax connected in parallel. By changing which antenna is connected first determines the rh or lh polarisation. I used this method while messing about with satellites. Don't forget to factor in the coax velocity factor when cutting the delay coax and also the now paralleled individual feed point impedances. Obviously this arrangement will be of no use on the handheld transmitter but could prove useful for your FPV ground station at long range.
Nice to confirm on my assumptions with the foam. Know any cheap PCB RF simulation tools? I looked into it, I think I am done on that.
I have to admit I am no expert, all my RF knowledge is what I assimilated when I was an active radio amateur. Having said that I can offer a few generalisations.
As the length to diameter ratio gets smaller ie fatter wires, so the theoretical length will decrease. So I suggest you try to duplicate this with on the pcb say 0.5 - 0.75mm conversely the wider track will yeild a wider bandwidth at the cost of gain.
As the PCB trace is in close proximity to a dialectric different to free space again the length will be affected from theoretical values based on antennas in free space. If you know the composition of the PCB ie G10 then you should be able to find a compensation factor from references or perhaps an online calculator. Failing that It would be possible to make a wire mockup and attach it to a bare piece of PCB substrate material ie no copper, then test with a SWR bridge to find optimal lengths. You could then confidently reproduce this as a PCB.
I would recommend you try to find an active radio amateur for assistance as he/she will most likely have the required tools and experience to get a working antenna.
this all assumes the frequency of interest is in the UHF range where dimensions are less critical and equipment cheaper than for say 2.4 or 5.8GHz. Making an antenna for such high frequencies is bound to problematic.
As for the SMA connection, your idea should work well. just be sure to mechanicaly support the antenna to prevent damage to the radio.
Wow, sorry, originally I only read the first point of the post. So you could have a CP moxon that would look something like a pinwheel.
The nec software is really only made for simulating free air antennas or large antennas near the ground. There is other software out there for PCB antennas but is is very expensive.
PCB manufacture is pretty cheap these days, if you were going for 5.8G or 2.4 I would make a bunch of slightly different ones on the same panel, cut them out then just test them all.
extra extra read all about it
sv1bsx.50webs.com/antenna-pol/polarization.html
Been a little quiet of late Marc hope all is well
Hi! whats the best match for this antenna on the Rx? I have a moxon on my Tx and a dipole on my Rx. but the max range im getting is only 2.5km on my 100mw module.
That should be pretty good, try changing the orientation, perhaps location.
and how should i have it mounted? Vertically or horizontal? I have it Horizontal at the moment both Moxon and DiPole. will a Turnstile on Rx increase my range?
Ian, please can you show me some schematics connection of the mathing and fasing lines, i'm getting crazy, i use 33'9 cm of 75 ohm rg 59 for matching, and 51,3 cm 50 ohm rg 58 for fasing line, for vhf ant, but ant not in resonance .. please help me
Thats kind of hard. There are not any places flat enough here to do it properly. I have done the homework and theoretically the range could be hundreds of kilometres.
I will probably just test it at 1mW then go fly.
So how much range have you/people got with the Moxon antenna?
I mostly fly amongst the trees in a humid environment so cannot really say, but it is more than enough for me.
A vee or turnstile is a good match.
Good question by the way.
cool, for UHF LRS
435mhz :(
thanks for the software.. :)
More like hardware emulation. VMWare fusion.
HobbyKing....
Great video Mark as always.
I would reduce the tightness of the wraps around the ferrite choke as they are way to tight and will be severely effect the output from the antenna. You can just use a whole tone of them in series to reduce the space and annoyance of coiling the feed line through the choke.
Thanks, thats a great idea.