Ground plane question

I’m pulling together ideas for a base and rover system. Im thinking about using an upside down cooking pot purchased at the local dollar store. Ya, I know it’s weird. But so am I.

The flat base of the pot should make a good ground plane and the pot being upside down provides water protection for the M2 and LoRa as well as adequate airflow for cooling. I could install a small piece of screen to let the air in and keep the wasps and spiders out. The radio and M2 could be held in place by zip ties installed through small holes drilled in the sides of the pot which are then plugged with a dab of rtv. Alternatively, I could make bands of thin sheet metal screwed to the pot to clamp them in place. If the pot is thick enough, I could tap the holes for removable machine screws. I had also thought the LoRa radio antenna could be attached directly to the radio and hang down below the pot - the pot might protect the M2 from radio interference.

So, the two questions for now are:

  1. Is a ground plane ever NOT a good idea?

  2. Would the curved edge around the bottom of a pot affect the performance of the ground plane by reflecting signals coming from the ground? In other words would I be better off with a flat plate with an upside down plastic bowl under it instead of a pot with curved edges?


I don’t think you really need a ground plane for the helical antenna. I like you design and thinking process !!


I made one for my M2 off some recommendations I found somewhere (Sorry, forget where I saw the data). It said around a 10cm ground plane. I made one from 1/8" steel and mounted my antenna on it. To be honest, I didn’t see any real gain with this.

Hi John,

Helical antennas can show robust performance without ground planes.

The unit can hardly be provided with enough air for cooling in such a setup. We usually recommend providing Reach M2 with additional ventilation to prevent issues with overheating.


HI Bryan, I had seen before that a ground plane probably isn’t needed. That’s why I asked the question the weird way that I did. Reworded a bit, the question is: if I use one, will it hurt? Basically I’d like to make a solid open weather proof enclosure. But I don’t want to “hurt” performance. As far as know, I have plenty of signal. I just don’t want to lose any of what I have. A base that looks like a ground plane to the antenna seems like the best way to deal with the weather issues.

Hi Kseniia, as I have mentioned, I don’t really need better antenna performance. I am really after weather protection. It seems to me that a ground plane is a great platform for creating a lid for the electronics mounted underneath it. By using an upside down pot I get side protection too. So I just want to know if such a ground plane will HURT performance.

As far as temperature goes, I cannot see how an upside down pot would really get much hotter than they would in the open air. After all, the pot is WIDE OPEN on the bottom so air can easily circulate around the M2 and LoRa units attached to it.

The other significant difference is that I plan to cut the sides of the pot shorter than how it appears in the photo I shared. Probably only 5cm or so high. Therefore, my pot will look at lot more like a frying pan than a pot.

That is the dimension given in Emlid’s user documentation. See the bottom of the page at the following link:

In direct sunlight I bet it is 5 to 10 degrees F higher in the pot due to heat absorption with the black metal surface. Heat rises and the pot would catch it.

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Ah yes, I neglected to say that I plan to paint the pot John Deere Yellow. I’m also thinking of adding a thin foam liner for temperature control and vibration dampening.

I expected someone to mention the heat rising effect… Thanks for not disappointing me! :wink: But I doubt that will matter much given that it will be mounted on a moving tractor. I’m pretty confident that any amount of breeze either from the wind or the moving tractor will constantly scrub out the air in the pot.

In any event, it has to be superior to any other kind of enclosure that I can envision except those that include a fan - which wouldn’t work in moist conditions.

I’ve gotten good results with my mount with no ground plane. PP a 1 hour observation on known NGS passive control mark with the helical and horizontal and vertical was less than 3cm. I’ve since switched to the Harxon GPS 500 antenna because it’s in NGS antenna database.

Are you sure you don’t want to go with CNH red? :wink:

I was assuming it was going to be a base station since you stated in the first post base and rover. On the base the yellow would definitely help.

Since you have JD, perhaps you can find some old ITC globes rip the guts out and add a M2 system. The ITC is coming on end of life.

Too funny. My neighbour drives red. We constantly joke about his red and my green.

He wants to borrow my system when I get it going. I can’t wait to see his face when he sees the green and yellow…

No need for ground plane with the helical M2 antenna works just fine without it. Though its pretty hard to spot on top of the tractor cab. The M2 itself keep it in decent size enclosure it gets rather hot, I use Velcro command strips to stick it to were its needed . Currently my base resides in a 7.62 Nato ammo can.

For Ag using the M2 Helical has one large advantage it sheds dust rather well, have not had to stop to wipe it off it ever. The flatter globes are usually good for a wipe off every 12hrs or so.

ITC still can work on WAAS for the foreseeable future thanks to Agra-GPS 's ITC extend converter. It masks the WAAS data as SF1 and it continues to work with auto steer.

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It seems everyone is misunderstanding my question. So I have obviously failed at asking it correctly.

My question is NOT "Will a ground plane help? ".

My question IS “Will a ground plane hurt?”.

I want the pot to serve as an open enclosure for heat control and for weather protection. But I don’t want it to hurt performance.

If the pot style of ground plane will hurt performance of the antenna, then I will switch to a plastic housing of some kind - sort of like a margarine container.

I like the idea of using a small aluminium pot because it is light, structural, and inexpensive. It can be machined, it can be drilled and the holes can be threaded, etc etc.

Anyway, the question for this thread is: Can a ground plane with a sloping rounded edge at the OD HURT performance of the antenna?

All good stuff. Thanks.

As of today, I have no plans for autosteer. I just want guidance for manual steering. In time, that may change. But for now I am quite happy looking forward to guidance.

I have no ITC now so I don’t miss it. I’ve never seen the hardware at a scrap yard. I’ll keep my eyes open.

Yes, I do want it for both base and rover. Both need weather protection. I plan to mount my base up near the house which is on a hill. It’s almost always quite windy there.

I’ve never seen an ITC at a junk yard around here. But it’s a great idea. I’ll keep my eyes open.

I wasn’t aware that something came out for the ITC. If not, there are a lot of them out there.

Ground plane wont hurt the signal at all.

The Rf connector is plenty strong enough to hold the antenna, unless you plan on crashing it into something.

I know your not into auto steer yet. Light bar will improve row straightness a lot. But no human can out steer even the old L1 guidance units. We just do not have the attention span.

It looks like you like to tinker. You should check out Ag Open GPS. Even for light bar guidance it is extremely reasonable.

Thank you for that info and more.

Yes, I like to tinker. I did a quick check of AgOpen and bookmarked it. I’m sure I will enjoy learning more when I am done this phase of my project.

For now, my goal is to build a manual guidance system to use with spraying, fertilizing, and planting for this coming spring. I used an android tablet program (Field Navigator) last fall with the GPS built into my phone. It worked but not well enough to get rid of the proverbial orange guidance flags all over my fields.

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