Plantenna: the plant antenna

The back story behind [Mike] experimenting with plants as AM radio transmission antennas antennae is rather interesting and worth the short read. But for those who just want the facts, [Mike] took an ATMega324, modified the PWM output into a sinusoidal AM signal (using a simple form of RLC circuitry), and connected the circuit to a plant no plants were harmed in the making of this project. The results? Well we’re not ones who would spoil the surprise, you’ll have to see for yourself in the video after the jump.

Comments

  1. Timmah says:

    Rush Limbaugh finally goes green!

  2. mess_maker says:

    That’s funny :) He is on 540AM here in Central Florida… is that where you are, Timmah?

  3. gottabethatguy says:

    What does this prove? The video doesn’t show nor explain anything, neither does the article. How do you know that the signal isn’t being transmitted by the wires with the alligator clips attached? I’m going to go RTA but as of this moment none of this proves anything or even makes sense.

  4. gottabethatguy says:

    “As I mentioned, the “plantenna” did slightly improve reception. However, the effect was admittedly quite small. My fingers actually had a greater impact on the signal’s strength than did the plantenna.”

    The above is taken from the article. Looks like I was right, nothing has been proven. He didn’t even provide a scale other than what he perceived as an improvement to show the actual increase in signal reception. I’m willing to bet my coffee maker (and I love my coffee maker) that the plant has a next to negligible effect on the transmission and that the bulk of the transmission is being performed by the wires the alligator clips are attached to and the device itself.

    Up next peopletennas, pie platetennas, and pennytennas.

    All of those were things I used when I was 8 to bring in CTV a little clearer on the farm since my bedroom didn’t have access to the outside antenna. TV check, coax cable plugged in check, place penny on end of coax check, enjoy late night tv.

  5. Thioden says:

    Interesting, but I would like to see what happens when he unclips the plant. It looks like he is using a rather long lead to connect to the plant. I think the wire might be acting as an antenna.

    Still, it’s a fun idea.

  6. Andrew says:

    I don’t get how this is a hack. If I stick a coathanger on my transmitter, can I be on the front page too?

  7. arocholl says:

    Two interesting mistakes in the article:
    1) An RLC circuit doesn’t amplify a signal, as he apparently states (” it actually provides a slight amount of amplification through resonance between C1 and L1″). RLC is tunned and thus it is selective though, where it will attenuate some frequencies more than others, and that is what he displays on the plotted graphs. But saying it amplifies is no sense. Note these are pure theoretical graphs, simulated and not taking account parasistic impedance nor many other important aspects by which an actual frequency response of his circuit will be different to what he plots out.
    2) More interestingly, he has the transmitter and receiver very close each other, much closer than 1 wave length, which means he is capacitively coupling transmitter and receiver. So this is not radio transmission, as the antenna doesn’t work as such but as part of a coupled capacitor. He should move receiver significantly further away at this frequency to start talking about radio.

  8. Oren Beck says:
  9. Bosman says:

    You can get the same results, sticking calculator to FM radio :)

  10. guy says:

    Few years back i did some tests with 2 meters, 70 cm bands of amateur radio. I wanted to see if i could build antenna out of junk that could be used in an emergency – i happened to also have an SWR meter that let me fine tune them, but math and trial and error could work just as well. Anyways, dipole antennas made from gum wrappers, golf umbrellas, and a plane metal hanger bent into a quad all got me to my local repeater, so at least 10 miles, didn’t have a way to test actual field strength. Long story short, you would be amazed just how many things work as antennas, even i ntheir unaltered state.

  11. gottabethatguy says:

    What does plant perception have to do with using a plant as an antenna to transmit a signal? You need to read the article.

  12. Fallen says:

    Agreed with arocholl.

  13. biozz says:

    wont give your plant cancer like the new iphone? XD

  14. fartface says:

    Wow HAD and the experimenter are “dumb” in the ways of RF…

    The wire and the alligator clip are the antenna. Epic Fail for an article.

  15. Richard says:

    Returning for a moment to more authentic antenna shinannegans, it’s surprising what can be made to radiate effectively… and possibly less surprising that quite a few radio amateurs have a little bit of light-hearted fun with the idea.
    http://www.n0ew.org/k0s/k0s_2009/k0s_2009.php will offer a few seemingly daft ideas to tinker with… but you never know what you might have to get on the air with in an emergency so there is a point to the silliness – sort of. ;-)

    73

  16. Velleos says:

    I think it was worth it to post, because it’s getting everyone talking. This may get more people interested in how antennae work. It did for me.

  17. Necromant says:

    Hmm… just imagine: hackaday, year 2024:
    Mike finally released his hack: the genetically hacked plant acts as a wifi antenna. He managed to grow it up to 17dBi, until the frequency shifted off, what he considers a success.

  18. Necromant says:

    Now seriously. You’re better off with some cactus: the resistance if you plug the multimeter probes in it is about 60-80k (distance is about 3 cm between probes. The next step is to wisely chose the watering, since some article I read spoke that some substances found in soil affect the resistance.
    Then may be we can hack some bush to be a wifi antenna =)

  19. gottabethatguy says:

    @Velleos By that logic posting
    “Arduino Rules, bababooie bababooie” would be a good article.

  20. Mike says:

    Hi Guys,

    Thanks for the comments! Just to clarify, based on some of the comments I’ve been reading on HaD…

    First, no, I’m clearly not an expert on radio transmission. Not even close. I can really only tell you what worked and what didn’t. I don’t have any RF instruments so I can’t quantify any of the results above. All I can say is that with that alligator clip connected to the plant, reception was improved qualitatively. With the clip disconnected (but the wire STILL attached to the circuit), reception was not quite as good. But again, it was a small difference. With regard to the RLC circuit, no, it doesn’t amplify the output power. However, it does amplify the voltage at the antenna. That’s the resonant nature of this RLC circuit. Granted, not all RLC circuits are resonant (underdamped), but this one was designed to be.

    Anyway, I hope you’ve still found something here interesting/useful! My apologies if I’m wasting your time. If you’re really curious about this circuit, build it and tell me what happens. Thanks!

    -Mike

  21. crazy_conspiracy_man says:

    not a hack

  22. Roder says:

    I use my dog as antena!

  23. Chris says:

    Lighten up folks, it’s just a fun experiment.

    Though a more meaningful (and simpler) test is to use a plant as receive antenna for a distant station.

    Back in my early years, I had a high-gain JFET amp and speaker hooked up to a plant to try and detect the “paranormal plant perception” Oren mentioned. I never found any proof of the phenomena. The only odd result is that it consistently produced an audible signal when a car pulled into my driveway. Though I never figured out exactly why, I believe it’s just science, not the supernatural.

    BTW, you can get a much better connection to a plant by driving a conductor into the soil, like a large nail. Make sure the soil is moist (doesn’t have to be saturated) and properly fertilized (the chemicals salts enhance conductivity); both of which should be the case anyway. I’ve used this to connect ionizer modules to houseplants, in order to train cats not to treat them as salads. A few harmless static zaps and they never mess with that plant again.

  24. shiona says:

    It is antennas.
    A quote from wikipedia, not a reliable source blaablaablaa, but I believe most of you know this to be true:
    “In the context of engineering and physics, the plural of antenna is antennas, and it has been this way since about 1950 (or earlier), when a cornerstone textbook in this field, Antennas, was published by John D. Kraus of the Ohio State University. Besides the title, Dr. Kraus noted this in a footnote on the first page of his book. Insects may have “antennae”, but this form is not used in the context of electronics.”

  25. strider_mt2k says:

    So you guys posted THIS, but not my simple robot made of industrial scrap??

    dayam…I should have connected it to an AM radio.

    :(

    Aw screw it, check it out!
    http://www.flickr.com/photos/strider_mt2k/sets/72157625069322244/

  26. Jakob Griffith says:

    @strider_mt2k:

    I’ll begin with the usual “we can’t post everything, we try and have a mix of complicated to simple, and fun to crazy, and old to new.”

    A lot of thought actually went into posting your industrial wonder. In the end, it was decided we would wait for your reply email and/or the “planned updates” which we figured wouldn’t be more than a month away. Eventually though, it fell off our stack of “we’ll wait on these” into the “never showed up, it can’t really stand on its own” pile.

    For the “never showed up” part, I can’t seem to find a reply from you in our inbox. It may have been deleted, you might have only sent it to Caleb (in which case, the rest of HAD team can’t possibly feature something they don’t have!) or otherwise. While we don’t advocate spamming our tip line, you /can/ resubmit an idea; sometimes we just miss things.

    Elaborating on the “can’t stand on its own” part. There is some significant difference between this Plant Antenna article by [Mike] and your flickr stream. Mostly being, Plantenna by [Mike] was a very well written thought out article that was clear, detailed, had pictures, and other support. On the contrary, you simply posted a series of pictures, which while /we/ at HAD may understand what is going on, others might not.

    In short, for anyone who wishes to be featured on had, take the following to note.

    http://hackaday.com/2009/09/19/how-to-make-your-project-an-internet-sensation/

    Jakob Griffith
    HAD Team

  27. jeditalian says:

    gucci antenna. gucci gucci antenna.
    i built an antenna out of a 133mhz pentium, a 400mhz amd k6 or something, some duct tape, copper wire, and an 80mm fan grill. i don’t have to water it and it does a damn fine job of picking up the DTV. i tried hooking up some transformer coil but it just fucked up the signal completely, even when it was nearby, and the computer parts were the only decent materials i had lying around that might possibly do the job. back in the day you could get by with some wire, maybe a coathanger, aluminum foil, but nowadays you gotta throw something funky in the mix. most of my experiments involving electric wires and plants ended in dead plants. except my tobacco plant, which was growing through hard drive platters and had magnets attached and couldn’t support its weight without copper wire until i moved it outside a year later, where it got huge as a tobacco plant should, and is now dead because i didn’t go collect the yummy worms off the leaves. i think you would have very good results with a cat, however. they lay around all day and if you made it a metal cat-mat (aluminum foil, perhaps) and connect it to an antenna wire, it should have the same effect as when you touch the antenna with your finger, using your bodies capacitance or whatever. or a snake. you can give the snake a body piercing and connect the wire to that. that would be a cool antenna.

  28. Harvie.CZ says:

    Imho the most interesting part of this project is using AVR as RF modulator. i’ve googled a bit and i’ve found this:

    http://jonnyblanch.webs.com/arduino.htm

    Arduino+Wire = RF transmitter

  29. gottabethatguy says:

    @Jakob Griffith, Judging by your teams editing and choice of articles sometimes I’m not so sure you or your team “understand what is going on”.

  30. Samuel Clemmens says:

    You know, after they were able to draw electrical energy by tapping the roots of trees, I contemplated the thought of using them as antennas.

    It turns out that this has been a concept known and tested, and found to WORK as far back as 1909!

    Here’s a PDF link containing 4 documents researching the success and works.

    http://w5jgv.com/tree_antenna/Robert%20Hand.pdf

    The root of that folder also details this gentlemans own work with tree antennas, and has lots of pictures, including a pre-amplifier build into his ‘tree reciever’.

    Just thought I’d share the fact that this is something that has a future possibly, and I for one plant to go for it.

  31. Oren Beck says:

    The slick presentation or crude lab notes versions of the hack itself should not deprecate the MERIT of anything considered “a hack” Making us rethink old presumptions counts for a lot.

  32. strider_mt2k says:

    Aw Caleb you’re breaking my stones now…

    It just figures I had to put all my robot stuff away for a HUGE V.I.P. visit at our facility.

    I have to decide if it’s worth it to pursue building this kind of stuff specifically BECAUSE it’s so derivative, but if you edited all the derivative stuff from here you’d have at least a third less material! ;)

  33. gottabethatguy says:

    Samuel Clemmens

    That article states that a dead telephone pole worked better than a live tree. I bet a coat hanger would work even better. And they state the the tree itself wasn’t used to transmit rather the antenna was wrapped around the tree.

    I’m betting there is a reason this train of research was abandoned by the military. I actually found and read two of the papers cited in your one page PDF (which provided no info of its own I might add). I’ll sum up the conclusions of each for you.

    Trees suck as antenna’s use a real antenna. Uniform DEAD telephone poles perform better as a toroid. Want to know what works even better….. real freaking antennas.

  34. strider_mt2k says:

    @Jakob Griffith
    Excellent point well taken.
    I will look towards expounding upon the next project!

    :D

  35. Mike says:

    FYI, the original article can now be found here: http://www.nlvocables.com/blog/?p=312

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