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All About Antennas: Radiation Patterns

Heli­um is a gate­way into the world of RF, or radio fre­quen­cy. While the eas­i­est thing to do when you get your hotspot is just plug it in and set it in a win­dow, most of the time you’ll earn far more if you opti­mize a bit. Most of those opti­miza­tions are focused on improv­ing the RF sig­nal your hotspot can bea­con (also called “trans­mit­ting”) as well as improv­ing the abil­i­ty of your hotspot to wit­ness (also called “receiv­ing”.)

I’ll assume you’ve read the piece on anten­nas I wrote that cov­ers some basics. Now, let’s do a deep­er dive into anten­nas and radi­a­tion patterns. 

Let’s start with a zero gain omni anten­na. An omni direc­tion­al anten­na with zero gain will the­o­ret­i­cal­ly radi­ate RF ener­gy in a per­fect globe pat­tern all around it. Now, that’s per­fec­tion. In real­i­ty, most low gain (say, 4 dBi or low­er) anten­nas will do a pret­ty good job, but will have gaps direct­ly above and below the antenna.

The way we “see” an anten­na’s RF pat­tern is by visu­al­iz­ing what it looks like from the top and the side.

Here’s a low­er gain (4 dBi) Bob­cat anten­na’s RF pattern. 

See how it radi­ates out even­ly in every direc­tion to the side, but direct­ly above and below it there are gaps in the RF emit­ted? That’s pret­ty typ­i­cal for an omni direc­tion­al antenna.

Here’s anoth­er exam­ple from the anten­na I use on most of my installs, the HNTen­na. MP Anten­na (the man­u­fac­tur­er of the HNTen­na), puts both pat­terns togeth­er. The Ele­va­tion is what it looks like when you’re see­ing the anten­na from the side (red line) and the Azimuth is what it looks like from the top down (blue line).

All man­u­fac­tur­er’s will have a radi­a­tion pat­tern for their anten­na, and most will share it with you. That pat­tern can change at dif­fer­ent fre­quen­cies on the same anten­na. Here’s an exam­ple of a 3.0dBi L‑Com at dif­fer­ent frequencies.

Now, all the anten­nas so far look pret­ty sim­i­lar even at dif­fer­ent fre­quen­cies, right? They’re all “omni direc­tion­al” anten­nas, mean­ing they’re sup­posed to radi­ate anten­na in all (omni) direc­tions. What does it look like when you get a sec­tor (also called a direc­tion­al) anten­na? Check this out!

This anten­na was designed to radi­ate most of it’s ener­gy in a ver­ti­cal beamwidth of 60 degrees and a hor­i­zon­tal beamwidth of 70 degrees. This is the anten­na you’d use if you were halfway up the side of a moun­tain, with super long views of civilization. 


Antenna Polarization

Next up is anten­na polar­iza­tion. This has­n’t got­ten much press, most­ly because damn near every anten­na you can buy is polar­ized *ver­ti­cal­ly*. In sim­ple terms, that means the RF waves it emit go up and down. A *hor­i­zon­tal­ly* polar­ized anten­na will emit RF waves that go side to side.

Why is that impor­tant? Well, if a ver­ti­cal­ly polar­ized anten­na and a hor­i­zon­tal­ly polar­ized anten­na are try­ing to bea­con or wit­ness each oth­er, they won’t be able to, even if they’re on the same fre­quen­cy! That’s because the “up and down” waves of a VP anten­na won’t inter­sect with the “side to side” waves of an HP antenna.

OK Nik, so why should I care about this? If most of the anten­nas out there are ver­ti­cal­ly polar­ized, I’m fine, right?” Sort of.

See, when that radio ener­gy hits an obsta­cle, it usu­al­ly bounces off *and changes ori­en­ta­tion*. That means a ver­ti­cal­ly polar­ized wave can now be a hor­i­zon­tal­ly polar­ized one. If your hotspot is “lis­ten­ing” on a ver­ti­cal­ly polar­ized anten­na, it won’t wit­ness RF sig­nals that are com­ing in on the hor­i­zon­tal plane, unless…

Here’s the last twist for ya: You can get a “mul­ti” polar­ized anten­na. This allows you to both trans­mit and receive mul­ti­ple sig­nal ori­en­ta­tions. That comes at a cost of a slight reduc­tion in pow­er as the sig­nal is radi­at­ed out on mul­ti­ple planes, BUT…I’ve used a mul­ti-polar­ized anten­na and made 170km wit­ness­es, so it’s not an issue in the real world application.

I’ll fin­ish off with a quick way to think about what anten­na you should buy.

Indoor anten­na — Use the stock anten­na. Get it up as high in your build­ing as pos­si­ble and next to a win­dow. If you MUST buy an indoor anten­na, pick up the HNTen­na indoor version.

Out­door anten­na, urban area, lim­it­ed clear lines of sight — You’ve got a few options. 

HNTen­na Out­door — This is a mul­ti-polar­ized anten­na and what I rec­om­mend for most place­ments. I don’t get affil­i­ate com­mis­sions from that, I just like the antenna.

L‑Com 3 dBi — If you don’t want to spend a bunch, try this one.

L‑Com 6 dBi — Deter­mined to get a high­er gain, but think­ing that 8 or 9 might be too high.

Out­door anten­na, clear line of sight — If you’re des­per­ate for a “high gain” anten­na, try the same one used by the high­est earn­ing hotspot in Boston. It’s cheap and does­n’t test super well in the cham­ber, but works fine in real life. 

Side of a moun­tain — Ok, you real­ly want this? Keep in mind, this anten­na will make you far less in earn­ings if you just throw it up on your house. But since you asked for it, here it is.

That’s it! Now you know a bunch more about anten­na radi­a­tion pat­terns and how to choose the right one for you. Rock on!

31 thoughts on “All About Antennas: Radiation Patterns”

  1. Amaz­ing arti­cle again! Is there any­thing like the HNTen­na for the 868 band?

  2. Hi Nik,

    Is there a 5.8dbi anten­na with mul­ti polar­i­sa­tion or 3dbi will be good even for the sub­urbs where oth­er hotspots are not close

  3. Vis,
    MP Anten­na is work­ing on a 5.8 ver­sion but it’ll be a while. They’re cur­rent anten­na will be fine for sub­ur­ban deploy­ments, just (like very anten­na) get it as high as you can.

  4. Hey,
    Quick ques­tion, if you already get 25 wit­ness­es on bea­con and as high as you can get anten­na do dif­fer­ent anten­nas affect wit­ness­ing or would that be the same?

    For exam­ple with a HNTen­na get more the­o­ret­i­cal wit­ness events than a 5.8 dbi anten­na in an urban setting? 

    Just nev­er under­stood that part. Thanks for the great information!

  5. Hi John, good ques­tion. Depend­ing on how many hotspots you have around you, you may see a *dif­fer­ent* set of 25 with each bea­con. An HNTen­na is like­ly to pick up dif­fer­ent wit­ness­es due to the mul­ti-polar receive. I would­n’t expect mir­a­cles, but every small improve­ment counts.

  6. im cur­rent­ly using a Rak 5.8 in the most opti­mized way I can giv­en my sit­u­a­tion. It appears I’m just on the cusp of a con­nec­tion w/my neigh­bor, as we con­nect, but only rarely. They’re 2.7 miles away. Do you think the 3dbi mul­ti polar might help or should I wait for the 5.8 to be released. Btw, I’ve tried an 8dbi Rak and get noth­ing as I’m in the foothills

  7. Simon Uxbridge

    Hi Nik,
    I have a loca­tion halfway up the side of a moun­tain (2000ft up), with super long views of civ­i­liza­tion and will be using the L‑Com flat pan­el which as you say has a ver­ti­cal beamwidth of 60, and which you advise to aim care­ful­ly. I am look­ing for points on rough­ly how to aim it. Would you think aim­ing the cen­tre of the pan­el at the hori­zon would be too high? CIvil­i­sa­tion starts about 1 mile away from me

  8. Pingback: What To Look For In A Helium Antenna - One Man's Search

  9. Hi Nik,

    If you don’t have direct line of sight due to topog­ra­phy, will the hnten­na help? Cur­rent­ly using the 6dbi from McGill but that doesn’t work.

    Cur­rent­ly can see wit­ness­es far away, but not in the city nearby.

    https://ibb.co/VJJxb1Q

    Thanks!

    Thanks!

  10. Hi Nik

    I’m look­ing at a pic­ture of an ele­va­tion radi­a­tion pat­tern, almost iden­ti­cal to the HNTen­na 915 one above. (I can’t add a pic­ture to this comment.)

    How­ev­er in this pic­ture the 0 degree point is rotat­ed 90 degrees — so that it lines up with the “dip” in the pattern. 

    Could this antenna:
    (1) Sim­ply be the same as the HNTen­na dia­gram (and I’m just over­think­ing it?)
    (2) Be total­ly different?
    (3) Or actu­al­ly be an error in pro­duc­tion of the dia­gram — so in effect the same?

    I hope I have explained this clear­ly? Many thanks. 

    Cheers
    Simon

  11. First respon­der orgs love those because they’re cheap and they “work”, though they’re def­i­nite­ly not the same anten­na as the HNTen­na. Remem­ber, anten­nas don’t real­ly mat­ter that much. Try this one, see if it works for you. For me the cost isn’t a con­cern and I’d rather have the best on the mar­ket, but it *does­n’t make a huge difference.*

  12. Hi Nik,

    Thanks for the more detailed inside of anten­nas. I was won­der­ing what to look for in the specs of an anten­na to know if it will be suit­able for a Heli­um Hotspot. Does it specif­i­cal­ly have to mention/support the LoRa / IOT /Helium tech­nique or will any anten­na that sup­port the 868Mhz freq (I live in the Nether­lands) work? For exam­ple https://poynting.tech/antennas/epnt‑1/ or https://poynting.tech/antennas/xpol‑1–5g/

    Chris

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  14. Does­n’t have to men­tion LoRa/IoT/Helium. That’s a huge band the first one is lis­ten­ing on though, and the mid­dle is def­i­nite­ly not 868 so it’s prob­a­bly not very effi­cient for what you’re doing. 617 – 3800 MHz, whew!

  15. I have seen a hotspot near­by hav­ing a Poynt­ing anten­na in it setup.It’s behind a win­dow on the first floor with a Lon­gAP hotspot. It has a bea­con­ing aver­age of 800–900 times (7d avg) and does 2–3+HNT per day. I was not sure if the poynt­ing anten­na was used for the min­er or maybe a LTE router/modem. If used for the hotspot the MiMo tech­nique seems help pick­nick up a lot of signals.

  16. Inter­est­ing, I’ll check out the Poynt­ing. What’s the hotspot name? Trans­mit­ting 8–900 bea­cons in 7 days is way over the top, you sure that’s not wit­nessed beacons?

  17. Hi, not much info about Hnten­na , you ordered, all is fine ? with new POC i think this anten­na might be a good option, a bit scared to order, I would appre­ci­ate it that you con­firm if they are legit?

    thanks

  18. Hi Jeff, I’ve ordered and deployed mul­ti­ple HNTen­nas. I think they’re the best on the mar­ket, and an excel­lent option for most hotspots deploy­ments. High qual­i­ty, made in Ohio, I’ve been to their man­u­fac­tur­ing plant and met the staff.

  19. Hey Nik,
    Any idea how a stan­dard ver­ti­cal­ly polar­ized anten­na would func­tion if you mount­ed it at a 45 degree angle to the ground? Would it then func­tion as a mul­ti­po­lar­ized anten­na since the waves would be trans­mit­ting and receiv­ing (in the­o­ry) par­tial­ly both ver­ti­cal and hor­i­zon­tal waves and every­thing in between? I’m sure that as an anten­na’s RF is bounc­ing around the world it’s not pure­ly ver­ti­cal even if it’s com­ing from a ver­ti­cal­ly mount­ed anten­na, and as you men­tioned, it seems that in the real world bar­ring your anten­na being in a very flat envi­ron­ment, it seems that RF would be bounc­ing and bend­ing all over the place the fur­ther it got from the anten­na and thus would be able to be picked up by an anten­na mount­ed at 45 degrees.

    Also any idea how ground planes affect a ver­ti­cal­ly polar­ized anten­na? There’s a guy on red­dit talk­ing about how he mount­ed his 4dbi bob­cat anten­na on a bread pan and it increased his earn­ings and oth­er peo­ple said they tried it and it increased theirs too. I won­der if a ground plane is mak­ing the ver­ti­cal waves at least par­tial­ly mul­ti­po­lar and thus allow­ing these anten­nas to per­form better?

  20. Hi Brad, it would prob­a­bly func­tion worse. Mul­ti­po­lar­iza­tion is about mul­ti­ple angles. For the Bob­cat, test­ing in an RF cham­ber has shown that a met­al plate at the bot­tom improves anten­na performance.

  21. Great info on the pat­terns. I have 2 sit­u­a­tions I’m where I’m con­sid­er­ing the HNTen­na and I could use some advice on.

    1. Prairie town, I have the high side about 60’ high­er in ele­va­tion than the rest. 7–9KM to the fur­thest hotspots. Maybe 60–70 in the area and I wit­ness about 30 with a Rak 5.8 on the peak of my house — 500 yards from me sits a giant brick school though. 3dbi Out­door Hnten­na going to pro­vide any benefit?

    2. Host loca­tion low­er plane of the same town but restrict­ed to indoor only with some line of sight chal­lenges and using a Bob­cat stock 4db — Hnten­na indoor 3dbi claims it’s good at over­com­ing some of these chal­lenges — thoughts?

    Have no issues spend­ing the $ to find out but McGill is also in my considerations..

    Thanks,
    Mike

  22. Hi Mike,
    Always hard to say that one anten­na will always do super well. I’m putting HNTen­nas up even on my moun­tain installs now. I don’t think you’ll see a huge improve­ment over the Rak, though you may see a slight one. The HNTen­na indoor is sup­posed to be excel­lent, but I haven’t installed it indoors. I’ve seen it work well out­doors. You won’t go wrong with any of those anten­nas listed.

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