i’ve had good success with this one. its not very compact but i did check its performance with a NanoVNA and it actually lines up with 915Mhz, unlike the stock options that come with the board and seem to be meant for 868Mhz
30’ doesn’t sound right. Ive tested a tbeam with a 50ohm dummy load on it and get better range than that with just PCB leakage.
Maybe your board/antenna has a problem. I would check for damage, missing parts, cold solder joints, etc.
Have you ever had the tbeams powered up without an antenna attached? Like when testing the software after flashing them?
I haven’t powered them up without an antenna… I’ve mostly tested with the stock antenna attached, and the android app. I’ve recently set up a physical linux rpi so that I don’t have to deal with the issues related to USB passthrough in hyper-v etc. It’s a debian based distro and getting Meshtastic setup was pretty easy with the existing docs. Now I can configure two radios with identical parameters using the CLI(bash script), and have one send out an incrementing message every 10 seconds (etc). Maybe I’ve underestimated how directional the ‘stock’ antennas on these boards are, but I put one in a second story window, and went into the backyard and couldn’t catch a packet…
I think I found your thread before posting. I definitely searched for that product on the US amazon site and found mixed reviews. I don’t know if I was looking at a different product though, amazon’s search algorithm is a bit fuzzy.
I guess it depends on what the other customers were actually using it for and if they bought it for the correct frequency. All i know is i tested it with my own NanoVNA and it seemed to be correctly tuned, unlike the stock antennas i got with my ttgo boards which seem to be tuned to 868MHz.
I found that the stock antennas weren’t actually that bad if you sorted out a ground plane for them as they were designed to have.
I read many specialized forums and see that many people do not have knowledge of antennas. At the same time, many shops on Ali take advantage of this. I am preparing a guide for making different antennas for our application. Unfortunately, I cannot post all the developments now, because materials require testing and measurements on the air. When ready, I will present several constructs to repeat.
For example, I did this today. 2-element collinear antenna for roof radio relay. In the next couple of days I will put it on the roof and with a friend we will go to measure the coverage with a signal from our village.
These are the ones I use: HW Series Antennas - Linx Technologies
Based on these findings: Testing & Reviewing LoRa® Antennas | by Mark Zachmann | Home Wireless | Medium
@RogerThat can you check to make sure that your antenna has the center pin on the connector? I recently had an antenna with horrible range until I realized I hadn’t installed the included adapter (the antenna was female SMA, as is the T-Beam, which meant I didn’t actually have an antenna connection).
Out of curiosity, has anyone tried any like these Laird phantom series for 915mhz? https://www.digikey.com/en/products/detail/laird-connectivity-inc/TRA9023P/2392252
I’ve tried larger outdoor 915mhz commercial fiberglass antennas (incidentally by a company that was bought by Laird), but never tried these really small form factor N-type.
Found another low-profile option from Linx (mentioned above and referenced in that LoRA antenna article):
A little 5.4dbi dipole sounds promising. Anyone tried these or something similar?
The Lynx ANT-916-MHW-SMA dipole came in from DigiKey today. VSWR looks pretty phenomenal. I’ll have to do some SNR A/B testing against stock stubbies.
Here are some antennas that I’ve tested.
From left to right
Ziisor Mag-mount antenna
Decent build quality for the price. Performance is as expected for a omni-directional antenna. The magnet isn’t very strong but it does the job. It needs to be mounted to a ground plane to work properly. VSWR is surprisingly good on multiple bands. That’s not necessarily a pro if you want out of band rejection. This was probably designed as a cellular antenna as it dips in all the right places for North American cell bands.
Maple Wireless Moxon Directional antenna
I really like this antenna. I haven’t verified the gain but real world performance indicates that it’s probably as advertised. It’s directional but the front lobe is pretty close to 180 degrees. Front to back ratio is impressive.
A mystery antenna
It was sold to me as a 915MHz LORA antenna from Amazon. The listing is no longer up so I can’t post it. Obviously it’s just a WIFI antenna and it sucks at 915MHz.
The stock TTGO T-Beam antenna
I’ve got two stock antennas that came with my T-Beams and both are pretty much equally sucky at 915MHz. The seem to be tuned for 770MHz. I opened one up to try to tune it but they are made with a tube instead of a wire so clipping a bit off the end isn’t really a possibility.
Forgive my ignorance, I’m looking to dip my toes into the directional antennas, and I’d need to get a IPEX-1 to SMA adapter, correct? Something like this?
…for this antenna listed above…
It really depends on the radios you have and the antenna you buy.
Yes. A year later but I have two of these. They are okay… not great by any means. They actually get outperformed in my particular scenario but a $13 knock off Jimmy rigged magnetic base antenna called “SuperBat 5db omni mag base” I got off Amazon for testing and tinkering purposes. (The antenna is horrible. Magnet and the “base” holding the connector and elements are simply sealed off by a magnetic sticker that is glued on. Pop that off and you have a circular magnet glued to a small 2 inch metal square with a whole in it. Inside that hole is a basic giant screw that holds some kind of copper braided wiring (def not rg58 or 174. Literally looks like your basic copper braid you find in basic power only usb 2 charging cords that only support 1.5A charging . And the worst part is it’s not even a “sleeve” that is attached to the ground plane by the screw, it’s literally half of the single braid just redirected. Then the other “half of the braid” is fed through a small hole into a plain cavity/recess that is supposed to be a copper housing but actually is mostly plastic. Then at the top of the recess is the bottom of a metal screw that acts to connect the antenna to the base (no even a coax threaded size screw. Just a random one with horrible quality metal. Peels off like lead)
Anyways after all that junk, that cheap SuperBat outperforms this linx t-dipole antenna by quite a bit.
Pretty disappointed because I saw the vsmr at 1.5. Also the antennas absolutely needs to be mounted sideways, not horizontally like most of the pictures show. If you do mount horizontally, you better not be trying to go further than 900m for your signal and the other receiving antenna needs to be horizontal as well without much change is elevation at all.
The “built-in” ground is obviously flawed on this. I tried both. I got the 180inch and 78 inch versions both. Both had similar results. The radiation pattern seems to go all over the place. Sometimes I’ll see a dive right in front of my by only 1km and then an hour later it disappears for a day or two and everything goes sideways instead. It’s not attached or even close to metal either.
Also the cable is rg174. Worse than even rg58. With 180 inches of cable, you are losing roughly 65-85% of your signal strength before it even hits the nodes of the antenna. With 78in you are loosing at about 50-65% loss. Way too long of a cable for rg174 and the tiny nodes on the antenna.
Essentially your 5.4db gets turned into 1-2db.
The antenna is a full half wave dipole which has by definition a gain of 2.15 dB above a isotropic antenna (which is imaginary because it can not exist in real world.)
2 meter of RG174 gives - 0.6 dB
So the gain is 1.55 dBi (2.15-0.6) so the claimed 5.4dBi is a fantasy which I would not expect from a product sold by Digikey
see: Isotropic Antenna - an overview | ScienceDirect Topics for the mathematical background