The BIG and SMALL ANTENNA topic part 2


(LoRaTracker) #191

The only (legal) purpose I can see for a gain antenna in a TTN setup is in overcoming connector and cable losses, but then its just easier and cheaper to increase the gateway TX power level to compensate.

Can I use a more powerfull antenna of 3 or 5 dbi?

Sure, but remember to reduce the transmit power in the Gateway setup to ensure you stay legal.

You soon realsie that adding a gain antenna and reducing the output power(to stay legal) puts you back to square one and you dont have extra distance.


(Pierrot10) #192

Hello
Thank for your reply.
What is the limit of the legal for Europe (France and Switzerland) There is knew recommandation.

I looked again on Digikey the Antenna. I found antenna with -2dbi and 2dbi. For wath are user the -2dbi antenna?
(As I am not realy sure about the gain reglementation, I will stay with 2dbi and not increase it)


(LoRaTracker) #193

Its assumed, in the UK at least, that the 14dBm power limit applies when using a +2.1dBi antenna.

Not sure if the limits apply to each and every possible European country, and neither do I have an intimate knowledge of the French and Swiss regulations …


(Ud Lo Ra) #194

put a link to one, but likely they are very small antennas to be soldered on the board of a node. Not always you need extreme gain and distance, size sometimes matter more.


(Pierrot10) #195

Hello!
Excpeted if I am wrong, in Switerland the powerlimit is 14dbi, as well. I then suppose, I can only use 2dbi antenna.

Here are the antenna I found and not sure about what to choose
2.1dbi: https://www.digikey.ch/product-detail/fr/linx-technologies-inc/ANT-868-PW-LP/ANT-868-PW-LP-ND/1962850
2dbi: https://www.digikey.ch/product-detail/fr/abracon-llc/AEACAC053010-S868/535-14819-ND/9962430
-2dbi : https://www.digikey.ch/product-detail/fr/linx-technologies-inc/ANT-868-PML-UFL/ANT-868-PML-UFL-ND/5592353
-2dbi : https://www.digikey.ch/product-detail/fr/linx-technologies-inc/ANT-868-PML/ANT-868-PML-ND/1769747

But I suppose, the -2dbi is not what I should buy.


(Ud Lo Ra) #196

Mmm… forget my comment, those are not SMD mounted antennas. And honestly it seems strange to me that they declare lower gain. Wait for a real expert in this matter :slight_smile:


(Arinze Izukanne) #197

I would suggest, before you increase antenna gain do the following.

  1. Reduce losses on both the nodes and the gateway antenna connections.
  2. Add a matching network on the nodes if you can.
    If those don’t work, then get better antennas. Often many antennas to not perform to their rating. However I have been able to achieve 5.9KM with this design from Texas Instruments. http://www.ti.com/lit/an/swra227e/swra227e.pdf

I can share gerber files of the antenna and matching network, then you can order PCB from your preferred vendor. All you need is solder on connectors and 1 SMD capacitor + 1 SMD Inductor and you are good to go.


(Pierrot10) #198

Hello, Thank a lot for your reply. Yes I am interrested about your gerber file. I am curious to see it and a such antenna will be very usefull for my next project.

I am not na expert abour antenna, but what do you mean by reducing losse.

The Texas Intrument antenna has apparently a db of 3-4dbi, that’s correct.

Last wueation what the real diffrérence with a such antenna https://shop.imst.de/wireless-modules/accessories/19/sma-antenna-for-ic880a-spi-wsa01-im880b-and-lite-gateway, excepted that your antenna can not be used outside. Then if I place into a plastic box, there is some recommandation about the material and the thickness to avoid doing an obstacle to the RF?

Great, thanks a lot


(Arinze Izukanne) #199

There is a loss at each connection point. Could be 0.5dB or more depending on the quality of the connectors. Reducing connectors, removing pigtails or reducing their lengths will help reduce these losses. Given the low power levels LoRa operates, such seemingly minor losses could be significant.

I will share a link to the Gerber later.


(Pierrot10) #200

Great! Thank a lot


(Arinze Izukanne) #201

Hi @pierrot10,

Click Here for the link to the antenna design files. You can download the gerber and BOM.

This SMA connector should fit the board …

And this male to male connector should allow you connect to existing nodes without a pigtail.

I usually integrate the antenna design on the same PCB with my node so the need for connectors and associated losses are eliminated.

Good luck


(Pierrot10) #202

Hello
Thanks a lot. May I ask you two question more.
Which material hoising do you use for your PCB (with include antenna). I guess it should a thin platic box?
Last question, what is L1. Can it be this? https://www.digikey.ch/product-detail/fr/ethertronics-avx/M620720/939-1066-2-ND/6072490
(I am not an expert with Antenna :slight_smile: )

Thank


(Arinze Izukanne) #203

Hi,

I have used a thin plastic box as well as cross section of a waste pipe. With the waste pipe, I had the node, antenna and battery encased. I have also used self amalgamating tape on one occasion.

The link you sent is for an antenna. L1 is an inductor, value is 1.8nH. Here is a link https://lcsc.com/product-detail/HF-Inductors_Guangdong-Fenghua-Advanced-Tech-VHF160808H1N8ST_C1026.html


(Pierrot10) #204

Hi,
Thank a lot for your reply and help!
Nice!


(Clumsy Pilot) #205

We are setting up several Lora stations on farms, to go with our agricultural sensors. What would you say is the best option for fixing to the side of a bar?

For the moment we ordered 12 dBi Taoglas Braccuda, and hope to range-test it next week.

Also I’ve done some casual testing (without ttn mapper) in city and got about 900 meter range
image


(LoRaTracker) #206

You are aware that to be legal you need to keep the ERP to 14dBm ?

If you use a standard gateway\node setup, which defaults to a TX power of 14dBm, that antenna would increase ERP to 24dBm…

In practice (with most TTN applications) the only legal use of a gain antenna is to offset connector and cable losses.


(Tim Everitt) #208

HI @ClumsyPilot, the following is the mechanical drawing of the Taoglas OMB.868.B12F21 antenna.

t12dBi-mount

I use a lot of the 5dBi equivalent of the 12dBi antenna that you have ordered. Per the mechanical drawings, I always fix them to standard 2inch/50mm telecom masts using the u-bolts that are delivered with the antenna.

You ask about attaching to the side of a “bar”. Do you mean “barn”? If so then don’t attach the antenna direct to the side of the barn, you need the entire antenna to stick up clear of the apex of the roof.

Are you aware that the 12dBi antenna is 2.4m long? You will need to use a substantial mast - like a scaffolding pole. The scaffolding pole is normally attached to the side of the building using standard heavy-duty telecom “T & K” brackets.

Following is a picture of LoRaWAN base-station using a Taoglas 5dBi (1m long) antenna mounted on a barn using T&K brackets, unistrut and a scaffolding pole. Your antenna is 2x the length of this antenna.

DSC_1931


(Jeff Uk) #209

Depending on your ant height & assuming you GW location is near Icentrum north of Aston Uni you are doing well to get signal west to where shown on the map beyond the Children’s hospital. Can I suggest you do a slow driving test n/ne along the A38 Aston Expressway towards/beyond the M6 intersection. You should be getting good coverage 300-400m all around you but then extending much further in the N/E quadrant. You should hold signal to the motorway, possibly loosing some from around Aston Park and across the River Tame valley picking up again as you close on the motorway intersection. Beyond the M6 if you continue and do some war driving around Gravely Hill area you should see coverage around there :slight_smile: you may also see signal along Victoria road between A38 & A34 and again west A34 towards Lozells on the B4144 or B4145. If you can demonstrate that then you know don’t have a setup range problem but rather a topography & building clutter problem :wink: No need for exotic ant in that area as this should be achievable with a typical As Supplied GW ant e.g. A 2dbi ‘rubber duck’. Should be ok for anything SF9-SF12. Only need greater sensitivity if trying to use lower SF’s for shorter on air time. Suggest you try same ‘drives’ (walks!?) with nodes @ different SF’s or repeat runs to compare and assess and with low duty cycle to avoid breaching regs…hence slow to get good geographic coverage without Tx gaps :wink:


#210

@Jeff-UK

this seems like a ‘job’ for you :wink:

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#211

x1325

x1326

x1327

yagi antenna GSM outdoor 9 units 13DBi 824-960mhz 900 mhz GSM CDMA (now € 10,66 incl. ! )

usable ? yes, perfect for a long range ‘field’ sensor node imho

x1330
I also tested these 11 DBi versions… they are very BAD