Help with antenna choice

#1

Hello,

I am looking to by omni-directional antenna for my Lora V3 which is due to arrive soon.
I live in EU. Which antenna should i pick up? 868 MHz or 915 MHz. Does it Matter?

Many thanks

#2

First is legal, the second is illegal to use in the EU, but you can own one if you want.

First will transmit signals in EU efficiently, the second will transmit EU frequency signals very inefficiently.

First speaks EU, the second is for use in USA or AU or many many other countries, but not EU.

Don’t forget to consider the dB gain on the antenna to remain within legal ERP and account for any line losses. Plus consider the fresnel zone in line of sight planning.

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#3

Thanks. I was just wondering if the lora devices transmit at certain frequency only or, at range… for example from 868 MHz to 915 MHz, or 868 MHz only, etc… :slight_smile: I am planning to get 5db antenna. It comes with 1 meter cable but i obviously wont be able to connect it straight to the heltec. So i was wondering should i use the 1 meter cable the antenna comes with, or should i just get a 10 cm cable from the heltec to the antenna and plug the 10cm cable into the antenna…?

https://www.aliexpress.com/item/1005005548920589.html?pdp_ext_f={"sku_id"%3A"12000033496469082"}&sourceType=1&spm=a2g0o.wish-manage-home.0.0

https://www.aliexpress.com/item/1005008538138113.html?pdp_ext_f={"sku_id"%3A"12000045620019831"}&sourceType=1&spm=a2g0o.wish-manage-home.0.0

So my question is, does this goes straight to the antenna, or to another 1 meter coax cable? :slight_smile:

#4

You REALLY need to learn about what is legal to transmit, at what frequencies and how often you can do so. And what the impact of the antenna gain will have on permitted power settings. Think speed limits on the roads, you can get away with it for a while but if you jam up someone else’s shared use of the ISM band, its very easy to pinpoint a location and then there’s paperwork, court appearances and fines to deal with.

As for the cables, each connection is a point of loss, so you need to minimise them. And then there is the whole range of types of connector as the links you provide demonstrate- the v3 has a uFl connector.

#5

Thanks, but i dont think any of these are likely to happen, it is all in the limits, 25mW, and 5db :slight_smile:

#6

Seems to be almost certain to happen with 5dB antenna at 25mW with one join on the connector and only 1m of cable, close to double permitted ERP.

But you do you.

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#7

May be i should rephrase this :). I wont exceed 25mw, with a 5db antenna :slight_smile: I guess that makes more sense :slight_smile:

#8

Power level isn’t the only rule - there’s also dutycycle. It’s forbidden to transmit too often, see the jamming part of @nmcc’s post. So you REALLY need to learn what is legal to transmit (and then include the part about being a nice neighbour which means not living on the edge of the law).

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#9

it sounds like it will be easier just to get a amateur radio license and transmit a little more :slight_smile:

#10

As your first question indicated some knowledge gaps regarding frequency plans in the EU, this statement seems a little disingenuous.

As does this - although it would help because you’d end up knowing about all this stuff. And you’d find out it makes no difference to ISM band use.

We are trying to provide some wisdom here and because it relates to legal issues, we try to play it straight. By all means do you, but it doesn’t inspire the continuation of any further assistance you may want.

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#11

My aim is to connect a device to my router and stream internet to my mobile phone across the town…

#12

If it were that simple and legal (which it is totally not, please refer to dutycycle and jamming the airwaves), it would have been done already by thousands of people…
But do you see any demonstrated working example of someone streaming WiFi over LoRa to use with their phone, that is actually a usable and legal solution?

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#13

WiFi on LoRa V3 connected to the router :white_check_mark:

TCP/IP over LoRa :x: Someone’s done it for microprocessor based systems but not so much for microcontrollers. The throughput would make a 1200/75 modem look positively speedy. And the latency would be awful.

LoRa receiver on your phone :heavy_minus_sign: you could wire up a LoRa radio to USB. Or you could use another LoRa V3 to receive the LoRa and act as an access point.

Line of sight :x: if the two antennas can’t see each other, it’s most likely to stop working.

The Why? What problem are you trying to solve. It may be that it is solvable but you’ve told us how you want to solve the thing, not the why.

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#14

In EU the legal frequency for LoRa is 868 MHz

#15

And 434MHz.

And there are some suggestions for channel plans for 434MHz for LoRaWAN.

But most of the gateways are in China …