Hc-12 module - do I need external antenna?

Projects Networking, Protocols, and Devices
1

Hello guys! I've just oredered x2 HC-12 modules - for long-distance communication between 2 arduinos. They aren't delivered, but I have some concerns. In its package, every HC-12 module has one small spring antenna. I read a few topics and it seems like its not very suitable for bigger distances (aka >200m). The module has one small port for wiring external antenna. My questions:

  1. Am I wrong that the spring antenna is irrelevant?
  2. Would using bigger antenna improve my range?
  3. If q. 2 == true, then may you please suggest me a suitable antenna? Requirements: x2 of those must have range of atleast 500m (perfects conditions, the module will be max power of course), also they both must be somewhat cheap - $5 each ot MAX. $7 each.

Thank you!

P.S. I could not provide images or links to datasheets or shops because of reasons :D, so please check it yourself. Thanks in advance.

2

Under 'perfect' conditions then even the HC12s should go far enough on the spring antennas.

And as a general point it makes no sense to define a price limit for the radios, a cheap radio might need an expensive antenna to make it work.

Also be aware that the max power of the HC-12 might be illegal to use, and adding bigger antennas might be illegal as well.

3

Dont worry about the legal status, in my country there isn't such problem. About the antenna - alright, I'll give an example. Lets say you live on 10th floor. Thats about 30-35m height. Can I place the first HC-12 at the 1th floor and the second one at home and expect them to communicate? Note that there are many walls between them (atleast 10) and numerous routers and similar things. If I put bigger antenna - like 20cm one and set the Hc-12's powers to 100mW, will they communicate?
And again pls suggest an antenna (if it will help).

4

JMD1:
Dont worry about the legal status, in my country there isn't such problem.

Really, thats a surprise.

5

Alright is someone gonna suggest me an antenna? From ebay/amazon/aliexpress/dx/gearbest?
Up to $5 per piece? Thanks.

6

is there a particular reason you chose the HC-12 module over an NRF24L01? Those can come with long range antennae and are about $2 USD each on aliExpress. I haven't personally tested the long range antennae, but they're advertised as working up to 1100 meters.

These are the long range versions:

7

I didn't know about the NRF24LO1. Thanks for the suggestion.
Anyway, I've already oredered the HC-12 modules and paid them.
And again. Do I need long range antenna or I can rely on the spring one?

8

The spring antennas are normal mode helicals and they work OK provided there is no metal near them , ie within
3 - 4 inches as nearby metal detunes them.
They are primarily for projects in plastic boxes so how well they will work depends on their proximity to anything else.