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I am searching a antenna for LoRa module. my first priority is distance. which is more long range, it is better for me. There are 3, 433Mhz 3dBi antennas. Can you help me which is best and why? if you give a basic information about smith chart and swr chart, I will be appreciated to you.

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I will use this LoRa module

First one Link charts

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Second one Link

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Last one Link

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    \$\begingroup\$ your question makes no sense: Antennas don't have a range, and your antenna smith chart tells us nothing about your system – neither impedance of your device (which quite likely isn't very close to what you need, anyway, so you'll need matching anyways, so the smith chart really doesn't matter much, if at all, just tells you what kind of matching circuit you'll need), nor about the actually important factors (directivity and your geometric setup). So, all in all, you're asking us "how to test an antenna for an unspecified use case", and that's, I'm afraid, really too broad. \$\endgroup\$
    – Marcus Müller
    May 13, 2021 at 23:45
  • \$\begingroup\$ (Full disclosure: I've voted to close this as "needs focus", because the Smith chart doesn't tell us which antenna is "better", and "reach" is a system, not an antenna property, which means you're lacking too many basics to be explained in a compact answer.) \$\endgroup\$
    – Marcus Müller
    May 13, 2021 at 23:48
  • \$\begingroup\$ @MarcusMüller well you are right I've very weak knowledge about antennas. While I was buying antenna, I ve seen those 3 antenna and I didnt match which is best for me. I will use this lora module ebyte.com/en/product-view-news.aspx?id=108 . \$\endgroup\$
    – mehmet
    May 13, 2021 at 23:58
  • \$\begingroup\$ Which country are you intending to use those in? The only region where LoRa 433 is normalised is the EU region, and the limit there is 12.15 dBm EIRP (that means including antenna gain). Other regions will likely have different limits, if they allow use of the 433 MHz band at all for LoRa. \$\endgroup\$
    – jcaron
    May 15, 2021 at 14:50
  • \$\begingroup\$ Also note that the label on the picture show an FCC ID which is only valid for the 915 MHz band. Unless the real device has a different FCC ID for operation in the 433 MHz band, it is illegal to operate in the US. It’s probably not approved in many/most other countries either. \$\endgroup\$
    – jcaron
    May 15, 2021 at 14:58

2 Answers 2

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A dummy load has a perfect match across a wide spectrum. That doesn't make them a good antenna.

What you want are radiation patterns and antenna efficiency. As a rule of thumb; the smaller you try and make an antenna for a given wavelength, the lower the efficiency of the antenna.

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  • \$\begingroup\$ I was just about to make that comment. \$\endgroup\$
    – rfdave
    May 14, 2021 at 1:06
  • \$\begingroup\$ so what do you think of this LoRa module, if you were in my place, which antenna would you choose? \$\endgroup\$
    – mehmet
    May 14, 2021 at 1:54
  • \$\begingroup\$ If I were in your place, I'd have way more information that has been asked for in the comments already, based on which I could actually make a decision. As said in the other comments, from your Smith charts alone, no decision can be made, and you will have to acquire more expertise yourself. \$\endgroup\$
    – mmmm
    May 14, 2021 at 8:21
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Well after watching some videos and reading I think first one is better (intheory) because it is closest to 50 ohm (smith chart) and lowest swr

Viode links:

https://www.youtube.com/watch?v=_pjcEKQY_Tk

https://www.youtube.com/watch?v=6cVYsHCLKq8

https://www.youtube.com/watch?v=J3PBL9oLPX8

docs:

https://www.ebyte.com/en/new-view-info.html?id=304

https://www.coredump.ch/2017/04/30/lorawan-868mhz-antenna-test-part-2/

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