Helium Hotspot Antenna Upgrade Guide – 8dbi vs 5.8dbi vs 3dbi – Which cables & connectors to choose to reduce signal loss?

I have previously written a post on upgrading my Helium Hotspot with the MikroTik LoRa 6.5dBi Omni Antenna.

Since then, I have made a lot of changes, obsessing about finding the best performance. Sadly my performance has dropped due to a large number of hotspots in my town. I wish I had used the optimal set up from the start.

It turns out antennas are more complex than you think. It is not just a case of buying the most powerful one you can find and placing it as high as possible.

8dbi vs 5.8dbi vs 3dbi Antenna – Different antenna gains have different degrees of coverage

Omnidirectional antennas are not quite as omnidirectional as you think when you increase the antenna gain. So you can’t just buy a Taoglas Barracuda 12dBi antenna and think it will cover a huge distance with 360-degree coverage – trust me, I tried, and it is a super expensive antenna.

The lower the gain, the better the coverage, at 2dbi, you get 360° coverage, but at 5dbi, it drops down to 40° then 7dbi is 30°.

So in a city with a lot of hotspots around, you might be best off with a lower gain antenna.

Then, of course, is the placement; higher with fewer obstructions is better, obviously. In hindsight, I wish I had paid to get an aerial company to come around and fit my antenna on my chimney.

Also, remember, you will need an antenna that is compatible with your specific region. Some antennas cover multiple frequencies, which is fine, as long as it covers your frequency.

  • For the UK this is 868Mhz
  • For the US this is 915Mhz

Helium Hotspot Antennas for the UK 868Mhz models of the Helium Hotspot

Be warned, the Taoglas 12dbi option is not likely the best choice unless there are not many hotspots near you.

Helium Hotspot Antennas for the US 915Mhz models of the Helium Hotspot

Signal loss through the cable

You also need to consider how the signal degrades on the way back from the antenna to your hotspot. The longer the cable, the bigger the signal loss. Again, in hindsight, I messed up here, buying cheap cables on Amazon.  Similarly, if you use the SMA adaptors you buy on Amazon, you can potentially introduce further signal loss.

You can get low loss cable, Amazon has lots of these listings, but a decent low loss cable is LMR-400 which is harder to find and much more expensive.

Just be warned, the LMR-400 is very thick, I had an old hole coming through into my office for a TV antenna, and I only just managed to squeeze it through. I had previously run cables through a small window, leaving a small gap with the window partially closed, but this cable would have left a huge gap.

Custom cable and which connectors to use on your antenna  

Antenna with N-Type connector going to RP SMA MALE

You can get cable made up to custom lengths, this will be your ideal option allowing you to select the minimum length required to reach your hotspot.

To avoid using adaptors, you will need to work out which cable end you need. For the MikroTik LoRa 6.5dBi Omni Antenna I use, it has an SMA female end while the Helium Hotspot has an RP-SMA Female .

So for the MikroTik, I needed the opposite connectors, which are RP SMA MALE (Helium hotspot side) to an SMA Male (Antenna side)

I ended up buying off  McGill Microwave Systems on eBay. I think it was this cable but then I messaged them asking for the RP SMA MALE & SMA Male cable ends.

Some antennas use the larger N-Type Male connection, this includes the RAK 5.8dbi Fiber Glass Antenna Kit, so this would require a N-type female 

If you get a cable made up I would suggest confirming with the company the exact ends required, I get easily confused with all the connector types and it is easy to get mixed up. A professional will know best.

Some of the options on Amazon are available below, but you may need to buy the adaptors to fit things properly.

Posted by Mighty Gadget Blog: UK Technology News and Reviews

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