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
||Paradar 868Mhz LoraWAN antenna, weatherproof with N-female…||£109.99||Buy on Amazon|
||Paradar 868Mhz LoraWAN antenna, weatherproof with N-female…||£59.99||Buy on Amazon|
||868MHZ 12DBI OMNI ANTENNA WITH N||£568.83||Buy on Amazon|
Be warned, the Taoglas 12dbi option is not likely the best choice unless there are not many hotspots near you.
- Glass Fiber LoRa Antenna Peak Gain (5.8dbi) by Nebra for £40 – shipped when the hotspots ship
- Glass Fiber LoRa Antenna (3dBm) by Nebra for £35.99 – shipped when the hotspots ship
- Various antenna options on CalChip (just make sure it is a 868Mhz antenna)
Helium Hotspot Antennas for the US 915Mhz models of the Helium Hotspot
- LoRa Gateway Antenna 3dbi Gain Antenna – On Amazon with stock available on the 18th for $39.99
- 5.8dbi RAK Fiber Glass Antenna Kit for Helium Hotspot – $40
- Various antenna options on CalChip (just make sure it is a 915Mhz antenna)
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
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)
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.
||TRENDnet (6m) Low Loss RP-SMA Male to RP-SMA Female Antenna…||£23.00||Buy on Amazon|
||Ultra Low Loss Coax Cable 10ft, Ancable N Male to RP-SMA…||£11.99||Buy on Amazon|
Posted by Mighty Gadget Blog: UK Technology News and Reviews