All You Need to Know about External Helium Antennas for Maximum Range

To get the most out of your Helium Miner you will need an external antenna mounted high up. But there are so many different version types and decibel versions around.

In this post, we will explain what works for a specific environment and how you can benefit from increased HNT/ IOT rewards.

There are 3 different frequencies around the world for Helium Miners so it is important that your antenna matches your country.

• 470 MHz (CN470) – this frequency is suitable for China.
• 868 MHz (EU868, IN865, RU864) – this frequency is suitable for the EU, India, Russia, and a variety of other countries.
• 915 MHz (US915, AU915, KR920, AS923-1/2/3) – this frequency is suitable for the USA, Australia, New Zealand, and other countries in South America and Asia.

You must match your antenna to the frequency of your helium miner otherwise it won’t work.

Why use an external LoRa antenna?

The stock antenna that comes with helium miners such as my Sensecap is designed for indoor use only. The range depends on the environment:

• Rural areas: expect 10 miles or more.
• Dense areas: between 1-3 miles.

But if we replace the stock helium miner antenna with an external antenna you can greatly increase the range of the radio waves often by a factor of 10x. But you have to get the antenna mounted high and use low-loss cables.

The majority of external antennas are called omnidirectional. This means the radio signal is transmitted out like a donut shape. Depending on the dBi decibel rating or gain you may get different shapes.

The apparent increase in signal or gain is not an amplification of the signal, but it is the result of the redistribution of available Radio Frequency (RF) signal into a preferred direction. Therefore the increase in a signal using an external antenna is called gain and is measured in dBi. These units are referred to as decibels-isotropic (dBi)

Many people think that a higher gain antenna will give them the strongest signal. This is somewhat incorrect as an increase in gain will result in a smaller beam angle.

External 3dBi LoRa antenna 915MHz

This external 3dBi antenna for helium miners is the closest to most helium miners’ stock antenna. But don’t be fooled into thinking they are the same. Due to its larger size and being mounted outdoors, you will get increased range and you will be able to detect many more hotspots in your area.

The upside is increased witnesses and increased earnings. This external 3dBi antenna shown above is 40cm long which is a good length for transmitting and receiving far away signals.

There are some things to consider with a 3dBi antenna. Due to its lower gain, you will get a shorter range but increased local area coverage, especially in the middle of a large city.

3dBi external antennas are excellent for high-density city environments when mounted up high. They will cover a much larger area compared to say an 8dBi antenna that may skip over the top of lower-mounted hotspots.

External 5.8 dBi antenna

An external 5.8dBi antenna is a great compromise between distance and coverage. It sits in between 3dBi and 8dBi and is my antenna of choice in suburban areas. Like all antennas, it must be mounted as high as you can get it. The reason for this is due to RF waves when they hit a solid object they lose energy.

An external 5.8 dBi antenna has a beam pattern of around 35 deg. This is the spread of radiofrequency waves out from the center of the antenna.

This is why if you are very high up in a skyscraper the RF waves may not detect low-down hotspots close to your antenna.

You want to first scan the area with a 3 dBi antenna to see if there are close hotspots to you within 1 mile. Then change over the antenna to a 5.8 dBi to see if you can connect to other HNT miners further out.

I find that most of my antennas are mounted between 10m to 15m and I can connect to hotspots as close as 500m and as far out as 20 miles in open areas with 5dBi.

Each circumstance is different so it is best to test out a few different antennas.

External 8dBi antenna

Now these external 8dBi antennas are the heavy hitters in the helium mining network. They are designed to send a signal far out into the countryside that doesn’t have my interference with buildings, mountains, or trees. As we mentioned earlier many people think that a higher gain antenna will give them the strongest signal so they buy an 8dBi or 10dBi antenna and wonder why they can’t connect to nearby hotspots.

The diagram below shows the side views of omnidirectional antennas which will explain beam patterns. (Not to scale)

Now the 8dBi antenna has a very narrow beam at around 27 deg depending on the brand and model. Excellent for hard-to-reach far away hotspots, but not so good for ones that are close.

If you are new to helium mining or would like to know more we have done a post on all you need to know how to set up a helium miner.

Is a higher dB antenna better?

A lower gain antenna is great to cover hotspots in a close dense city area, whereas a higher gain antenna is great for flat country areas with fewer buildings. Think of it as a low gain antenna is a bright torch that lights up a room but not much further. A high gain antenna like 9dBi and above is more like a laser beam that can travel many Km.

So a high-gain antenna is better if you need to connect to a hotspot many miles away in flat rural areas.

Are all Helium miner antennas Omnidirectional?

Over 95% of all helium miners are omnidirectional. This is because they are the most versatile and easy to install. There are a few specialized direction antennas called sectors or directional antennas that transmit and receive the signal RF waves towards the front. These require more specialized knowledge to direct the antenna to the source signal.

Directional antennas are best used on the side of a mountain where there is no use sending out a signal behind you as it would be blocked anyway.

What type of connection is on the bottom of Lora Antennas?

Most of the time the connection for LoRawan external helium miner antennas is N-Type male. There are pre-made LMR400 cables with an N-type Male and an RP-SMA Male on the other end for the helium miners. This way it is just a plug-and-play job. Work out the cable run length and order a cable made to suit the correct connections.

For every adaptor you add to the circuit, you add resistance that will cause a loss in the signal. Buy the right cable so you don’t need to use male-to-female adaptors. Make sure to use quality high-shielding cables for your external antenna.

Does a Helium antenna need a lightning arrestor?

Yes if you are installing your helium antenna outside on your roof or on a long pole you will need to ground the Helium antenna via an N-Type lightning arrestor. You can do this with some 10 AWG earthing cables and an earth stake. This is because of built-up static electricity during storms. The lightning arrestor will have an earth screw to which you can attach the earth cable.

If you do receive a lighting strike the lightning arrestor will fail and open circuit the antenna cable. This should protect your equipment from extremely high voltages caused by the lightning strike. You will need to replace the lightning arrestor after the internal fuse open circuits. They are easy to test with the use of a multimeter.

Lmr400 vs Rg6 antenna cable

To get the best result, low signal loss, and better noise reduction you should use LMR400 coaxial cable rather than the lower grade RG6 cable which is used for TV antennas.

There is a slight increase in cost for LMR400 vs Rg6 cables. LMR600 cable is recommended for cable runs up to 20m. Here is a great Coaxial Cable Attenuation & Power Handling Calculator. Just select the cable type, distance, and frequency of the antenna to work out the cable loss and other performance parameters.

For example, an LMR400 cable with a 30-foot length with a 915MHz frequency will have the following properties.

Product Performance Parameters

Nominal Attenuation	4.6 dB/100 ft, 15.2 dB/100 m
Average Power	0.5 kW
Cable Vg	85.0%
Nominal Td	1.2 ns/ft, 3.9 ns/m
Capacitance	23.9 pF/ft, 78.4 pF/m
Typical Connector Loss	0.1 dB/pair

LMR400 Cable Performance for 300 foot run.

Maximum Cable Assembly Insertion Loss	1.6 dB
Cable Run Efficiency	72.6%
Cable Run Time Delay	35.9 ns

Best Antennas for Helium Hotspots

Each antenna is designed for a specific use case, height, and topology. You will need to know the following questions.

• Are you in a tall building? Eg Skyscrapers go for a 3dBi antenna.
• Are you in the city? 3dBi antenna may be best
• Are you in the suburbs? 3dBi and 5.8dBi may be best.
• Are you living in wide open spaces? Eg farm. 5.8 to 8 dBi should work well.
• Single story house? With a high antenna go for 3 to 5.8dBi antenna.
• Double story house Installation? Go for a 3dBi to 5.8dBi antenna.

Check out the video below on the best antenna for your helium hotspot it is explained well.

Are Ebay external Helium miner antennas any good?

There are some good ones and some bad ones. The way to spot a bad LoRa antenna is if there are not any technical specifications. You are looking for information like this which is for a good 5.8 dBi Lora antenna.

Specifications

• Full-wave antenna
• 80 cm long
• Covers AU915, US915, & AS923 MHz LoRa bands
• Antenna Gain: 5.8 dBi
• Standard 50-ohm impedance
• While perfectly fine for low power use, it can operate up to 10 watts
• Durable Fibreglass sheath (not plastic)
• Polarization: Linear
• Connector Type: N-Male
• Operation Temperature: -40 to 80 degrees

If the specifications are missing it often is a cheap non-tuned antenna.

You also want to have a look at the beam pattern and if they are approved for use in your area. Make sure the parts are glued together so that the rain will not get into the internals. I have seen cheap helium antennas fly apart in strong winds due to a lack of glued fittings.

What helium miners are good?

There are many helium miners that perform well such as Nebra, Sincrobit, Sensecap, Bobcats, and Linxdot. One thing to check is that they have stock and fast shipping, many don’t at the moment.

My pick is Sensecap as they have regular updates and fast shipping.

When buying a helium miner check that you can upgrade the antenna and that you are buying a miner that works in your area, such as AU Australia, US America, or EU Europe.

Conclusion

There is not one antenna that will fit every area. You need to work out how high your antenna will be, how many obstacles are in the way, and the topography.

The Helium IoT network is the fastest-growing wireless network in the world am I am glad to be part of the process. The great thing is I get to learn so much from many smart people around the world on how antennas work.

The cost to upgrade to an external helium miner antenna is small. You will see increased gains and extra range compared to an indoor antenna. This is a long-term commitment do it right the first time and you will be rewarded over the life of the project.

Remember to get your antenna outside as high as you can and suit the antenna to the area. Happy IOT mining people.