In LoRa applications or using Helium hotspots, the following situation often occurs: Helium hotspots cannot receive other hotspot information, or data sent through terminal nodes cannot be transmitted to the LoRaWAN server, resulting in very low coverage of Helium hotspots. Therefore, we need to use an external antenna to change this situation!
Why do I need an external/outdoor antenna?
This is not difficult to understand with the help of an external antenna, because Helium hotspots mainly rely on interaction with other hotspots to achieve coverage. As we know Helium hotspots include radio communication systems, like mobile phones or two-way radios. Therefore, only the signal is strong enough to receive more data. Simply put, it needs to receive the RF of other Helium hotspots in order to increase the coverage of the hotspots. Therefore, the key point to improve the coverage of Helium hotspot is to enhance the signal. At this time, we need to use an LoRa antenna outdoor.
However, the use of an external antenna does not mean that we can install an antenna, but we have to choose a "good antenna" based on the real-time situation and make reasonable use of it to better receive signals and expand the range of hot spots.
How can a good antenna help Helium expand its coverage?
1. High-gain antenna makes energy more concentrated
Take RAK's glass fiber reinforced plastic antenna as an example. The default antenna for Helium hotspot is omnidirectional antenna. The emission of these antennas on the plane is equal to the radio. These are basically omnidirectional dipoles, whose radiation direction is equal to the vertical axis. Each antenna has a gain number associated with it. Compared with isotropic antennas, the antenna gain measured in dBi refers to the degree to which the antenna can concentrate energy in a specific direction.
The additional antenna of the RAK Helium hotspot is 2.8 dBi in the EU and 2.3 dBi in the United States, while the gains of the RAK glass antenna are 5.8 dBi and 8dbi respectively (note: CN470 currently only has 5.8dbi).
Therefore, if the frequency range is 900-930 MHz, the peak gain is 8 dBi. This means that compared with the attached antenna, it will amplify the signal by more than 4 times and can reach a greater distance.
You may ask: Why not just choose the antenna with the highest gain? The answer is simple, that is, increasing the antenna gain comes at a price. The higher the gain of the antenna, the more concentrated its energy. Looking at the picture below, we can see how the antennas with different gains emit energy.
Therefore, if you just blindly increase the antenna gain, as the antenna energy becomes more concentrated, you may not be able to communicate with other hot spots that fall outside the beam.
At this time, the antenna itself must be considered in conjunction with other factors.
2. According to the location, choose the right antenna
To choose the antenna that suits your needs, one of the key factors is location. The main thing is where you are and where you want to receive other hotspots. If your hotspot is located on the top of a very far building, it is better to choose an 8 dBi booster antenna. However, if your nearby hotspots are relatively close, considering the 300-meter rule (the minimum distance between hotspots), it makes more sense to choose an antenna with a 5.8 dBi gain. So, the only way to understand what is best for you is to experiment. Try different antennas to see which antenna is best for your environment.
In addition, considering the antenna efficiency, you must pay attention to whether the location is shielded when you choose to deploy the antenna. Then, choose the antenna with higher antenna efficiency. Generally, the antenna can only radiate about half of the power provided to it. The efficiency of the RAK antenna is about 50%, which can be said to basically reach the top level.
In addition, it is recommended that the antenna installation be placed at the highest point that can be safely reached, such as the roof. However, it is more difficult to install and deploy antennas on the roof, and manual installation costs are more expensive. Therefore, it is very important to perfect the antenna of the accessory. For example: RAK's antenna has a very convenient magnetic base, which can be easily installed on the commanding height of the house and close to the window.
3. Complete antenna accessories make deployment more reasonable and faster
As mentioned above, the deployment of Helium needs to be in various locations, and deployment and installation are also a big difficulty. Dangerous locations, rainy weather, and thunderstorms often make the deployment "dead-term", so be sure to choose an antenna with perfect protection and accessories.
RAK provides a series of matching accessories while providing antennas. Like the RAK fiberglass antenna, it is composed of glass fiber, which is very sturdy and not affected by the outside world (protection level is IP67). This is one of the most important aspects of the antenna-it can be used outdoors and can be installed at the viewing height of other Helium hotspots. In addition, this in turn eliminates a large amount of attenuation due to obstacles in the signal path, resulting in lower path loss and greater coverage.
In addition, RAK's indoor environment antennas will be matched with: indoor deployment antenna magnetic base, antenna low-loss extension cable, antenna glass sticker, etc.
Outdoor environment antennas will be matched with: outdoor enclosure kit, antenna lightning arrester, antenna pole kit, etc.
Three, summary
In general, if you want to enhance the deployment of Helium, it is recommended that you try different frequency antennas, such as RAKwireless 5.8 dBi and 8 dBi antennas to maximize your coverage; also, place the antenna at a high point In order to maximize the communication with node devices or other Helium hotspots; in addition, it is also very important to improve the antenna accessories, which can make the installation and deployment of the antenna more convenient.
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