Understanding Cable Loss and EIRP in Helium Hotspots - Mapping Network

Understanding Cable Loss and EIRP in Helium Hotspots

Helium hotspots are devices that allow wireless communication between different devices and networks. These hotspots rely on radio waves to transmit and receive data, and the strength of these radio waves is measured in terms of EIRP (Effective Isotropic Radiated Power). EIRP is the amount of power a radio transmitter can emit in a given direction, measured in decibels (dBm).

However, when radio waves travel through a cable, some of the power is lost due to the resistance of the cable. This is known as cable loss. Cable loss is measured in decibels (dB) and is subtracted from the EIRP to determine the actual power reaching the antenna. For example, if a radio transmitter has an EIRP of 20 dBm and the cable loss is 3 dB, the actual power reaching the antenna is 17 dBm. This can have a significant impact on the performance of on your hotspot.

To mitigate cable loss, it is important to use high-quality cables with low resistance. Additionally, the length of the cable should be kept as short as possible to minimize the amount of power lost. For example, if you are using a 50-foot cable, you may experience a loss of 3 dB. However, if you use a 25-foot cable, you would experience a loss of only 1.5 dB. 

LMR (Low Loss Microwave Radial) cables are a type of coaxial cable commonly used in wireless communications. LMR-200, LMR-400 and LMR-600 are three popular types of LMR cables. The number in the cable type refers to the approximate outer diameter of the cable in hundredths of an inch, so LMR-600 is larger in diameter than LMR-400 and so on. The larger the diameter of the cable, the lower the loss of signal over distance, resulting in better performance.

Another way to mitigate cable loss is to use outdoor enclosures to protect the cables and connections. Outdoor enclosures provide a waterproof and weather-resistant barrier that helps to keep the cables and connections in good condition, reducing the likelihood of damage and deterioration. They are designed to meet specific environmental and electrical requirements and are designed for outdoor use and provide protection against rain, sleet, snow, and damage from hose-directed water.

Another way to mitigate the effects of cable loss is to increase the EIRP. This can be done by using a directional antenna that focuses the radio waves in a specific direction. For example, using a high-gain antenna can increase the EIRP by 6 dB, effectively doubling the power reaching the antenna.

EIRP is a crucial factor in the performance of Helium hotspots. As EIRP increases, the range and throughput of the hotspot also increases. However, it is important to note that there are legal limits on the maximum EIRP that can be used, so it is important to stay within these limits to avoid causing interference with other devices. The Helium antenna transmission power must comply with local or regional limits. In Canada and United States this is currently a maximum EIRP of 36 dBm.

In summary, cable loss and EIRP are important factors to consider when setting up and maintaining Helium hotspots. By understanding these concepts, and taking steps to mitigate cable loss and increase EIRP, such as using high-quality cables, shorter cable length, and outdoor enclosures, you can improve the performance of your hotspot and ensure reliable wireless communication.

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