# Panel or Yagi Directional Antennas for Helium

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## Helium Antennas

Helium miners ship with Omnidirectional Monopole Antennas. These are the same type of antennas that are used on Walkie-talkies and Wi-Fi access points. Omnidirectional antennas radiate and receive energy from all directions. They work well in most situations where you have an equal distribution of Helium hotspots all around you. Antennas that ship with Helium miners usually have low gain – typically 2 dBi or 3 dBi.

Many Helium miners have upgraded their antennas with higher gain omnidirectional antennas such as the one below. These antennas focus the energy relative to a lower gain equivalent. They have a narrower beam and are able to get larger range at the expense of broader coverage.

Antenna gain is measured in dBi (dB gain relative to an isotropic radiator) and a function of antenna factor and frequency of operation.

Depending on your environment, a higher gain antenna can result in more witnesses and therefore higher HNT earnings.

This picture by RAKwireless shows how the antenna beam narrows with increasing antenna gain.

If you live on the top floor of a tall apartment building and use a high gain antenna, it may not witness beacons from hotspots in the same or neighboring buildings on lower floors. Instead it will witness beacons from far away. That’s the trade-off between low and high gain antennas.

Use this calculator to understand how the gain of an antenna influences the range of the communication system. The calculator uses the Free space path loss equations and represents ideal propagation conditions. Results from it are very optimistic. However, it can be used to see the impact of antenna gain, cable loss, sensitivity and transmit power.

In the case of Helium the only parameters within user control are antenna gain and height. In an ideal operating environment, an unobstructed propagation path between transmitter and receiver is assumed.

## Directional Antennas

What if you want to focus the energy into any one particular direction? In this case you would need to use a directional antenna.

The above picture shows the radiation pattern of a directional antenna. You can see that there’s more energy in the front relative to the back lobe.

Let’s take a look at two situations where you might want to consider this type of antenna:

### Hotspots around you are not uniformly distributed

In the following picture you can see the absence of Helium miners to the left in the water and a high concentration of miners to the right of the miner in focus. As a result it doesn’t make sense to send any beacons and you won’t be receiving any beacons from the ocean area.

In this case it makes sense to make a tradeoff – i.e. for an antenna to instead focus its energy to the right.

### Hotspots in one direction have better transmit scale than other directions

In this picture you can see the regions with the red Hex’s in the upper right quadrant of the picture relative to the lower left quadrant where there’s more green. Green indicates transmit scales closer to one.

In general it’s preferred to receive beacons from the green area or higher transmit scales as the HNT rewards are higher.

## Directional Antennas for Helium

In both of the situations above it makes sense to experiment with directional antennas to improve witness rewards. Let’s take a look at two popular options for directional antennas:

• Panel Antenna
• Yagi Antenna

## Where are Panel Antennas Used?

If you live in a city, you’re likely surrounded by panel antennas. These are used by cell phone companies. They are also called sector antennas. Panels direct their energy in a specific direction.

Radio frequency (RF) energy is not transmitted down to the ground nor is it transmitted behind the antenna. The RF energy emitted by the antenna is strongest within the directional beam, directly in front and close to the antenna. The energy level decreases exponentially with increasing distance away from the antenna.

Panel antennas like all other antennas are designed to operate in specific frequency bands. The one above operates in 915 MHz which is suitable for North America and other regions of the world such as Australia. The panel antenna shown below operates at 868 MHz which is suitable for European Helium Miners.

## Where are Yagi Antennas Used?

Yagi or Yagi-Uda antennas are used for TV reception, cell phone boosters and other applications.

In both of these situations, you generally know in what general direction the TV transmitter or cellular base station is located. The antenna can then be pointed in that direction to facilitate focused signal reception. The Yagi antenna pictured above provides broad band coverage. It operates across the frequency range of 700-2700 MHz so it covers both of the major Helium bands – US915 and EU868.

## Yagi vs Panel comparison

Let’s take a look at some of the differences between the two directional antennas:

### Beamwidth and coverage

Panel antennas have a wider beam, which results in greater coverage relative to a Yagi Antenna when the signal sources are spread over a larger area. A Yagi Antenna on the other hand, is able to provide much higher gain relative to a Panel Antenna.

### Size and Weight

As well, a high gain panel antenna can be quite large and heavy. A high gain Yagi can be long, but otherwise is very light by comparison. Many RF interference hunting professionals use handheld Yagi antennas to exactly pinpoint the source of interference.

### Cost

There is no major difference in cost when it comes to panel relative to Yagi. That being said, panel antennas from reputable manufacturers like McGill Microwave do tend to be on the pricier side of things.

## Yagi or Panel which one should I pick?

If you are budget constrained and have to pick one over the other, we recommend picking the panel antenna. Note that panel antennas are tuned to operate in a specific frequency band so you can’t use a US915 in Europe or an EU868 Panel antenna in USA. These antennas provide a good balance between directional attributes and gain relative to an omni-directional antenna.

Also panel antennas are not as focused as Yagi antennas and that can be a positive or a negative depending on your situation.

If you are not budget constrained and can afford an experiment or two, we suggest getting both and trying them out. When running an experiment with antennas, it’s also recommended to try each one out for a week at least to see the effect on HNT earnings. You also may want to study the RSSI and SNR readings from specific beacons.

RSSI stands for Received Signal Strength Indicator and is a measure of received signal power or energy. The concept is similar for any wireless device and in this post we have explained it within the context of a Ring doorbell.

SNR stands for Signal-to-Noise Ratio. Here is a post that explains SNR in detail and how to measure it in the lab.

## Summary

In this post we have reviewed directional antennas and how they might be beneficial for certain Helium deployments. We provided two specific scenarios. If you are interested in experimenting with a directional antenna to see the effect on earnings, we recommend the following antennas: