Hopefully by this stage in the guide you have an idea about your potential good locations and it’s time to look at what sort of antenna setup might perform best for you. Because everybody has a different scenario, well look at 3 different range dBi antennas and what scenarios could be best suited for each.

Sections

• dBi
• Cable
• 0 – 3.8dBi Antennas
• 4 – 5.8dBi Antennas
• 6 – 10dBi Antennas
• PoCv11 Update

CABLE & EXTERNAL ANTENNAS

Before we get stuck into all the dBi’s, what is a dBi? Well it stands for decibel relative to isotrope, and is a ratio. Antennas manufacturers use dBi to measure an antennas gain perforance. In other words this is the amount of power the antenna has to send or receive from a specific direction. It’s important to note that all the antennas you plug in have the same power available to use, the dBi value displays the changes in how or where that power is transmitted and received.

The power the device has available (dB) plus your antennas gain (dBi) combined is your ERP which is governed by local regulations. So we don’t have bags of power and legally we aren’t allowed to amp it up. So we have to preserve and protect what power we do have. Additionally, after the POC 11 update your hotspot should already be configured to keep you within local guidelines providing you give Helium your correct information.

Cable

Whats the highest point on your proposed property? Can you attach an antenna here? If so, how far away is it to the nearest indoor power supply? The length of the cable is of upmost importance. With all cable, in all cases, it takes a little bit, or sometimes a lot of power to pass from a device through the connections, then the wire, then the connections, and finally into your device. So its really important that we use a low loss type of coaxial cable in particular one of a 50ohms specification.

Some commonly used cables include RG8, LMR400 and LMR600. Your decision here is based upon your preferred spend, your actual supply availabilty and your super accurate algebra calculations! You can skip the last step, any of these is fine! However, you may want to do algebra and that would be fine, this guide is all about maximising.

0 – 3.8 dBi Antennas

So starting, firstly at the lower end of the scale from 0dBi to 4 dBi, these are generally speaking the stock antennas that are supplied with your hotspot but not always, as we’ll see. In many cases, these antennas are the best antenna you can have connected. However the problem with many, is they are attached directly to the hotspot, which isn’t waterproof. Since we need an antenna outdoors this presents us with a challenge. We would need some cable.

But its not as simple as using the same antenna outside. For starters, external antennas, in general, come with an N type fitting, which is much larger and more robust. It also matches the thickness of the new cable which is a vast upgrade. Whilst yes you could use converters, others prefer not to due to potential loss, plus some are planning to upgrade their antennas.

These antennas are good for busy areas, and places with no or little horizon visibility. For the lowest dBi you have signal coverage that would resemble a sphere. So all the hotpsots power is being sent in every direction possible. This option is sure to provide the best coverage around your location and Helium recommends this range of antennas are used, to maximise their coverage area.

PoCv11 update is an important update that should be considered carefully.

4 – 5.8dBi

For many this middle ground is a sweet spot, a catch all. The very popular Bobcat Hotspot comes with a 4dBi antenna connected to 60cm of cable. For the average place this is going to offer you the best performance. Get it as high as possible.

6 – 10dBi+

The big boys! With the least coverage area in your immediate vicinity, and historically used for point to point communications across well placed high structures or communications towers. This sort of setup has shown to be effective with high locations and lone wolf type scenarios, again, with good visibility. After the PoCv11 update without proper configuration this size of antenna may cause some people issues.

PoCv11

“One of the key parts of the PoCv11 update is that your transmission power will be scaled down to fit local (regional or national) regulations.

Prior to PoCv11, a gain of 1.2 dBi was assumed when validating every receipt/witness transmission. While the 1.2 dBi is still the default gain, the chain will now operate using region-specific EIRP to ensure that witness/receipt transmissions are factored correctly. In the EU, transmit power will be reduced to comply with local limits.

Quick math if you have a 5.8 dBi antenna like me: hotspots output at 14 dB for EU. 5.8 dBi – cable loss (0.5 dB) = 5.3 dB. Limit in EU is 16.5 dB. So 14 + 5.3 = 19.3, 19.3 – 16.5 = 2.8 meaning that your miners output power will be reduced by 2.8dB when using a 5.8 dBi antenna in EU with cable loss of .5 dB.

A 2.8dbm reduction is huge. That’s almost half power reduction. In such case a 5.8 dBi would not be as effective as 3 dBi as you are losing a heap of range dropping the power that much without the benfit of the coverage of 3 dBi.”

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