Yagi vs Omni for the WisBlock Unify Outdoor Enclosure

Development Hardware
1

Here are two possible LoRa antennas for a fixed, outdoor, mast deployment:

https://www.aliexpress.us/item/3256806477712043.html

https://www.aliexpress.us/item/3256806532903775.html

Both provide 8 dBi gain. Which is better for urban Meshtastic applications?

I think that the Yagi antenna is generally preferred. The key reason is that the Yagi antenna can provide SNR improvement by pointing away from the city center. You likely can tie to the city mesh via close/local nodes, but by pointing the Yagi antenna out to the periphery of the city mesh, you can likely expand the coverage of the mesh in that direction without providing high gain to city noise sources.

Also note that the omni antenna has a very flat beam pattern. If you mount your omni antenna high up, you may not see nodes that are close-by but low to the ground.

Also note that cities likely have many potential multipath reflectors that can degrade transmit and receive signals. Pointing away from the city can reduce the channel fading caused by multipath interference. With a spreading factor of 11 (the default), this should not be a problem generally.

A key motivation for me is to try to provide a bridge to a nearby city with a minimum number of hops. A Yagi antenna provides both transmit and receive gain, specifically in the preferred direction.

2

I don’t think there is a ‘general’ answer here.

Will depend on the local circumstances. In some cases it can be that most of the nodes you would want to contact are in a specific direction, so a directional Yagi can be beneficial.

A ‘bridge’ to a nearby city does sound like something for a directional antenna.

But if the contacts are not in a specific directions, then a omni would probably be better. You probably get some ‘leakage’ even with a directional one, that might get away with either for some contacts.

3

I am pitching a different approach to Yagi deployment:

I currently have a 5 dBi omni antenna on a static deployment at my house. I can see over 100 nodes from that Meshtastic node.

I really don’t think that my node adds much. The interconnectivity to my node is so extensive, that if my node went away, there would be no significant loss to the local mesh.

How do I make my node more helpful? Is there some way that I can use my node to make the mesh more robust, or just larger?

I know that Yagi antennas, being directional, are deployed typically to point toward something. But what if I choose instead to deliberately point away from my local mesh, specifically with the intent of making the mesh bigger?

In my case, that happens to be attempting to bridge to another city. But what if I fail in that goal, but instead, just connect to distant nodes that makes my local grid larger? Isn’t that still a noble outcome?

Since people typically don’t think in these terms, they just deploy omni antennas. But in a dense, urban setting, should people be normally be deploying Yagi antennas instead, specifically in ways that enhances the local mesh?

Note that connecting to “nodes you would want to contact” would likely not be impaired, since even if they are not in the direction that the Yagi is pointed, you likely can still hop to your target nodes.

Note that the beam pattern with an 8 dBi Yagi with 4 parasitic elements has considerable ‘leakage’:

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So you are likely to pick up many nodes along the direct bearing.

4

They seem the same thing to me. Just phrased differently.

By pointing away from the mesh, you are pointing towards opportunity. You are pointing towards more remote nodes.

You do seem to be making a great case for a directional antenna. Seems you have a ‘viable’ reason to point in a specific direction.

But it wouldnt be appropriate in all cases, if meshes where only made of directional, then might be harder to get local contact. But would depend on the exact configuration, would technically be possible for a fully interconnected mesh only made of directional.

Sometimes, couldnt pick a specific direction, so omni would be a good all round comprimise.

Which is why still say both are appropriate in different circumstances.