LoRa Antenna Gain vs Height — What Actually Boosts Link Performance

#iot #learning #networking #systemdesign

This is an excerpt.

Read the full technical analysis:
https://www.vladavramut.com/articles/lora-antenna-gain-vs-height.html

When planning LoRa and Meshtastic deployments, antenna discussion quickly focuses on gain — higher is better, right?

Not quite.

Real-world performance is dominated by antenna height and Fresnel zone clearance, not just gain figures on a datasheet.

Antenna gain matters — but only when the antenna is placed such that its radiation pattern can actually propagate unobstructed.

This excerpt clarifies what really moves the needle in field deployments.

Antenna Gain: What It Does and Doesn’t Do

Antenna gain describes how effectively an antenna directs radiated power in certain directions.

Higher gain can:

• narrow the main lobe

• push more energy along a specific axis

• improve link budget in that direction

But higher gain also:

• narrows the beamwidth

• reduces coverage in other directions

• amplifies multipath nulls

In practice, a high-gain antenna mounted low with obstructions offers worse range than a low-gain antenna mounted high with clear line-of-sight.

Height and Fresnel Zone Dominate Path Loss

For sub-GHz links like LoRa, the first Fresnel zone radius at typical ranges quickly becomes several meters.

If this zone is partially blocked by terrain, structures, or vegetation:

• diffraction losses increase

• effective signal strength drops

• link reliability collapses

Raising the antenna improves:

• direct line-of-sight

• Fresnel clearance

• link margin

Often, 10–20 m of height shifts performance more than several dB of antenna gain.

Practical Field Observations

Multiple field tests show:

• low antenna with high gain underperforms

• modest gain with high placement consistently outperforms

• horizontal polarization interacts differently with ground reflection

Engineers who equate gain numbers with link quality without considering height tend to design networks that fail in the field.

Physics Before Part Numbers

The lesson for real deployments is straightforward:

Optimize placement before optimizing gain.

Antenna height and obstruction analysis deliver predictable performance improvements.

Gain tweaks often deliver marginal effects — and rarely more than a well-placed antenna.

Continue reading the full technical analysis:
https://www.vladavramut.com/articles/lora-antenna-gain-vs-height.html