# Antenna

## Supported Frequencies

Zentanode operates on region-specific frequencies for optimal performance and regulatory compliance.

| Frequency | Region                                 |
| --------- | -------------------------------------- |
| 868 MHz   | Europe, Switzerland, South Africa, UAE |
| 863 MHz   | Ukraine, Turkey, Saudi Arabia          |
| 865 MHz   | India                                  |
| 864 MHz   | Russia                                 |
| 902 MHz   | US, Canada, Mexico                     |
| 915 MHz   | Asia, Australia                        |
| 920 MHz   | Hong Kong                              |
| 922 MHz   | Latin America, Southeast Asia          |
| 470 MHz   | China                                  |

{% hint style="info" %}
Verify the correct MHz specification for your country before purchasing. If you have purchased an incorrect frequency version, contact [zentanode.com](https://zentanode.com) for a replacement.
{% endhint %}

***

## Antenna Performance

Performance characteristics across key frequency bands:

| Frequency (MHz) | Gain (dBi) | Efficiency (%) | Beamwidth | VSWR  |
| --------------- | ---------- | -------------- | --------- | ----- |
| 600             | 2.63       | 32.2%          | 65°       | 1.5:1 |
| 680             | 2.19       | 34.3%          | 70°       | 1.6:1 |
| 760             | 1.44       | 40.0%          | 85°       | 1.5:1 |
| 840             | 2.31       | 38.5%          | 75°       | 1.6:1 |
| 868             | 2.76       | 44.1%          | 60°       | 1.3:1 |
| 915             | 2.79       | 45.2%          | 55°       | 1.2:1 |

***

## Key Parameters

| Parameter    | Description                                                 |
| ------------ | ----------------------------------------------------------- |
| Gain (dBi)   | Ability to focus and amplify signal in a specific direction |
| Efficiency   | Ratio of radiated power to input power                      |
| Beamwidth    | Angular width of the main radiation lobe                    |
| VSWR         | Voltage Standing Wave Ratio — lower is better (1.0 = ideal) |
| Polarization | Linear (all Zentanode frequencies)                          |

***

## Range Estimation

Under ideal line-of-sight conditions, the theoretical range can be estimated using the Friis transmission equation:

```
Pr = Pt + Gt + Gr - 20*log10(d) - 20*log10(f) - 32.44
```

| Variable | Description           | Zentanode Value |
| -------- | --------------------- | --------------- |
| Pt       | Transmit power        | 10 dBm          |
| Gt       | Transmit antenna gain | 3 dBi           |
| Gr       | Receive antenna gain  | 3 dBi           |
| f        | Frequency             | 900 MHz         |
| Pr(min)  | Receiver sensitivity  | -100 dBm        |

**Result: approximately 8.6 km range under ideal conditions.**

{% hint style="warning" %}
Real-world range is typically lower due to obstructions, terrain, and multipath fading. The practical operating range of a Zentanode is up to 6 km. Mesh networking with multiple nodes can extend overall coverage.
{% endhint %}

***

## Optimizing Range

* **Placement** — Mount the antenna elevated and away from metal objects, walls, and dense foliage. Line-of-sight to other nodes significantly improves range.
* **Node Density** — Add more Zentanodes to extend coverage through multi-hop mesh routing. Each node acts as a relay.
* **Cable Quality** — Use high-quality, short coaxial cables to minimize signal loss.
* **Grounding** — Proper grounding reduces interference and improves performance.
* **Environment** — Temperature extremes, humidity, and electromagnetic interference can affect antenna performance.