Model: SW433-TH32DN
Frequency: 433 MHz (ISM band, 420–450 MHz)
Impedance: 50 Ω
Gain: 1 dBi (omnidirectional)
Connector / Mount: Through-hole (TH) spring, direct PCB solder
Polarization: Vertical, linear
Compliance: RoHS
Compatible Modules: Ebyte E30-433T20D, E22-400T22S, E220-400T22S, and all 433 MHz UART/SPI RF modules with 50Ω antenna port
| Parameter | Value | Remark |
|---|---|---|
| Center Frequency | 433 MHz | ISM band, 420–450 MHz usable |
| Impedance | 50 Ω | Standard RF impedance |
| Gain | 1 dBi | Omnidirectional, vertical polarization |
| VSWR | ≤2.0 | Measured at 433 MHz |
| Max. Input Power | 1 W (30 dBm) | Continuous |
| Radiation Pattern | Omnidirectional | 360° horizontal coverage |
| Polarization | Vertical, linear | — |
| Mount Type | Through-hole (TH) | Direct PCB solder, no connector |
| Operating Temp. | −40 to +85 ℃ | Industrial grade |
| Compliance | RoHS | Lead-free materials |
50Ω Impedance Matching — Maximum Power Transfer to Your RF Module
The SW433-TH32DN is wound and tuned to present a 50Ω impedance at 433 MHz, matching the standard output impedance of all Ebyte RF modules (E30, E22, E220 series) and virtually all commercial 433 MHz transceivers. Proper impedance matching minimizes reflected power (VSWR ≤2.0), ensuring the full transmit power reaches the antenna and maximizing effective range without additional matching components.
Through-Hole PCB Mount — Mechanically Robust, No Connector Loss
The spring antenna solders directly to a PCB through-hole pad, eliminating the connector insertion loss (typically 0.2–0.5 dB) associated with SMA or IPEX connectors. The helical spring structure provides mechanical flexibility, absorbing vibration and shock in industrial and mobile deployments without cracking solder joints — a common failure mode for rigid stub antennas.
Compact Helical Design — Space-Efficient for Embedded IoT Nodes
The coiled spring geometry achieves a resonant 433 MHz antenna in a fraction of the length of a quarter-wave whip (17.3 cm). This makes the SW433-TH32DN ideal for compact enclosures, sensor nodes, and PCB designs where board space is constrained, while maintaining omnidirectional coverage for reliable link establishment in all directions.
Ideal Applications
Frequently Asked Questions
Q: Is the SW433-TH32DN compatible with Ebyte E30-433T20D and E22-400T22S modules?
A: Yes. Both modules use a 50Ω antenna port. The SW433-TH32DN is designed for direct PCB integration alongside these modules. Solder the spring base to the antenna pad and ground ring on your PCB for optimal performance.
Q: What is the difference between a spring antenna and an SMA stub antenna at 433 MHz?
A: A spring (helical) antenna is mechanically flexible and mounts directly to the PCB without a connector, saving space and eliminating connector loss. An SMA stub antenna is rigid and requires a connector but is easier to replace. For embedded, high-vibration, or space-constrained designs, the spring antenna is preferred.
Q: Can I use this antenna outdoors?
A: The antenna element itself operates from −40 to +85℃ and is suitable for industrial environments. For outdoor deployment, ensure the PCB and antenna are housed in an IP-rated enclosure to protect against moisture and UV exposure.
Q: What PCB pad size and footprint should I use?
A: Use a through-hole pad matching the spring wire diameter (typically 0.8–1.0 mm drill, 1.6 mm annular ring) with a surrounding ground plane clearance of at least 3 mm to avoid detuning the antenna. Refer to the Ebyte SW433-TH32DN datasheet for the recommended PCB footprint.
Q: What is the maximum transmit power this antenna can handle?
A: The SW433-TH32DN is rated for up to 1 W (30 dBm) continuous input power, which exceeds the maximum output of all standard Ebyte 433 MHz modules (20 dBm / 100 mW), so there is no risk of antenna damage under normal operating conditions.
