Model: TX433-TH-3
Type: Helical spring antenna
Frequency: 433 MHz (ISM band, 420–450 MHz)
Impedance: 50 Ω
Gain: 1 dBi (omnidirectional)
VSWR: ≤1.5 @ 433 MHz
Mount / Interface: Direct PCB solder (through-hole welding)
Polarization: Vertical, linear
Compatible Modules: Ebyte E30-433T20D, E22-400T22S, E220-400T22S, and all 433 MHz RF modules with 50Ω antenna port
Applications: IoT sensor nodes, smart metering, agricultural telemetry, asset tracking, industrial wireless
| 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 | ≤1.5 | Measured at 433 MHz |
| Max. Input Power | 1 W (30 dBm) | Continuous |
| Radiation Pattern | Omnidirectional | 360° horizontal coverage |
| Polarization | Vertical, linear | — |
| Mount Type | PCB solder (through-hole) | Direct welding, no connector |
| Operating Temp. | −40 to +85 ℃ | Industrial grade |
| Compliance | RoHS | Lead-free materials |
VSWR ≤1.5 — Superior Impedance Match for Maximum Range
The TX433-TH-3 achieves a VSWR of ≤1.5 at 433 MHz, indicating a return loss better than −14 dB and reflected power below 4%. This tighter VSWR specification (vs. the typical ≤2.0 of generic spring antennas) means more of your module’s transmit power reaches the antenna and radiates effectively — directly translating to longer link range and more reliable reception in IoT deployments where every dB matters.
50Ω Direct Solder Mount — Zero Connector Loss, Maximum Mechanical Reliability
The TX433-TH-3 solders directly to a PCB through-hole pad at the 50Ω antenna point, eliminating the 0.2–0.5 dB insertion loss of SMA or IPEX connectors. The helical spring structure absorbs mechanical shock and vibration without cracking the solder joint — a critical advantage in mobile, automotive, and industrial deployments subject to continuous vibration. No connector means no connector corrosion or intermittent contact failures over the product lifetime.
Compact Helical Design — Full 433 MHz Performance in Minimal PCB Space
The coiled spring geometry resonates at 433 MHz in a fraction of the 17.3 cm quarter-wave whip length, enabling integration into compact enclosures and dense PCB layouts. The omnidirectional radiation pattern ensures 360° horizontal coverage, so link quality is maintained regardless of node orientation — essential for rotating equipment, mobile assets, and randomly deployed sensor nodes.
Ideal Applications
Frequently Asked Questions
Q: What is the difference between the TX433-TH-3 and SW433-TH32DN?
A: Both are 433 MHz through-hole spring antennas with 50Ω impedance and 1 dBi gain. The TX433-TH-3 specifies VSWR ≤1.5 (tighter match), while the SW433-TH32DN is rated VSWR ≤2.0. Physical dimensions and wire gauge may differ slightly. Both are direct PCB solder mount and compatible with the same Ebyte RF modules.
Q: Is the TX433-TH-3 compatible with Ebyte E30-433T20D and E22-400T22S modules?
A: Yes. Both modules present a 50Ω antenna port. Solder the TX433-TH-3 spring base to the antenna pad and surrounding ground ring on your PCB. The VSWR ≤1.5 ensures minimal reflected power back into the module’s PA stage.
Q: What PCB pad design should I use for the TX433-TH-3?
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 ground plane clearance of at least 3 mm around the antenna base to avoid detuning. Refer to the Ebyte TX433-TH-3 datasheet for the recommended PCB footprint and keep-out zone.
Q: Can I use this antenna outdoors?
A: The antenna element operates from −40 to +85℃ and is suitable for industrial temperature ranges. For outdoor deployment, house the PCB in an IP65 or higher rated enclosure to protect against moisture, UV, and condensation.
Q: What is the maximum transmit power this antenna can handle?
A: The TX433-TH-3 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). There is no risk of antenna damage under normal operating conditions.
