PCB Antenna
A 2.4 GHz antenna etched directly onto the PCB, commonly used in BLE designs for cost and size optimization.
PCB Antenna
A PCB antenna is a 2.4 GHz antenna implemented as a copper trace pattern etched directly onto the printed circuit board. It is the most cost-effective antenna solution for BLE products, adding zero BOM cost beyond the PCB itself. PCB antennas are widely used in beacons, sensors, wearables, and other size-constrained BLE devices.
Common PCB Antenna Types
| Type | Size | Performance | Design Complexity |
|---|---|---|---|
| Inverted-F (IFA/PIFA) | 10-15 mm | Good | Medium |
| Meandered monopole | 8-12 mm | Good | Medium |
| Meandered dipole | 15-25 mm | Better | Higher |
| Loop antenna | 10-15 mm | Moderate | Low |
| Ceramic patch (hybrid) | 5-8 mm | Good | Low |
The Inverted-F Antenna (IFA) is the most popular choice for BLE products due to its compact size, reasonable bandwidth, and well-documented reference designs from chip vendors like Nordic and Espressif.
Design Considerations
PCB antenna performance depends heavily on layout:
- Ground plane clearance: The antenna element requires a keep-out zone (typically 5-10 mm) free of copper pour on all PCB layers. Violating this clearance detunes the antenna and degrades RSSI
- Board edge placement: Antennas perform best at the PCB edge, away from battery, LCD, and metal enclosure walls
- Impedance matching: A pi-network (two capacitors + inductor) between the SoC RF output and antenna trace tunes the impedance to 50 ohms. Chip vendors provide reference matching networks
- Enclosure effects: Plastic enclosures detune the antenna by 50-200 MHz. Production matching must be done with the final enclosure
PCB Antenna vs Chip Antenna
| Parameter | PCB Antenna | Chip Antenna |
|---|---|---|
| BOM cost | $0 (part of PCB) | $0.10-0.50 |
| PCB area | 10-25 mm trace | 2-5 mm component |
| Performance | Layout-dependent | More consistent |
| Design effort | RF expertise needed | Place-and-route |
| Ground clearance | Required | Required |
When to Choose PCB Antenna
PCB antennas are ideal when cost is critical and PCB area is available (at least 10 mm edge clearance). For products with tight PCB constraints, metal enclosures, or limited RF expertise, a Chip Antenna or pre-certified Module with integrated antenna is safer. Reference designs from SoC vendors (Nordic, Espressif, TI) provide validated PCB antenna layouts that can be copied directly.
Related Terms
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