Choose a 2.4 GHz chip antenna on four things: band coverage, physical envelope, peak gain
and VSWR. Walsin Technology (Walsin) lists 12 chip antennas, eleven of them covering
2.4~2.5 GHz. Most deliver 2 dBi peak gain at VSWR 2.0 maximum. Length ranges from 3.2 mm to
19 mm. The board matters as much as the part.
What do I actually specify when choosing a 2.4 GHz chip antenna?
Start with the band. Then take the largest rectangle you can give up on the board edge,
because antenna performance tracks volume and clearance. Then read peak gain and VSWR from
the datasheet as the manufacturer’s best case on their evaluation board. Your ground plane
and enclosure will move both numbers.
A chip antenna is not a self-contained radiator. It is a resonant structure that borrows
the board’s ground plane as its counterpoise. Two designs using the same part can differ by
several dB because one has a full ground plane behind the feed and a clear keep-out, and the
other has a battery sitting 2 mm away.
That is why the selection sequence is envelope first, part second, matching network third.
Which Walsin chip antennas cover 2.4 GHz?
Eleven parts cover 2.4~2.5 GHz, one covers 2.4~2.55 GHz, and two of the eleven are dual-band
parts that also cover 4.9~5.9 GHz. All of them are supplied under the Chip Antenna
(BT, Wi-Fi band) series. The choice inside that group is essentially a choice of physical
envelope.
Here are seven real Walsin parts compared against a common reference. The right-hand column
states what matches and what does not, field by field. No part here is a drop-in for
another — the footprints differ.
| Walsin part number | Band | Dimension (mm) | Peak gain | VSWR (max) | Match / mismatch vs RFANT3216120A1T |
|---|---|---|---|---|---|
| RFANT3216120A1T | 2.4~2.5 GHz | 3.2 x 1.6 x 1.2 | 2 dBi | 2.0 | reference part |
| RFECA3216060A1T | 2.4~2.5 GHz | 3.2 x 1.6 x 0.6 | 2 dBi | 2.1 | match: band, length, width, peak gain · mismatch: 0.6 mm height not 1.2 mm, VSWR 2.1 not 2.0, different series prefix |
| RFANT5220110A0T | 2.4~2.5 GHz | 5.2 x 2 x 1.1 | 2 dBi | 2.0 | match: band, peak gain, VSWR · mismatch: longer and wider, 1.1 mm height, different footprint |
| RFANT8010080A3T | 2.4~2.5 GHz | 8 x 1 x 0.8 | 2 dBi | 2.0 | match: band, peak gain, VSWR · mismatch: 8 mm long, only 1 mm wide, 0.8 mm high — a narrow-strip envelope, not a chip envelope |
| RFANT9520120A0T | 2.4~2.5 GHz | 9.5 x 2 x 1.2 | 2 dBi | 2.0 | match: band, peak gain, VSWR, 1.2 mm height · mismatch: 9.5 mm long, 2 mm wide |
| RGFRA9937380A3T | 2.4~2.55 GHz | 9.9 x 3.7 x 3.8 | 2 dBi | 2.0 | match: peak gain, VSWR · mismatch: band extends to 2.55 GHz, 3.8 mm tall, far larger volume, different series prefix |
| RFANT6050110L0T | 2.4~2.5 GHz and 4.9~5.9 GHz | 5.9 x 5.1 x 1.1 | 4 dBi | 2.0 | match: VSWR, lower band covered · mismatch: dual band, 4 dBi not 2 dBi, 5.1 mm wide, different footprint entirely |
Source: Walsin product index — https://www.passivecomponent.com/products/ (product
index, not a per-part datasheet).
Does a bigger chip antenna give more gain?
Not in this catalogue, and that surprises people. RFANT3216120A1T at 3.2 x 1.6 x 1.2 mm
and RGFRA9937380A3T at 9.9 x 3.7 x 3.8 mm both specify 2 dBi. What the larger part usually
buys is bandwidth margin and tolerance to a less-than-ideal ground plane, not headline gain.
The single part in the range that specifies higher gain is the dual-band pair
RFANT6050110L0T and RFANT6050110L1T at 4 dBi. Those also cover 4.9~5.9 GHz in addition
to 2.4~2.5 GHz. If you are designing single-band 2.4 GHz only, you are choosing between
parts that all claim the same peak gain, so the decision comes down to the envelope you can
give up and the keep-out you can maintain.
Treat peak gain as a ceiling, not a promise. It is measured on a reference board.
How do I place a chip antenna on the board?
Put it on a board edge, ideally a corner. Give it the keep-out the datasheet drawing
specifies — no copper on any layer under or beside the element. Keep the feed line 50 Ω and
short. Put a matching pi-network footprint next to the feed, even if you expect to fit
zero-ohm links.
Three further rules that recover most of the performance people lose:
- Do not route signals or place metal in the keep-out, including on inner layers and the
bottom layer. The keep-out is three-dimensional. - Keep batteries, shield cans, displays and metal enclosure walls away from the element. A
metal enclosure wall near a chip antenna detunes it, and no matching network fully
recovers that. - Give the ground plane a clean, continuous edge adjacent to the antenna. The plane is part
of the radiator.
Always fit the pi-network. The part is characterised on the manufacturer’s board, not
yours, and you will need one or two components to pull the resonance back on frequency.
When should I use a PCB or FPC antenna instead?
Use a PCB or FPC antenna when you have length but not thickness, or when you need the
radiator away from a dense board. Walsin’s antenna range includes six PCB antennas and
three FPC antennas alongside the 12 chip antennas, plus dipole, metal, NFC and WPC types.
RFPCA460605NNAB301 is a 46.5 x 6 x 2.1 mm PCB antenna covering 2.4~2.5 GHz at greater
than 3 dBi. RFPCA500609IMAB301 is 50 x 6.2 x 3 mm covering the same band at greater than
4 dBi. Both beat every 2.4 GHz chip antenna in the range on gain, and both cost you 46 mm
or more of linear space.
RFFPA202506IMAB301 is an FPC antenna at 20.45 x 25.9 x 0.103 mm covering 2.4~2.5 GHz at
greater than 3 dBi. At 0.103 mm thick it can be adhered to the inside of an enclosure wall,
well away from the PCB. That freedom is usually worth more than a decibel of catalogue gain.
The whole antenna range is 44 parts across ten series: 12 chip antenna, seven dipole
(N/SMA), six dipole (cable), six PCB, three FPC, three cable assembly, three connector, two
metal, one NFC and one WPC.
What does VSWR 2.0 max actually mean for my design?
VSWR 2.0 corresponds to a return loss of about 9.5 dB, meaning roughly 11% of incident power
is reflected back to the transmitter. It is the normal acceptance limit for a consumer
2.4 GHz radio. Every 2.4 GHz chip antenna in Walsin’s range specifies 2.0 maximum except
RFECA3216060A1T, which specifies 2.1.
That single-digit difference is not a reason to reject a part. It is a reason to read the
whole row. RFECA3216060A1T is half the height of RFANT3216120A1T at the same length and
width. In a device with a 1 mm internal clearance, the 0.6 mm part is the only one that
fits, and the VSWR difference is inside the variation your own board will introduce anyway.
One thing worth knowing before you count Walsin’s antenna range
Walsin’s on-site product counter for antennas includes the header row of the underlying
table. The displayed figure therefore reads one higher than the number of real orderable
parts. The same off-by-one applies to the RF and MOV counters. Our own extraction, counted
part by part, gives 44 antenna parts.
Venatech Limited, an authorised Walsin distributor in Hong Kong, holds that extracted data
set and can filter it by band, envelope, gain and VSWR on request.
Flagged for review: the Working Frequency Range field on
RFANT6050110L0Tand
RFANT6050110L1Tarrives from Walsin’s export with the two bands separated by run-on
whitespace rather than a delimiter. We have read this as 2.4~2.5 GHz plus 4.9~5.9 GHz.
Confirm against the drawing before publishing the dual-band claim in a customer document.
Frequently asked questions
Can I swap one Walsin 2.4 GHz chip antenna for another without changing the layout?
No. Every part in the range has a different footprint and a different keep-out.
RFANT3216120A1T is 3.2 x 1.6 x 1.2 mm and RFANT9520120A0T is 9.5 x 2 x 1.2 mm. The
electrical specifications happen to match at 2 dBi and VSWR 2.0, but the mechanical
mismatch means a new layout and a new matching network.
What is the difference between RFANT3216120A1T, A3T and A5T?
The parametric fields are identical: 2.4~2.5 GHz, 3.2 x 1.6 x 1.2 mm, 2 dBi, VSWR 2.0
maximum. The differentiation sits in the suffix, which the export does not explain. Ask us
to confirm the packaging or variant meaning before you order one rather than another.
Do I still need a matching network with a chip antenna?
Yes. Fit a pi-network footprint next to the feed on every design. The catalogue figures are
measured on a reference board with a defined ground plane. Your board will resonate slightly
off. One or two components brings it back, and populating them with zero-ohm links costs
nothing if it turns out you do not need them.
Which part should I pick for a dual-band Wi-Fi product?
RFANT6050110L0T or RFANT6050110L1T. Both cover 2.4~2.5 GHz and 4.9~5.9 GHz in a
5.9 x 5.1 x 1.1 mm body at 4 dBi peak gain and VSWR 2.0 maximum. They are physically wider
than the single-band parts, so allocate the area at schematic stage rather than at layout.
Is peak gain the number I should design the link budget around?
No. Peak gain is the maximum over the radiation pattern, measured under reference
conditions. Design the link budget around realised gain in your enclosure, in the
orientation the product is actually used. Treat the catalogue figure as the best case you
will not quite reach.
Can a chip antenna be placed in the middle of the board?
It can be placed there, but it will perform badly. A chip antenna needs a board edge and a
clear keep-out because the ground plane acts as its counterpoise and surrounding copper
detunes and absorbs. If the mechanical design forces a central position, use an FPC antenna
on a cable and mount the radiator at the enclosure wall.
Does Walsin offer antennas outside 2.4 GHz?
Yes, across other series. The range includes GNSS parts such as the FPC antenna
RFFPA401410IMGB301 at 1559~1609 MHz, sub-GHz metal antennas such as RFMTA010504NNRB002
at 863~928 MHz, an NFC antenna RFNFC355500NNNB001 at 13.56 MHz, and a WPC antenna
RFWPC483246NNPBC01 at 100 kHz.
Next step
Send us the envelope you can give the antenna, the band, and a picture of the enclosure
around it. Venatech Limited will return the Walsin parts that physically fit, with band,
dimension, peak gain and VSWR stated field by field and every mismatch marked. We will not
tell you a part is equivalent to the one in your current design. We will show you exactly
which fields differ so you can decide whether the layout change is worth it.
Send us your BOM → · Browse Walsin antennas →
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Walsin RF components: balun, filter, coupler and multiplexer ·
High-Q, low-ESR MLCC for RF