Walsin RF Couplers vs Thin Film Couplers: 17 Parts, Compared Field by Field

Walsin Technology (Walsin) publishes 17 RF coupler part numbers in total — 15 in the Coupler series and 2 in the Thin Film Coupler series. Thirteen are telecom parts covering 617–2700 MHz; four are single-band 2.4 GHz parts. On those four, coupling factor and insertion loss move together in a way you can read straight off the data: 14.6 dB coupling costs 0.32 dB, 6.5 dB costs 1.83 dB.

---

Venatech Limited, an authorised Walsin distributor in Hong Kong, holds Walsin’s RF parametric export. This post is written from it. Every part number below is real. Counts are of part numbers, not pieces. Venatech holds no Walsin RF datasheet PDF, so every specification figure here is read from the export and must be confirmed against Walsin’s own datasheet before design-in. Treat the figures as a shortlist tool, not as a specification.

How many RF couplers does Walsin publish?

Seventeen. Fifteen carry the series name Coupler and two carry Thin Film Coupler.

That number is worth stating plainly, because our own earlier working figure for this line was 30 plus 4. It was wrong. Walsin’s RF folder as we hold it stores every export twice — once under a FRESH_rf_* filename and once under a Walsin_* filename, byte-identical. Summing rows across filenames double-counts the whole RF line: the naive total is 914 parts and the real de-duplicated total is 457. For couplers specifically, Walsin_Coupler.xlsx and FRESH_rf_cpl.xlsx are the same 17 rows, and DataFrame.equals returns true between them.

Split	Part numbers
Coupler series	15
Thin Film Coupler series	2
Total distinct coupler part numbers	17
Telecom application, 617–2700 MHz	13
2.4 GHz BT / Wi-Fi / Zigbee application	4

The rest of the RF line — baluns, filters, multiplexers, antenna switches, BAW and SAW — is covered in Walsin RF: balun, filter, coupler, multiplexer.

What is the difference between the Coupler and Thin Film Coupler series?

In the published data, four things: the package code, the pin arrangement, the coupling factor and the insertion loss. Not the dielectric technology — because the export says both are LTCC.

Category reads LTCC on all 17 rows, including both parts in the series named Thin Film Coupler. Either the series name or the category is wrong, and the data does not say which.

Field	Thin Film Coupler (2 parts)	Coupler (15 parts)	Match / mismatch
Series name	Thin Film Coupler	Coupler	—
Category	LTCC	LTCC	Mismatch with the series name on the thin film parts
Size	605	1608 on all 15	Mismatch — different package
Pin Description	4-LGA	6 on 14 rows, 8 on 1	Mismatch — text against numbers
Impedance (Ω)	50	50	Match on all 17
Band coverage	2400–2500 MHz only	617–2700 MHz and 2400–2500 MHz	Mismatch

Note the Pin Description column: it holds the literal string 4-LGA on the two thin film rows and bare integers 6 and 8 on the other fifteen. One column, two data types, so it cannot be read numerically or matched as a string across the whole file.

What does the 2.4 GHz choice actually look like?

Four part numbers, one band, 50 Ω throughout, and three distinct coupling factors. This is the clearest selection table in the coupler file because every figure is a single number rather than a band-by-band range.

Part number	Series	Package	Coupling in bandwidth	Insertion loss	Pins	Match / mismatch
TFCPL0605B2450T	Thin Film Coupler	0605	14.6 dB	0.32 dB	4-LGA	Tightest coupling, lowest loss
TFCPL0605B24508Q1C	Thin Film Coupler	0605	14.6 dB	0.32 dB	4-LGA	Match — identical to the row above in every published field
RFCPL1810B2450T	Coupler	1608	10.0 ± 1.0 dB	0.74 dB	6	Mismatch — 4.6 dB less coupling, 0.42 dB more loss
RFCPL1806B2450T	Coupler	1608	6.5 dB	1.83 dB	6	Mismatch — 8.1 dB less coupling, 1.51 dB more loss

Two details fall out of that table.

First, TFCPL0605B2450T and TFCPL0605B24508Q1C are identical in every published field. They differ only in the suffix — T against 08Q1C — which on Walsin’s RF parts reads as a packaging or tape-and-reel variant rather than an electrical one. If you have one of the two in a design and cannot get it, the other is the first thing to ask about.

Second, RFCPL1810B2450T is the only one of the four that publishes a tolerance on its coupling factor: 10.0 ±1.0 dB. The other three give a bare number. A ±1 dB coupling window is a real design constraint in a power-detection loop, and its absence on the other three parts is an absence of data, not evidence of a tighter part.

How do I read coupling factor against insertion loss?

As a trade you are making deliberately. A coupler taps a defined fraction of the forward power to a coupled port; the coupling factor is how many decibels down that tap sits. Tighter coupling — a larger dB figure — means less power diverted, so less insertion loss on the through path.

Walsin’s four 2.4 GHz parts show the relationship cleanly:

Coupling factor	Insertion loss	Fraction of forward power at the coupled port	Through-path loss
14.6 dB	0.32 dB	about 3.5%	about 7%
10.0 dB	0.74 dB	10%	about 16%
6.5 dB	1.83 dB	about 22%	about 34%

The percentages are the straight decibel conversions, not Walsin figures. Read them as an illustration of why the two columns move together.

So the selection logic is: if you are sampling forward power for a detector or a closed-loop power control, take the tightest coupling your detector’s sensitivity allows, because the loss you add to the through path is the loss your transmitter pays on every watt. If you need a substantial share of the signal — splitting to a second receive chain, for instance — the 6.5 dB part is the right choice and 1.83 dB is the price.

For the filter in front of that coupler, Choosing an RF chip filter by band covers the band selection. The full line is on the Walsin RF range page.

Why can’t I filter these parts on insertion loss?

Because only 4 of the 17 rows carry a number in that column. The other 13 carry free text, in five different notations.

Notation used inside Insertion Loss (dB)	Rows using it
max. at	12
dB @	9
dB max. at	7
dB max. @	7
dB at	6
Bare number, machine-readable	4 of 17

The telecom parts have a real reason to be multi-line — RFCPL1608070PFT specifies four separate bands from 617 MHz to 2690 MHz, each with its own loss figure, and no single number represents it. The problem is not the content but the inconsistency: the same part family writes the same idea as 0.20 dB @ 698 ~ 960 MHz on one row and 0.20 max. at 698~ 960 MHz on the next, with and without the unit, with and without max., and with both @ and at.

Coupling in BW is the same: a bare number on 3 of 17 rows. And the band string itself splits — the 2400–2500 MHz band is written 2400~2500 MHz with a tilde on the two thin film parts and 2400-2500 MHz with a hyphen on the two Coupler parts. A string match on either form returns two of the four 2.4 GHz couplers and silently misses the other two.

Impedance (Ω) reads 50 on all 17 rows, so it is a field that looks like a selector and discriminates nothing.

Does the Size column tell me the package?

Not reliably. Five of the 17 rows disagree with the four-digit dimensional block in their own part number.

Part number	Block in the part number	Size column	Match / mismatch
RFCPL1807P2S0T62	1807	1608	Mismatch
RFCPL1810B2450T	1810	1608	Mismatch
RFCPL1806B2450T	1806	1608	Mismatch
TFCPL0605B2450T	0605	605	Mismatch — leading zero dropped
TFCPL0605B24508Q1C	0605	605	Mismatch — leading zero dropped
RFCPL1608070P2T	1608	1608	Match
RFCPD1608050PS5T92	1608	1608	Match

The Size column reads 1608 on all 15 Coupler rows regardless of the part number, and 605 on the two thin film rows where the code says 0605. Two of the three mismatching Coupler parts — RFCPL1810B2450T and RFCPL1806B2450T — are in the 2.4 GHz group, which is exactly the group a designer is most likely to be choosing between on footprint.

What do I need to ask Walsin before specifying one?

Four things, because the export does not carry them.

Directivity. It is not a column in the coupler file at all, and it is the figure that decides whether a reflected wave corrupts your forward-power reading. Coupling factor without directivity is half a specification.

Return loss and port VSWR. Also absent. A 50 Ω nominal impedance is published; the match it actually achieves across the band is not.

Power handling. No column. A coupler in a transmit path sees the full forward power, and nothing in the data says how much it will take.

The land pattern, for the three parts above whose Size and part-number block disagree.

That is a substantial list, and it is the honest position: for the Walsin RF line we hold parametric data and no datasheets. We will request the datasheet and the missing figures from Walsin for any coupler part number you name, and we will tell you plainly which of your questions the data we hold can and cannot answer.

The short version

Seventeen coupler part numbers, not 34 — the RF exports are stored twice and summing filenames doubles the line. Fifteen are 1608 telecom parts across 617–2700 MHz; four are single-band 2.4 GHz. On the 2.4 GHz four the trade is explicit: TFCPL0605B2450T at 14.6 dB coupling and 0.32 dB loss, RFCPL1810B2450T at 10.0 ± 1.0 dB and 0.74 dB, RFCPL1806B2450T at 6.5 dB and 1.83 dB. Before you lay out any of them, get the land pattern, because three part numbers disagree with their own Size field. And before you close a power-control loop around one, get the directivity, because it is not published.

Send us the band, the coupling factor and the power level and we will shortlist the Walsin coupler part numbers that fit and request the datasheet for each. Or give us one part number and ask us to cross it.

Check it against the catalogue yourself. Cross-reference accepts one part number or a whole BOM column and prints the mismatches as plainly as the matches — qualification stays with you, which is the honest division of labour. Ready stock covers the RF part lines held in Hong Kong.

---

Frequently asked questions

<!– wp:rank-math/faq-block {"questions":[{"id":"faq-question-01","title":"How many RF couplers does Walsin make?","content":"Walsin's parametric export holds 17 distinct coupler part numbers — 15 in the Coupler series and 2 in the Thin Film Coupler series. Earlier counts of 30 plus 4 came from summing two byte-identical copies of the same export file, which double-counts the whole Walsin RF line from 457 parts to 914.","visible":true},{"id":"faq-question-02","title":"What is the difference between a Walsin Coupler and a Thin Film Coupler part?","content":"In the published data, the package and the performance. The two Thin Film Coupler parts are 0605 with a 4-LGA footprint, 14.6 dB coupling and 0.32 dB insertion loss at 2.4 GHz. The Coupler series parts are 1608 with 6 or 8 pins. Both series are tagged Category = LTCC, which contradicts the thin film name; Venatech has flagged it for confirmation.”,”visible”:true},{“id”:”faq-question-03″,”title”:”Which Walsin coupler has the lowest insertion loss at 2.4 GHz?”,”content”:”TFCPL0605B2450T and TFCPL0605B24508Q1C, both at 0.32 dB with 14.6 dB coupling. The two are identical in every published field and differ only in the part-number suffix. RFCPL1810B2450T is 0.74 dB at 10.0 ± 1.0 dB coupling and RFCPL1806B2450T is 1.83 dB at 6.5 dB.”,”visible”:true},{“id”:”faq-question-04″,”title”:”Why does tighter coupling give lower insertion loss?”,”content”:”Because the coupled port takes its power from the through path. A 14.6 dB coupling factor diverts about 3.5% of the forward power and a 6.5 dB factor diverts about 22%, so the through-path loss rises with the share you tap. Walsin’s four 2.4 GHz parts show the relationship directly, from 0.32 dB at 14.6 dB to 1.83 dB at 6.5 dB.”,”visible”:true},{“id”:”faq-question-05″,”title”:”Can I search Walsin’s coupler data on insertion loss?”,”content”:”Not numerically. Only 4 of the 17 rows carry a bare number; the other 13 are free text in five notations, mixing dB @, dB at, dB max. at, dB max. @ and max. at. The band string splits too — the same 2400 to 2500 MHz band is written with a tilde on two parts and a hyphen on two others.”,”visible”:true},{“id”:”faq-question-06″,”title”:”Does Walsin publish directivity for its RF couplers?”,”content”:”Not in the parametric export. Directivity, return loss, port VSWR and power handling are all absent from the coupler file, and Venatech holds no Walsin RF datasheet. Coupling factor and insertion loss are published; the figures that decide whether a reflected wave corrupts a forward-power reading are not. Request them before design-in.”,”visible”:true},{“id”:”faq-question-07″,”title”:”What footprint does a Walsin RF coupler use?”,”content”:”The Size column reads 1608 on all 15 Coupler rows and 605 on the two thin film rows. But three Coupler part numbers carry 1806, 1807 and 1810 blocks in the code itself, and the thin film code reads 0605 against a Size of 605. Treat the column as unconfirmed and request the land pattern drawing.”,”visible”:true}],”listStyle”:””,”titleWrapper”:”h3″,”titleCssClasses”:””,”contentCssClasses”:””,”sizeSlug”:””} –>

---

---

Three ways to get this answered today

1. Cross a part, free. Paste up to 500 part numbers, or drop an Excel or CSV file, into the free cross-reference tool. It is matched against Walsin’s published catalogue and returns candidates field by field, with every difference from your original stated rather than hidden. Filter by commercial or automotive grade, or for soft termination, high temperature, safety certified, high Q / low ESR or low profile. There is no login and no charge.

2. Send the whole BOM. Upload a BOM and request a quote and we will come back line by line — including the lines we cannot help with, which is usually the more useful half of the answer.

3. Check the shelf before you commit. Ready stock shows what was physically in Hong Kong as at 23 September 2026. It is a dated snapshot, never a live feed, and quantities are never permanent.

Why take our word for any of this? Don’t — check it.

Venatech Limited (威納電子有限公司) is an authorised Walsin Technology distributor in Hong Kong. Confirm that with Walsin rather than with us. On the safety capacitor series we hold UL file E182369, which is searchable in UL’s own public database, together with TUV certificates R50381780 and R50195920 and CQC CQC20001280137 and CQC20001280136, against EN 60384-14:2023, IEC 60384-14:2023 and UL 60384-14. We hold 28 Walsin datasheets, 451 pages, and we will send the one covering your part number. Shipments arrive in original sealed Walsin packaging with lot and date-code traceability, and a certificate of conformity is available per shipment on request.

We will also tell you what we do not hold, which no competitor publishes. REACH, SVHC, conflict minerals, PFAS, China RoHS, ISO 9001, IATF 16949, PPAP, IMDS and a Declaration of Conformity appear nowhere in those 451 pages. You would rather hear that from us now than from your own supplier-approval team later. AEC-Q200 is compliant in Walsin’s own words and never certified, we hold no manufacturer’s end-of-life or allocation list for any brand, and qualification in your own circuit stays with you. We will not tell you a part is equivalent. We will show you where it differs.

Venatech Limited · Unit 207, 2/F, Sun Ling Plaza, 30 On Kui Street, Fanling, N.T., Hong Kong · (852) 2628 4777 · Hong Kong, Shenzhen, Singapore and Jiangmen, with Chengdu in preparation.