Macrobend loss is additional optical loss associated with a defined bending arrangement. To interpret a specification, retain the bend radius, number of turns, wavelength and allowed loss together. The G.657 reference products on this site use several different arrangements, so the dB figures should not be ranked as though they came from the same experiment. A smaller test radius is relevant information, but it is not the minimum installation radius of every cable made from that fiber. Finished-cable construction and handling requirements must be confirmed separately. For a project comparison, state the bend condition the fiber must meet and ask for the offered supplier specification or applicable evidence for that condition.
Four fields define a useful bend-loss entry
A complete entry includes radius, turns, wavelength and loss. Radius describes the bend arrangement; turn count describes how much of that arrangement is applied; wavelength identifies the optical test condition; the loss figure states the result or limit. Omitting any field makes the comparison less precise.
If a supplier gives a bend-performance claim without the arrangement, ask for the missing conditions. Do not fill the gap by copying conditions from another product or a general illustration.
Read the reference conditions as separate tests
The product data include an A1 test at 15 mm with ten turns, A2 tests at 10 mm and 7.5 mm with one turn, and B3 tests at 5 mm with one turn. The diagram organizes these published conditions. It is not a measured loss curve and does not establish how a single sample would perform at every radius.
For loss limits, use the linked product tables and their stated wavelengths. A direct procurement comparison should address a shared project requirement; request that condition explicitly if it is absent.
Separate fiber tests from cable installation rules
An installed cable includes a construction and handling process that the bare-fiber optical test does not describe. Ask for the finished cable instructions and the route conditions, including any restrictions associated with installation tension. Do not convert a small-radius reference test into a general permission to bend an assembled cable to that radius.
When preparing an RFQ for coated fiber, state both the relevant optical test requirement and the cable design context. This gives the supplier a precise question while preserving the distinction between fiber selection and finished-cable qualification.
What to confirm
- Radius in mm
- Number of turns
- Wavelength in nm
- Additional loss in dB
- Source specification and revision
- Separate cable installation limits
Frequently asked questions
Are a one-turn and ten-turn test directly comparable?
They use different arrangements. Keep turn count visible and ask for a shared required condition if a direct comparison is needed.
Can I calculate the loss at an unlisted radius from these tables?
The tables do not provide a measured curve for interpolation. Request an applicable specification or test result.
Does bend-insensitive mean there is no bend loss?
No. Read the published limits and conditions; the description does not mean zero loss under every arrangement.
Sources & reference context
This guide is published by OpticFiberHub and summarizes the supplier literature identified below with editorial purchasing guidance. Product values describe the source grade, not a measured result or a conformity guarantee for a new order.
- G.657.A1 reference specifications — BendCom G.657.A1 Bending Insensitive Single-mode Optical Fiber datasheet, pages 1–2.
- G.657.A2 reference specifications — Jiangsu Nanfang Optical Fiber Product Manual, pages 7–8.
- G.657.B3 reference specifications — Jiangsu Nanfang Optical Fiber Product Manual, pages 9–10.
Quality & technical resources explains source selection, translated documents and the limits of historical batch records. Request the current specification and applicable records for the actual offered material.
Further terminology reference: The Fiber Optic Association: optical fiber fundamentals.
Single-mode standard references: ITU-T G.652 and ITU-T G.657. Supplier reference values above must not be mistaken for a reproduction of every requirement in those Recommendations.
