At only 55% of the size of the U.FL connector series, the W.FL Series is one of the world's smallest radio frequency connectors. This micro-miniature connector produced by Hirose is a space-saving solution for introducing wireless connectivity into densely packed electronic circuits. This short guide provides you with the essentials of W.FL connectors and cables and their common applications.
What is a W.FL connector?
W.FL is a Micro-Miniature, lightweight coaxial connector made by Hirose Electric Group, a Japanese electronics company. It is also known as an Ultra Small Surface Mount Coaxial Connector. The connector has a frequency range of 0 - 6 GHz from DC and an impedance of 50 Ohms. W.FL occupies a mounting area of 3.4 mm square and is extremely lightweight, with a fully mated height of only 1.4mm.
W.FL connectors feature a user friendly tactile click when successfully coupled. W.FL plugs are terminated only using ultra-fine coaxial cables with fluorinated resin insulation. Termination is done using specialized tools.
The W.FL connector is in many aspects a smaller version of the Hirose U.FL connector, a standard in the wireless networking industry due to its extremely small mounting area. It is used in printed circuit boards PCBs with its jack being board-mounted. The scaling down of the W.FL connector achieves a massive reduction in the board space occupied by the connector.
Physical specifications of the W.FL connector
The W.FL comprises a female plug connector and a male jack with surface mount technology (SMT) that can be mounted directly onto a circuit board. The male being placed directly on top of the female connector mates them. This is best done with a special mating and unmuting tool that ensures that the connector is properly connected and disconnected. W.FL connectors feature a user-friendly tactile click when successfully coupled. W.FL plugs are terminated only using ultra-fine coaxial cables with fluorinated resin (Teflon) insulation.
The W.FL connector has a mated height of 1.4 mm (max 1.55mm). Its mated weight is 5.6mg for the receptacle and 18.6 mg for the plug.
The W.FL plug has a right-angle orientation. It dimensions are 2.12 mm (width) by 1.38 mm (height) by 3.65 mm (length). The shell of the plug is made from silver-coated phosphor bronze and the inner receptacle is made from gold-plated phosphor bronze. The center contact is female. Within the connector, there is a small amount of polybutylene terephthalate (PBT), a semi-crystalline engineering thermoplastic, as a dielectric material.
W.FL plugs are always supplied as cable assemblies. They cannot be exchanged. It uses ultra-fine, fluorinated resin-insulated coaxial cable, as it facilitates using the connector in compact and confined environments.
The PCB-mounted W.FL receptacle has dimensions of 2 mm (length) by 2mm (width) and a height of 0.85 mm. Its shell is made from silver-plated phosphor bronze and its inner connector pin is made from brass. The center contact is male and is surrounded by a liquid crystal polymer dielectric. The W.FL receptacles are supplied on a tape and reel and can be located on a PCB using the vacuum nozzles of the automatic placement equipment.
The W.FL connector is minute and fragile and cannot withstand repeated connection and disconnection. It is only rated for 20 mating cycles.
W.FL connector electrical specifications
- Impedance: The W.FL connector has a nominal impedance of 50 Ohm
- Frequency range: The W.FL connector is a microwave connector that has a frequency range of DC to 6 GHz
- VSWR:. 1.3 max (up to 3 GHz) 1.4 max (3 GHz to 6 GHz)
- Contact resistance: At the center contact the resistance is 20 megohms max
- Insulation resistance: The insulation resistance is 500 megohms
W.FL cable assemblies
W.FL cables can only be made with the very thin and flexible coaxes such as 1.13 or thinner. W.FL is not compatible with larger coaxes like LMR100 and RG178. The thinnest cable that we can make W.FL cables with is 0.81mm (so 0.66mm is not an option for W.FL cables). Here are the most common coaxial cables used for W.FL connector cables:
|Coax diameter (mm)||Inner conductor diameter (mm)||Insulator diameter (mm)||Outer conductor shielding||Jacket diameter (mm)||Impedance (ohms)|
Types of W.FL cables
The following cables enable antennas to be connected via the larger RP-SMA or SMA connectors. The SMA connector is used for cellular, LPWAN, and GPS networking, while the RP-SMA connector is predominantly used for Wi-Fi.
- W.FL to RP-SMA-female
- W.FL to SMA-male
- W.FL to SMA-female
W.FL connector vs U.FL connector
W.FL connectors are similar to the U.FL connector, but larger U.FL connectors mount on area of 7.7mm and weigh 15.7 mg. With both connectors, the mated height varies depending on the diameter of the coaxial cable used; W.FL ranges between 1.55mm–1.85mm, and the U.FL’s between 2mm - 2.50mm. Due to their complexity and size, these connectors have a limited mating cycle. W.FL has a maximum mating cycle of 20, and the U.FL has a maximum mating cycle of 30 times.
Applications of the W.FL Connector
With wireless devices progressively getting smaller, W.FL connectors have a wide range of applications because of their small size, low weight, and reliability at high frequencies. You will find them being used in devices that are handheld and mobile. Here is a list of common applications of W.FL connectors and cables.
- Antenna connector for Bluetooth devices
- Data terminals
- Digital cameras
- GPS devices
- As the jack of mini-PCI Wireless cards
- Wi-Fi access points and router
- IOT wireless instruments including sensors and actuators
The W.FL connector exceeds the more common U.FL connector in compactness and low weight. You can use it in a wide range of electronic applications where space is extremely limited.