Overview

U.FL and MHF4 antenna cables are widely used in compact RF applications where space is limited, such as:

• IoT devices
• Mini PCI / M.2 wireless cards
• Cellular modems (LTE / 5G)
• WiFi and Bluetooth modules

These micro-coax cable assemblies are critical for maintaining reliable RF performance while fitting into tight enclosures. One of the most important considerations when selecting these cables is coaxial cable thickness, as it directly affects:

• Signal loss (attenuation)
• Flexibility
• Mechanical stability
• Connector retention

At Data Alliance, we offer a range of U.FL cable assemblies and adapters designed for low loss, durability, and compatibility with real-world installations.

Coax Types for U.FL and MHF4 Cables

There are four primary coaxial cable types used in U.FL cable assemblies:

• 1.13 mm mini coax
• 1.32 mm mini coax
• 1.37 mm mini coax
• RG-174 equivalent coax

A less common option is:

• RG-178 coax

Key Common Characteristics

All of these cable types share the following:

• 50 Ohm impedance (standard for RF systems)
• Compatible with frequencies up to 6–11 GHz (and often higher depending on design)
• Black outer jacket
• RoHS and REACH compliant

Suitable for WiFi, cellular, and IoT applications

Important Limitation: MHF4 Cable Compatibility

MHF4 connectors are extremely small and can only be used with 1.13 mm coaxial cable.

• Not compatible with RG-174
• Not compatible with LMR-type cables
• Not compatible with thicker mini-coax

This is a key constraint when designing or selecting cables for compact LTE or 5G modules.

Detailed Comparison of Cable Types

1. 1.13 mm Mini-Coax (Ultra-Thin)

This is the most common cable used with U.FL and MHF4 connectors.

Advantages:

• Extremely thin and flexible
• Ideal for tight internal spaces
• Prevents stress on delicate U.FL connectors
• Required for MHF4

Use Cases:

• Inside enclosures
• MiniPCI / M.2 cards
• Embedded IoT devices

Important Note (Tech Support Insight):
In tight installations, thicker cables can cause the U.FL connector to pop off the PCB jack. In these cases, 1.13 mm cable is not optional—it is required.

Tradeoff:

• Higher signal loss compared to thicker cables

2. 1.32 mm Mini-Coax (Balanced Option)

This cable provides a balance between flexibility and performance.

Advantages:

• Lower signal loss than 1.13 mm
• Still relatively thin and flexible
• Often double-shielded

Use Cases:

• Medium-length internal runs
• Applications where slightly better RF performance is needed

3. 1.37 mm Mini-Coax

Less commonly specified, but similar to 1.32 mm:

• Slightly thicker
• Slightly lower loss
• Moderate flexibility

Used in specialized applications where a balance of performance and size is required.

4. RG-174 Equivalent (Best Performance for U.FL)

This is the thickest and lowest-loss option available for U.FL cables.

Advantages:

• Significantly lower signal loss
• Excellent shielding (braided + dielectric layers)
• Better performance for longer cable runs

Limitations:

• Too thick for MHF4
• May cause mechanical stress on U.FL connectors
• Not suitable for very tight spaces

Best Practice (Data Alliance Recommendation):

If space allows and connector retention can be secured, RG-174 is the preferred option for performance.

Cable Selection Guidelines (Real-World)

Choose 1.13 mm when:

• Space is extremely tight
• Using MHF4 connectors
• Cable length is short
• Connector retention is critical

Choose 1.32 / 1.37 mm when:

• You need better performance than 1.13 mm
• Space is limited but not extremely tight
• Moderate cable length

Choose RG-174 when:

• Cable length is longer
• Signal loss must be minimized
• Installation allows for thicker cable

You can secure the connector

Practical Installation Tip (Highly Recommended)

If using thicker coax like RG-174 with U.FL:

• Use hot glue or mechanical strain relief at the PCB
• This prevents connector detachment
• Greatly improves long-term reliability

This is a common field solution used by installers and integrators.

For applications requiring a U.FL connection to devices with antenna jacks using SMA Connector or RP-SMA Connector, antenna cable adapters are a convenient solution. Cables like RP-SMA to U.FL or SMA to U.FL provide compatibility between different connector types.

MHF4 cables, and W.FL cables cables can only be made with the very thin coax 1.13mm.   MHF4 is not compatible with LMR100 and RG178.

1.13, 132, and RG174 coaxial cables: All three have a central, plastic insulated wire to conduct the RF signal, further surrounded by a braided mesh, shielding the conducting wire from electromagnetic interference. This conducting shield is covered by an outer insulating layer. The design provides extremely efficient data transmission and where appropriately connected to an antenna the RF signal can be transmitted with minimal signal loss.

1.13, 132, and RG174 coaxial cables range of frequency band compatibility (from 0 to 18GHz) and 50 Ohms impedance matching, makes them suitable and compliant for all the following applications:

• All WiFi standards: 2.4GHz and 5GHz applications: 802.11AC, 802.11N, 802.11G, 802.11B, 802.11A
• Cellular Wireless LTE / 4G, GSM / 3GWiMax: Data and voice applications
• IoT wireless & Bluetooth, ZigBee, RFID, LoRa, LTE-m, NB-IoT.

RF Performance & Attenuation

Signal loss increases with frequency and decreases with thicker cable.

Example: 1.13 mm Cable Attenuation

Key Insight:

• At higher frequencies (WiFi 5 GHz, LTE, 5G), cable loss becomes significant
• This is why short cable length and proper cable selection are critical

See list of all of our articles about U.FL cables and connectors.

Cable Construction (Why It Matters)

All these coaxial cables share a similar structure:

• Central conductor (signal path)
• Dielectric insulation
• Shielding (braid or foil)
• Outer jacket

Higher-quality shielding (as in RG-174) results in:

• Lower signal loss
• Better EMI protection
• Improved overall RF performance

Supported Applications

These cable types are compatible with a wide range of wireless technologies:

WiFi

• 2.4 GHz and 5 GHz
• 802.11a/b/g/n/ac

Cellular

• LTE / 4G / 5G
• GSM / 3G

IoT & Short-Range Wireless

• Bluetooth
• ZigBee
• LoRa
• NB-IoT

• RFID

Connector Types & Adapter Solutions

U.FL cables are often used to interface with external antennas via adapters:

• U.FL to SMA
• U.FL to RP-SMA
• MHF4 to SMA
• MHF4 to RP-SMA

These adapters allow integration with:

• External antennas
• Enclosures
• Panel-mount connectors

Data Alliance Focus:
We provide a wide range of adapter cables and custom assemblies to ensure compatibility across devices and antenna systems.

Important Connector Note

If your PCB has a U.FL jack:

• The cable connector is typically referred to as U.FL plug (male)
• The PCB connector is the mating interface

Correct terminology is important when ordering or troubleshooting.

Micro-Connector Considerations

U.FL and MHF4 connectors are:

• Designed for limited mating cycles
• Sensitive to improper installation

Best Practices:

• Always align carefully before pressing
• Avoid pulling on the cable

Use proper tools when possible

U.FL to SMA Cable diagram

If there is a U.FL jack on your PCB, it is a U.FL male.

Data Alliance Engineering Recommendations

From a real-world deployment perspective:

• Keep cables as short as possible
• Avoid sharp bends
• Use low-loss cable for longer runs
• Ensure secure connections
• Match connector types carefully

For custom applications, Data Alliance can provide:

• Custom cable lengths
• Specific connector combinations
• Optimized coax selection

Conclusion

U.FL and MHF4 antenna cables are essential components in modern wireless systems where space, performance, and reliability must be carefully balanced.

Key takeaways:

• 1.13 mm = best for tight spaces and MHF4
• 1.32 / 1.37 mm = balanced performance and flexibility
• RG-174 = best RF performance for U.FL (if space allows)
• Cable selection directly impacts signal quality and system reliability

By selecting the correct coax type and following best practices, you can ensure optimal RF performance across WiFi, cellular, and IoT applications.

Quick Summary

• MHF4 cables require 1.13 mm coax
• U.FL cables support multiple coax types
• Thicker cable = lower signal loss
• Thinner cable = better flexibility and fit

Always balance performance vs space constraints