Guidelines to Follow When Purchasing Connectors for Your RF System Design

Suntsu Small Form Coaxials
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At Suntsu, our focus on wireless communication has helped our customers buy cables focused on antenna-to-board connectivity. As our customers continue to favor smaller and more compact products, we want to ensure you are saving time and money by using the right solution, so which small coaxial RF connector should you use for your antenna cable?

U. FL is the established high-frequency miniature coaxial interconnection type. But it is proprietary to Hirose. Many manufacturers offer 100% U.FL compatible connectors under various names such as IPEX, IPX, MHF, AMC, UMCC, and MCRF.

Is there a difference in U.FL, IPEX, or MMCX (Micro miniature coaxial)? Let us look at a brief comparison of the connector types:

StandardHirose proprietaryDesigned to be U.FL CompatibleCECC 22220
VSWR=<1.30 (Up to 3GHz)
1.30 – 1.50 (3 – 6GHz)
=<1.30 (Up to 3GHz)
1.30 – 1.50 (3 – 6GHz)
=<1.50 (Up to 6GHz)
Size/footprint2.5mm Max mating height
3.0mm diameter plug
2.5mm Max mating height
3.0mm diameter plug
Height varies with jack/
plug combination
2.4mm diameter plug
OrientationRight angle onlyRight angle onlyStraight or right angle
Contact RetentionGood: 0.15N to 4N/
0.03lbs to 0.9lbs
Good: 2N to 4N/
0.45lbs to 0.9lbs
Strong: ? 10N/2.3lbs
Engagement ForceN/A=< 4N/8.6lbs=< 35.6N/8.6lbs
Disengagement ForceN/AInitial: =< 5N /1.12lbs
30 cycles: ? 3N/0.67lbs
6N to 15N/1.4lbs to 3.4lbs
Mating cycles30 cycles30 cycles500 cycles
Removal Tool NeededYesYesNo

At first glance, it appears U.FL/IPEX/IPX have better performance than MMCX because U.FL/IPEX/IPX are designed for lower VSWR at < 3GHz frequencies. However, this is just a surface level comparison. Other factors need to be considered, including performance, robustness, and ease of use across the connector, cable, and endpoint (antenna or otherwise).

When deciding which connector to use, it is crucial to compare performance in an entire antenna/cable assembly. Different combinations of connectors, cable types, and cable lengths will affect system performance, and designers should focus on the VSWR specs of the entire assembly.

Examples of VSWR value (lower is better):
1) IPEX connector: =<1.30
2) MMCX connector: =<1.50
3) SMA connector: =<1.50
4) IPEX to MMCX with 50mm cable: =< 2.00 (whole assembly)
5) MMCX to SMA with 200mm cable: =< 2.00 (whole assembly)

Next, you should examine end-to-end signal paths of antenna and cable assembly. There will be little to no difference in performance between connector types unless the application requires very stringent tolerances. Around 20% of Suntsu’s customers fall into the stringent category, for which we have specialized designs. However, for the other 80%, we recommend a separate set of decision criteria.

For the larger part of our customer base, MMCX will be a better choice. MMCX has much higher contact retention and requires greater force to disengage, meaning it will better withstand jostling and vibration. Because it is designed for 500 mating cycles, MMCX will last longer than U.FL/IPEX/IPX when the connection needs to be disconnected and re-connected regularly.

Ease of Use
Generally, U.FL/IPEX/IPX will work best when space is at a premium in the design, but MMCX will be easier to use from an end user point of view. Take these details into consideration:

• Mating profile: U.FL/IPEX/IPX will have a smaller profile than MMCX – the difference being a 2.5mm maximum height when mated versus 6.0mm minimum height with MMCX.
• Deployability: MMCX offers more configuration options for plug and receptacle, with straight and right-angle options, while U.FL/IPEX/IPX are available only in a straight vertical receptacle and right-angle plug.
• Serviceability: When deployed in the field, U.FL/IPEX/IPX connections require a special tool for extraction, to avoid damage to the connectors. Servicing MMCX connections does not require any special tools.
• Footprint: U.FL/IPEX/IPX and MMCX all have similar footprints of 3 – 4 square mm. Beyond the connector, designers should consider the spacing for the right-angle inserted cables and cable management.

Suntsu has cultivated a select group of suppliers for RF Connector products:

• For common coaxial RF connectors such as BNC, TNC, F-Type, SMA, and SMB, Suntsu offers products from Amtek Technology.
• For standard miniature RF connectors and antennas (SMA, RP-SMA, MMCX, IPX), Suntsu offers products from Master Wave Technology.
• For customers who need customized miniature RF connectors and cable assemblies designed for wireless applications, we offer Suntsu products.

Contact a sales representative if you want suggestions for your RF system design.


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