Comparing Small Form Factor Coaxial RF Connectors

At Suntsu, one of our focus is in wireless communication. We’ve helped our customers with cables focused on antenna-to-board connectivity. As we mentioned in our prior articles, all of our customers are going compact and smaller. U.FL is the established high frequency miniature coaxial interconnection type. But it is proprietary to Hirose. So many manufacturers offer 100% U.FL compatible connectors under various names such as IPEX, IPX, MHF, AMC, UMCC, and MCRF.

Many of our customers have asked: Which small coaxial RF connector should I use for my antenna cable? Is there a difference in U.FL, IPEX, or MMCX (Micro miniature coaxial)?

Let’s look at a brief comparison of the connector types.  At first glance, it appears U.FL/IPEX/IPX may have better performance than MMCX because U.FL/IPEX/IPX are designed for lower VSWR at < 3GHz frequencies. However, this is just a connector level comparison.  We need to go deeper than just connectors and consider are performance, robustness, and ease of use across the connector, cable and end-point (antenna or otherwise).

Type	U.FL	IPEX/IPX	MMCX
Standard	Hirose proprietary	Designed to be U.FL Compatible	CECC 22220
Manufacturers	Hirose	Many	Many
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/footprint	2.5mm 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
Orientation	Right angle only	Right angle only	Straight or right angle
Contact Retention	Good: 0.15N to 4N/ 0.03lbs to 0.9lbs	Good: 2N to 4N/ 0.45lbs to 0.9lbs	Strong:  ? 10N/2.3lbs
Engagement Force	N/A	=< 4N/8.6lbs	=< 35.6N/8.6lbs
Disengagement Force	N/A	Initial: =< 5N /1.12lbs 30 cycles: ? 3N/0.67lbs	6N to 15N/1.4lbs to 3.4lbs
Mating cycles	30 cycles	30 cycles	500 cycles
Removal Tool Needed	Yes	Yes	No

 

Performance

The table considers just the connector alone.  It is more important 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)

When looking at the end-to-end signal path of antenna and cable assembly, there likely will be little difference in performance between connector types, unless the application requires very stringent tolerances. Around 20% of Nexsun’s customers fall into the stringent category, for which we have done specialized designs.  However, for the other 80%, we consider a different set of decision criteria:

Robustness: 

MMCX is the better choice. MMCX has much higher contact retention than U.FL/IPEX/IPX and requires greater force to disengage, so will better withstand jostling and vibration. Designed for 500 mating cycles, MMCX will last longer than U.FL/IPEX/IPX, if the connection needs to be regularly disconnected and re-connected.

Ease of Use

Generally, U.FL/IPEX/IPX is the better choice when space is at a premium in the design, but MMCX will be easier to use from an end user maintenance point of view.  Here are detailed considerations:

• 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, Suntsu offers Suntsu products.

If you want suggestions for your RF system design, give Suntsu Electronics a call at +1.949.783.7300