MCX, MMCX, AND SMP WHICH ONE SHOULD I USE?
These three push-on connectors are similar and we will discuss the advantages and disadvantages. All of them are 50 Ohm and can mount to both semi rigid and flexible coaxial cables. The size of the connector vary from manufacturer to manufacture; we include typical sizes.
This is the largest of the three connectors with the right angle male measuring typically 0.340 inches (8.63 mm) from the top to the bottom. It comes in right angle male cable mount, PCB mount male and female plus circuit card edge, straight male, straight female, and straight female bulkhead. There is a true 75-Ohm version, which is not compatible with the 50-Ohm version discussed here.
Cost- tends to be the least expensive of the three connectors.
Locking mechanism-It is good, and for most manufacturers will “snap” when positioned. In addition much of the connector body is inserted into the mate giving more robust mechanical attachment. This connector does not decouple easily.
Large center contact- 0.020in (0.508mm) typically. This helps with multiple connects and disconnects. It is 77% larger area than the other center contacts. It is hard to bend a MCX center contact.
Frequency response- limited the connector will perform well to 6 GHz.
Cable choices- can be attached to most small and intermediate cables 0.047 (1.20mm) to 0.2 (5.08mm) OD, which includes the popular RG-316, RG-174, RG-400, RG-142, RG-223, 0.047 and 0.085 semi rigid.
Size- with a larger size the connector, it takes up more space.
Limited Frequency- 6 GHz max.
Locking mechanism is manufacturer specific. Connectors from one manufacturer don’t always mate well with other manufacturers. Some manufactures have as little as 1.0 Lbs (0.45Kg) disengagement force. The typical disengagement force is 2 Lbs (0.9kg).
This connector measuring 0.275 in (7mm) from the top of the connector to the mating surface. The center contact pin is typically 0.016in (4mm) OD.
The MMCX is designed for the smaller cables. 0.047, 0.085 (2.1mm) semi rigid and RG-316, RG-174 (0.10 OD in). The cutoff frequency for the MMCX is usually about 6 GHz.
Size -is the big factor, it is smaller in every aspect to MCX.
Cost- is reasonable 20% more than the MMCX.
Locking mechanism- is not as robust as the MMCX or GPO. The connector will snap in, but it tends to snap out just as easily. The MMCX is better for lab environment. Some manufactures have a minimum disengagement force of 1.4lbs. With that said the MMCX mating surface does not go into the receptacle very deep (unlike the MCX) so it is easy to snap out.
Frequency- limited to 6 GHz.
Cable Choices: Limited to 0.047 to .085 for the semi rigid and 0.1 in OD for the flex cables RG-316, RG-174.
The SMP was designed for the military missile market, where high vibration and high frequency are important. The size is small 0.240in from top of connector to the bottom of the contact. The center contact is 0.015in OD. The frequency range is typically 18GHz with some manufacturers going to 40GHz. Many different flavors of this connector exist, from bulkheads to board mount.
Locking Mechanism: The SMP comes in three flavors: full detent that means it takes about 15 pounds to disengage, partial detent 10 pounds, and smooth bore 2 pounds for disengagement. Good for high vibration environment. The full detent is very difficult to disengage it will not just snap out.
High frequency- performance good to 18-40 GHz depending on manufacturer.
Size- Smallest in size
Military sales guide this connector. Even the commercial connectors are of very high quality since most of the manufacturers sell to the military.
Cost: The SMP can cost three times the MCX.
Cable choices: Limited to 0.047 to .085 for the semi rigid and 0.1 OD for the flex cables RG-316, RG-174.
Center pin- is small so frequent disconnects will damage and bend pins.
WHO MAKES THE BEST CONNECTORS?
The answer is simple-- they all do. What I mean to say is, if you want low cost there is a group of suppliers, if you want performance there is another group. There is no free lunch, one supplier does not offer low cost and high quality. You get what you paid for. One manufacturer uses much thicker gold plating tighter tolerances and their performance is better. Another has wide tolerances and their cost is very low. Select based on your system performance vs. the cost the connector.