SMP Connectors

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A GPO "bullet" you might find on Ebay

SMP connectors are miniature push-on connectors, originally marketed by the Gilbert company (now Corning Gilbert) during the 1980's under the trade name GPO, which signifies "Gilbert push-on". Subsequent versions of the connector include GPPO, G3PO, and G4PO, all of which are trademarks belonging to Corning. Other connector companies have compatible versions of these connectors under the generic "SMP" terminology, or may have their own trade names.

The SMP-style push-on connector interface typically has an inner female-to-female component, called a bullet or blindmate, and two outer panel, circuit or cable-mounted receptacles called shrouds. The whole system lets you make connections without threads at all, so you don't need any tiny wrenches. The best part about this system is that a small amount of radial misalignment is possible during mating, something that would be unacceptable with threaded connectors. For example, you might use three such connections between an antenna/feed/monopulse network and a Ka-band transceiver module (perhaps some readers might know of such a system!) However, no one should assume this capability is "free", you will surely suffer a few tenths of a dB in insertion and mismatch losses, especially at millimeterwave frequencies.

SMP connectors are covered by MIL-STD 348, 326-1 thru -5. The smaller SMPM version is covered by MIL-STD-348; 328-1 thru -3. This document merely defines the mechanical dimensions of connectors and does not attempt to assign RF performance targets. Thanks to Ruth at Emerson for clearing that up!

SMP is believed to stand for "sub-miniature push-on". Therefore, (we believe) SMP-M stands for "subminiature push-on, micro", and SMPS stands for "subminiature push-on, sub-micro".

We borrowed the two marketing images below from Corning Gilbert, hopefully they don't mind the free advertising... These two photos will give you a sense of just how small the SMP series can get.

G3PO bullets

G4PO bullets

Frequency ranges of SMP

It is odd that the G4PO does is not rated to 110 GHz, as it surely is small enough to pass W-band signals without spurious modes.

Detent

Push-on connectors are easier than other types of connectors to put on and take off, but you have to be careful because you don't want them coming off accidentally. The amount of force you need to connect or disconnect SMP push-on connectors is called "detent" (say "dee-tent" with equal emphasis on each syllable). More than one engineer has said or spelled "detente" when they meant to say detent. Detente is French for "relaxation" and is pronounced "day-TANTE" (where tante rhymes with font) and refers to a political situation, get that straight!

You can get SMP connectors with various levels of detent, as described in this table:

If anyone has more information on SMP please email us!