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I'm currently in the process of redesigning the RF section of a communications system for a cube satellite. There are two PCBs in this system: one containing the down/up converters and modem, and another with the spring loaded dipole antennas, antenna deployment system, LNA, and PA.

The original design used MMCX connectors and two short (~2 inch) runs of RG-316/U (like RG-147/U but made of Teflon and slightly thinner) to connect the TX and RX paths to the LNA and PA, respectively.

My only concern is that MMCX is a push-on connector, which I'm worried might pop out during launch from vibration. Typical pogo oscillations range between 5 and 100 Hz and can be around 1 G both longitudinally and laterally.

I'm probably just being paranoid, but I thought I'd ask in case there's a better alternative. Is there a standard coaxial connector that's similar in size to MCX or MMCX but threaded? My google search isn't turning up anything.

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    \$\begingroup\$ I've probably found my solution - Samtec sells a high-vibration version of the MMCX connector (samtec.com/rf/original/high-vibration.aspx), which is qualified up to 3.8 G random vibration at 5-500 Hz on all axes. I'll leave the question open in case anyone else wants to chime in, though. \$\endgroup\$
    – Synchrondyne
    Commented May 11, 2015 at 2:48
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    \$\begingroup\$ It's always after you make a post on SE that you find the answers, isn't it? Another alternative are SMP connectors, which are still snap-in but are intended for missile use and rated to MIL-STD-202 method 204D, 10Hz-2000Hz at 20 G peak amplitude. They're not cheap (about eight bucks Canadian per connector on DigiKey) but it's not like I need a whole lot of them. \$\endgroup\$
    – Synchrondyne
    Commented May 11, 2015 at 3:15
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    \$\begingroup\$ You should post that as the answer yourself and accept, it saves the question sticking around on the unanswered list. \$\endgroup\$
    – PeterJ
    Commented Sep 30, 2015 at 8:29

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The other option is to simply glue or pot the connector in place. I couldn't speak for space applications, but for military stuff that had shock/vibe requirements we often pot through hole components like big caps and certain connectors to stop them shaking apart.

For an MMCX you could also try solder blobs on the connector body shield down to a ground plane on the PCB.

Failing that, try a different connector more suited to high vibration. Avoid SMPM (GPPO) if you can, the connector locates using the contact pin and has a tendency to deform it with every mate cycle.

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Threaded connectors go as small as you like, mainly for higher frequency work. The down side is the price. Shrinking down from the 2.92mm connector are a number of smaller ones, 2.4mm, 1.85mm and 1mm, but these are quite rare. In reality the only threaded connectors I have seen in satellite gear are SMA and N-type for L or Ku band, 2.92mm for Ka, and F connectors for broadcast.

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    \$\begingroup\$ Those connectors are all physically the same size, the difference is in the bore and center pin. A 1mm connector has a 1mm bore and is good to 110 GHz, but they are incredibly expensive and you get no space savings over using an SMA connector. \$\endgroup\$
    – alex.forencich
    Commented Oct 14, 2015 at 15:57
  • \$\begingroup\$ ah. so not only does my answer not answer the question, it is factually incorrect too. superb. \$\endgroup\$
    – Mark Ch
    Commented Oct 14, 2015 at 20:05

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