I have a 'Mifi'™ 4G modem. I ordered an external aerial for it, but the diameter of the connector is about four times the size I need. I want to buy an adaptor, but I don't know what search terms to use.

What are the names of these types of coax connectors, both on the cable and the modem? Is there a common name for the adaptor?

Modem and aerial

The coin, for size reference, is a US 'dime' (10c) and has a diameter of 18mm.

  • \$\begingroup\$ Coincidently a long time ago designers had to use reverse polization connectors and what not to keep people from adding their own unapproved antennas but RP became too common place. It appears they found a solution... \$\endgroup\$
    – Bageletas
    Oct 1, 2017 at 19:27
  • \$\begingroup\$ Show the antenna jack \$\endgroup\$ Oct 1, 2017 at 19:27

2 Answers 2


If you want to replace your tiny antenna with the big one, the part with the outer thread nut is the Male connector and it normally has a center pin unless it is Reverse Polarity RP.

Match this up to your required connections. It is best to use the big coax with Type N for lowest loss on long cables and then small adapters at the modem.

Here is an example of type N female to SMA Male adapter worth about $5 or more.

enter image description here

Looks like an SMA connector with an 8mm hex nut which has a defined torque spec.

Sounds like you got a Type N connector.

To be more precise it is an SMA Male plug that you show and not a reverse polarity RP-SMA Male plug. enter image description here

  • \$\begingroup\$ Good to know—thanks. Any idea about the connector on the modem? \$\endgroup\$ Oct 1, 2017 at 18:55
  • \$\begingroup\$ Might be QMA connector... \$\endgroup\$
    – vidarlo
    Oct 1, 2017 at 19:02
  • \$\begingroup\$ might be mmcx or mcx; you should make an actual outer diameter measurement with calipers. \$\endgroup\$ Oct 1, 2017 at 19:04
  • \$\begingroup\$ definitely not QMA, MMCX or MCX . SMA has no split contacts, just threads. \$\endgroup\$ Oct 1, 2017 at 19:07
  • \$\begingroup\$ @TonyStewart.EEsince'75 how are you ruling out MMCX/MCX on the modem side (not the antenna side, at which I 100% agree with you)? \$\endgroup\$ Oct 1, 2017 at 19:24

The antenna connector in the MiFi 4G modem is a TS9 connector.


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