here to go to our main page on connectors!
he said, like sex...
A common misconception is that
the sex of a connector has something to do with the outer connector.
WRONG! The sex of the connector refers only to the inner conductor.
With the notable exception of
the "sexless" 7 mm connector, connectors are come in matched
pairs. The term "male" implies a connector where the center
conductor protrudes, while the term "female" implies a
connector where the center connector forms a sleeve around its male
counterpart. Alternative terms are "plug" for male, and
"jack" for female.
Reverse polarity connectors are
ones in which the sex is the opposite of what you'd expect. Reverse
polarity connectors are sometimes used in an attempt to "key"
connections so that incorrect connections are not possible. These
are available from major connector manufacturers as catalog items.
Here's a comment from our message
board about reverse-sex connectors: "FCC rules have led to
a proliferation in the use of reverse sexed RF connectors. For unlicensed
users there is a requirement that the manufacture must ensure that
unauthorized antennas cannot be connected to the equipment. That
is why all WIFI equipment with connectorized antennas use reversed
sex connectors. Cisco uses RP-TNC, Netgear RP-SMA, and Symbol Technologies
RP-BNC for their 802.11b/g (2.4GHz) WIFI radios and access points."
Yikes, we didn't know that these were being proliferated!
In a lab environment, we
recommend that you never use reverse polarity connectors, because it doesn't
prevent connections, any idiot can jam reverse-polarity male connectors
onto normal male connectors and mess them both up. If you want to
make something idiot proof, perhaps you should look at reverse
threads for certain connectors (which are also available from
major connector manufacturers).
In the picture below are three
SSMA connectors. The connector on the left is the normal SSMA male,
while the one on the bottom is the normal female. On the upper right
is a reverse-polarity male connector, it has the normal male pin
inside, but has the external threads of a female connector. If you
look closely, the center pin is bent on the reverse polarity connector;
chances are that the technician that "owns" this connector
doesn't even know it is reverse polarity. Such a connector is useless
if you don't have the opposite reverse-polarity female connector
to mate with it. Jammed into a normal male SSMA male connector,
it probably makes contact, even if the two male pins are bent against
each other (but it won't be a great fifty-ohm match at high frequencies!)
Whenever you find such a connector, put it in a specially-labeled
box, or just throw it out!