Microwave Quick Connect/Disconnect Coaxial Connectors

Maury Microwave Corp.
Ontario, CA

When testing microwave devices it is desirable to have an RF connection that can be made quickly while providing low SWR, high isolation and, most importantly, repeatable measurements. In addition, the connection should be stable and not require external fixturing to ensure repeatability. Various patented quick disconnect coaxial connectors exist today; however, all of these designs employ relatively complex and costly methods for achieving a quick connect/disconnect feature.

A newly designed male slotted connector has been developed, which incorporates a compression ring that provides additional support to the slotted and spread fingers of the outer conductor, resulting in electrically repeatable couplings. The QT3.5mm™ Quick Test male connector (patent pending) is capable of being mated to a female connector and connected and disconnected using just a simple push on/pull off motion. The simplicity and ease of use of this new connector, plus its low manufacturing cost, provide the user with a low cost alternative to the more complex and costly methods currently available.

In addition, the connector may be used with an optional integral coupling nut that allows the option of a threaded coupling when performing calibration or measurement verification tasks. When used, the coupling nut offers an engagement of one-half to one-and-one-half threads, providing the ability to quickly thread or unthread the mating connectors or permitting a standard torque wrench to be used to complete the mating. Another variation of the connector employs a solid outer conductor structure with a compression ring.

The QT3.5mm connector can be used to measure devices that utilize various types or sizes of female connectors, such as SMA, 2.92 mm or 3.5 mm. The female connector of these connector series conventionally mates with a male connector that is screwed on and typically requires five or six full revolutions of the coupling nut to securely mate. This approach is also adaptable to other connector types such as N, TNC, 2.4 mm and other sexed connectors with similar construction.

Table 1
QT3.5 mm Specifications

Frequency range


DC to 26.5 GHz



product dependent


DC to 18 GHz

18 to 26.5 GHz

Push-on mode (dB)



Torque mode (dB)



Hand torqued (dB)



Fig. 1 QT3.5 mm slotted/NMD3.5F connector repeatability;  (a) torqued to 8in/lb, (b) hand-torqued and (c) untorqued. The QT3.5mm Quick Test connectors are supplied in four configurations: the models 8006E1 with no nut, 8006E11 with a 3/8" nut, 8006E21 with a 9/16" nut and 8006Q1 with a guide sleeve. Other models are available that adapt to 7 mm, NMD3.5, N, NMD2.4 and 2.4 mm male and female connectors. Figure 1 shows the repeatability of a QT3.5mm slotted/NMD3.5F connector torqued to 8.5 in/lb, hand-torqued and untorqued. Table 1 lists typical specifications for the QT3.5mm male connector when torqued to 8 in/lb or hand-tightened.

Repeatability and life tests are currently underway. No degradation has been detected thus far after more than 2000 connections. The 2B-060 data sheet (available from the company) describes in detail the connectors and their performance parameters. A simple product demonstration may be arranged by contacting a company representative.

Maury Microwave Corp., Ontario, CA (909) 987-4715.