RF Switches

RF switches are devices that route radio frequency signals to particular waveguides.  Important performance specifications to consider when searching for RF switches include the frequency range, insertion loss, isolation, switching speed, impedance, and VSWR.  The frequency range is the signal frequency range of the switch.  Insertion loss is the total RF power transmission loss resulting from the insertion of a device in a transmission line. It is defined as the ratio of signal power at the output of the inserted device to the input signal power at the input of the inserted device.  The isolation from port A to port B of a device is defined as the degree of attenuation of the signal at port A measured at the B port with all other ports properly terminated.  Isolation is expressed in dB.  The switching speed is the speed at which the switch can operate.  Impedance is typically either 50 ohms or 75 ohms.  When there are impedance mismatches in a system, some energy transmitted through will be reflected back to the source. Different amounts of energy will be reflected back depending on the frequency of the signal.   VSWR (Voltage Standing Wave Ratio) is a unitless ratio ranging from 1 to infinity, expressing the amount of reflected energy.  A value of one indicates that all the energy will pass through, while any other value indicates that a portion of the energy will be reflected.

The switch actuator for RF switches can be single pole single throw (SPST), single pole double throw (SPDT), double pole single throw (DPST), double pole double throw (DPDT), single pole four throw (SP4T), single pole eight throw (SP8T), and single pole twelve throw (SP12T).  Actuator voltage is also an important to consider.  Common control interface choices for RF switches include RJ-45, RS232, RS422, and TTL.  Package types for RF switches include surface mount, flatpack, through hole or plug-in, connectorized, and waveguide assembly.  In Surface Mount Technology (SMT), components are mounted on printed circuit boards by soldering the component leads or terminals to the top surface of the board.  A flatpack is an IC package with gull wing or flat leads on two or four sides.  In Through Hole Technology (THT), components are mounted on printed circuit boards by inserting component leads through holes in the board and then soldering.  A connectorized package is a component that is attached to the system by mean of connectors such as coaxial or other type.  A waveguide assembly is a unit that is used in a microwave waveguide system. A waveguide normally consists of a hollow metallic conductor, usually rectangular, elliptical, or circular in cross-section. Under certain conditions it may contain a solid or gaseous dielectric material.  Common features for RF modules include connector type choices, antenna connector, LED indicators, adjustable power output, and environmental parameters.  Choices for connector types include BNC, MCX, Mini UHF, MMCX, SMA, SMB, SMP, TNC, Type F, Type N, UHF, 1.6 / 5.6, and 7/16.  An important environmental parameter to consider is the operating temperature.

• Low Distortion PIN Diode Switch Using Surface Mount Devices - App Note
  One of the practical applications of the surface mounted PIN diode is in the design of low current, low cost RF switches. In the design of such circuits, the diode is generally treated as a current...
  (read more)
• Low Cost Switched Diversity System (.pdf)
  This paper presents a low-cost switched diversity receiver system utilizing a single tuner, simple remote antenna unit and one RF cable. The switched diversity algorithm is implemented in the receiver...
  (read more)
• Comparison of Bulk and Epitaxial PIN Diodes in Low-Cost Wideband RF Switching - White Paper
  Both electromechanical and semiconductor switches are proven technologies used in the control and routing of RF signals. While the use of mechanical switches can be justified in precision test...
  (read more)

Pages: 1 - 3 of 407

Part Numbers for RF Switches