ELVA series DC 3-port/4-port directional couplers are available in nine waveguide bands from 26.5 to 220 GHz. The standard coupling levels are 3, 6, 10, 20, 30 and 40 dB with full waveguide operational bandwidth. ELVA directional couplers have directivity of up to 40dB for frequencies below 110GHz and 30dB for upper frequencies.
Directional couplers are in common use for the purpose of transmitting power into a waveguide circuit without perturbing the operating characteristics of the circuit. These couplers are particularly suitable for frequency monitoring and measurement of RF power (transmitted or reflected) in circuits. Directional couplers are used for scalar network analyzers, and for signal sampling in instruments or subsystems.
The directional couplers can be used in different high-frequency equipments. They are used for dividing input signals into multiple output signals with minimum loss of power (forward direction). Some directional couplers can transmit the power forward and back without loss of power. The directional couplers can have 3 or 4 ports. Energy transfer can be done from any port to any directions (it depends on the purpose of the device). The examples are the following:
In practice, the most popular models have 3 ports. In these models there is a terminator on one of the secondary port. The basic function of a 3-port directional coupler is to operate on an input (P1) so that two output signals (P2 and P3) are available. The output signals are unequal in amplitude. The larger signal is at the mainline output port (P2). The smaller signal is at the secondary port (P3).
When the input signal (P1*) is applied to the opposite port of an internally terminated couple (power is transmitted in the back direction) some part of the power are reflected to the opposite direction and it is possible to measure it as P3*. The difference in dB of the output power P3 and P3* is called directivity.
Main characteristics of the directional couplers
Example of product: G-Band Directional Coupler
G-Band Directional Couplers refer to waveguide band from 140 to 220 GHz. These couplers have directivity about 30 dB, insertion loss is maximum 1.5 dB for 140 GHz). G-Band Directional Couplers operate with coupling flatness of less than ± 0.9 dB. The most important parameter of waveguides is VSWR (standing-wave ratio at any port of a coupler when the reflection is terminated at all other ports). For this device VSWR is as low as 1.4:1. For detailed performance report see diagrams below:
How to order ELVA-1 Directional Couplers
Specify Model Number for 3-port Directional Coupler: DC – XX / YY
DC - Directional Coupler
XX – waveguide band (international standard WR-XX)
YY – coupling value (dividing coefficient between main and secondary lines) in dB (3, 6, 10, 20, 30, 40)
Example: To order a Directional Coupler for frequency range 140-220 GHz (standard WR-05) with coupling value 3 dB, please specify DC-05/3.
In case of ordering a nonstandard Directional Coupler, please consult ELVA-1 and provide us your specific parameters.