Omni-Spectra 203836-20

The Omni-Spectra 203836-20 is a SMA connectorized non-directional 20 dB coupler with TBD frequency coverage. No data sheets were found in an internet search for this device. Today's test is to confirm the 20 dB coupling factor (and that it is non-directional) and to determine the usable frequency range for the device. Four units are available to be tested. (All SMA connections were inspected and cleaned prior to performing any measurements. Two were found to need cleaning - with all being cleaned per normal pre-test process.)

The coupler has a side mounted SMA-female (SMA-F) jack for the coupled port with a SMA-F on one end of the coupler body and a SMA-male (SMA-M) on the other end of the device.

The test setup below shows a Pluto SDR with 5 dB attenuators on the RX and TX ports, two SMA-M to SMA-M test cables, the 40 dB attenuator calibration set for the SATSAGEN software 40 dB calibration point, a SMA-F to SMA-F adapter used for the through calibration (0 dB), and the four 203836 20 dB couplers to be tested today. After initial test system calibration, the SMA cables are connected to Coupler #1 main-line through to measure the through insertion loss for these units. A SMA termination is applied to the coupled port for this measurement.

The SATSAGEN screen capture below shows the through insertion loss for the couplers is very low (on the order of 0.1 dB) with some measurement system ripple present.

The coaxial cable to the Pluto RX port is moved to the coupled port and the 50 Ohm termination is moved to the through line end of the coupler.

The SATSAGEN screen capture below shows that the coupled port "coupling factor" is close to 20 dB from just under 500 MHz up to the stop frequency of 6 GHz. The ripple in the curve is likely due to the test system (and not the couplers being tested).

To confirm that the coupler works in both directions, a coupled signal level trace was captured and then the cable from the Pluto TX port was moved to the opposite end. The screen capture below shows reasonably similar coupling factors using either end of the through line on the device.

Each of the four couplers were verified to be functional with similar coupling factor curves. The lower frequency coupled-port frequency is just under 500 MHz and the coupler performance was measured to 6 GHz. The upper end is likely to approach 18 GHz given the SMA connectors and physical sizing of this Omni-Spectra component.

All measurements were completed successfully. The four tested 20 dB 500-6000 MHz couplers are available for use in the home laboratory.

How might these be used? Typically they would be used as a signal tap connection point within a microwave system. For example, placing one of these on the output of a signal generator would provide a non-invasive inspection point for the generator's output signal - perhaps as part of a amplitude leveling system. Likely not used everyday, but very helpful when monitoring signals is needed!