This test system is designed to test the conversion loss of OML harmonic mixers up to 110 GHz.   The primary measurement device and the controller in the system is an Anritsu 37xxx vector network analyzer (VNA) operating as a single frequency (I.F.) calibrated power measurement receiver.   The system R.F. and L.O synthesizers are Anritsu 68xxx microwave synthesizers.   An Anritsu 6709B synthesizer is used as the calibration source and system power reference.  An Agilent/HP power meter is used for calibrating the various sources.   The L.O./I.F. diplexer, I.F. amplifier, and the bias supply have been assembled as a single unit by OML to ensure proper control of those functions.   The entire system is made coherent through the use of a common 10 MHz reference signal.

Files containing all of the R.F. and L.O. synthesizer and VNA setup information for each waveguide band for each spectrum analyzer type are maintained on the VNA hard drive.   A file will include the R.F. frequency (including multiplier if needed), the L.O. frequency, multiplier and offset, and the I.F. frequency as well as power settings and all graphic display information for a given spectrum analyzer and waveguide band emulation.

The calibration source is set to -30 dBm (may change from setup to setup).   All three signal sources are then measured with a calibrated power meter using the appropriate power sensor.   The level of each signal source then receives any necessary adjustment to the level specified for that particular setup to ensure the accuracy of the measurement.

The calibration source is set to the mixer I.F. and its output power is split, with equal power P(c) going to the VNA A1 (reference port) and the diplexer input (Z) to calibrate the OML I.F. chain.   The calibration signal power P(c) is set to the same level as the R.F. power P(rf) being applied to the mixer, typically -30 dBm.   The VNA is set to display B1/A1, the ratio of the two equal calibration signal paths which is then put into memory to normalize the measurement.   The mixer interconnect cable is then connected to the diplexer.