1166 IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT, VOL. 57, NO. 6,JUNE 2008 Two-Port Vector Network Analyzer Measurements Up to 508 GHz Andy Fung, Member, IEEE, Lorene Samoska, Senior Member, IEEE, Goutam Chattopadhyay, Senior Member, IEEE, Todd Gaier, Pekka Kangaslahti, Member, IEEE, David Pukala, Charles Oleson, Member, IEEE, Anthony Denning, and Yuenie Lau, Member, IEEE Abstract—We present new results for a two-port vector network analyzer swept-frequency test set for the 325–508 GHz frequency band. The calibrated dynamic range performance in the full frequency band is discussed. Using a line–reflect–line calibration procedure, the dynamic ranges for return and insertion losses of better than −20 and −35 dB, respectively, are achieved. We examine the performance of the calibrated test set for the first time by measuring S-parameters of passive waveguide components and comparing data with electromagnetic simulations. Index Terms—Measurement, millimeter-wave measurements, monolithic microwave integrated circuit (MMIC) amplifiers, MMICs, scattering parameter measurement, submillimeter-wave amplifiers, submillimeter-wave circuits, submillimeter-wave mea- surements, submillimeter-wave technology, submillimeter-wave transistors, submillimeter-wave waveguides. I. I NTRODUCTION E FFORTS to extend vector network measurements to higher frequencies are motivated by the need to charac- terize advanced microwave devices that perform beyond the frequency band of conventional test systems. By measuring S-parameters of such devices, designs and models can be verified, and utilization of such devices can be optimized. The first swept-frequency full two-port on-wafer vector network analyzer (VNA) measurement test set of up to 220 GHz was reported in 1999 [1], and that of up to 325 GHz was reported in 2005 [2], [3]. Subsequently, extension of on- wafer and waveguide tests to approximately 340 GHz has been demonstrated [3]–[5]. Limited initial calibrated dynamic range results in the 356–500 GHz band have been introduced [5]. In this paper, we present new results in the calibrated dynamic range for the full 325–508 GHz frequency band. In addition, we present the first measurements with the calibrated test set of passive waveguide components and compare the results with Ansoft HFSS electromagnetic (EM) wave simulations. Cur- rently, WR3 (inside waveguide dimensions of 0.034 × 0.017 in and waveguide band of 220–325 GHz) waveguide components are commercially available, and WR2.2 (inside waveguide Manuscript received March 2, 2007; revised October 4, 2007. This work was supported in part by the National Aeronautics and Space Administration, by the Defense Advanced Research Projects Agency under the Submillimeter Wave Imaging Focal-plane Technology (SWIFT) Program, and by the Army Research Laboratory under Contract W911QX-06-C-0050. A. Fung, L. Samoska, G. Chattopadhyay, T. Gaier, P. Kangaslahti, and D. Pukala are with the Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 USA (e-mail: andy.k.fung@jpl.nasa.gov). C. Oleson, A. Denning, and Y. Lau are with Oleson Microwave Laboratories, Inc., Morgan Hill, CA 95037 USA. Digital Object Identifier 10.1109/TIM.2007.915125 dimensions of 0.022 × 0.011 in and waveguide band of 325– 500 GHz) components are being developed. Recent progress in 35-nm gate length InP high-electron mobility transistors (HEMTs) at Northrop Grumman Corp. [6] has produced three-stage amplifiers with 11.6-dB peak S21 gain at 270 GHz (with gain out to at least 340 GHz) [4] and noise figure of 7.5 dB at 270 GHz [7]. Oscillators that utilize the same HEMT technology have shown fundamental peaks at 254, 314, and 346 GHz with 158, 46, and 25 µW measured output power, respectively [8]. Advances in these devices benefit elec- tronics for communications, millimeter-wave imaging systems, and radiometers for earth remote sensing and astrophysics [9]. VNA measurement capability of these components in the 325–500 GHz band will be critical for the advancement of these applications. II. WR2.2 TEST SET DESCRIPTION AND CALIBRATION The WR2.2 test set consists of an Agilent 50-GHz VNA S-parameter system [5] and newly developed Oleson Micro- wave Laboratories (OML), Inc., V02.2VNA2-T/R frequency extenders (see Fig. 1) [10]. To extend the 50-GHz test set to the WR2.2 frequency band, the frequency extenders are interfaced with the 50-GHz VNA S-parameter system using attenuators and amplifiers to adjust power levels of RF and IF signals between the hardware. One frequency extension module is required per VNA S-parameter port. For the WR2.2 test set, harmonic multipliers of 30 and 28 are used for RF and local oscillator (LO) inputs, respectively, to reach 325–508 GHz. The V02.2VNA2-T/R frequency extender module operates on four signal chains between it and the 50-GHz test set. They are the RF input, LO input, reference IF output, and test IF output chains. The RF input chain consists of an isolator to improve the match between the input connector/cable and the doubler/ amplifier module. The doubler/amplifier drives a ×15 multi- plier chain, which produces approximately −30 dBm at the output of the dual directional coupler for the WR2.2 frequency band VNA port. The LO input chain also uses an input isolator to reduce sig- nal fluctuations due to connector/cable mismatches to another doubler/amplifier. The doubler/amplifier output is equally split to drive two subsequent doublers. The resulting WR15 power level is 10 dBm or more and provides the necessary LO power to drive the seventh harmonic mixers to downconvert the test and reference signals of the WR2.2 VNA port. 0018-9456/$25.00 © 2008 IEEE