VNA Extends Four-Port Measurements to 50 GHz

Yassen Mikhailov
Product Manager, Network Analyzers
Rohde & Schwarz, 8661A Robert Fulton Dr.,
Columbia, MD 21046-2265; (410) 910-7800, FAX: (410) 910-7801, e-mail:, Internet:

This instrument brings high performance and four independent test ports to frequencies as high as 50 GHz for component and device S-parameter measurements. Vector network analyzers (VNAs) with four ports (instead of two) help improve multiport device testing speed and accuracy by cutting down on the number of necessary connections between test system and device under test (DUT). The R&S ZVA50 VNA from Rohde & Schwarz brings fourport capability to 50 GHz for the first time in the manufacturer's VNA lineup, joining earlier four-port models with coverage to 8, 24, and 40 GHz.

Keeping up the hardware concept of all R&S ZVA, ZVB, and ZVT network analyzers with one independent internal source per pair of test ports, R&S ZVA50 4-port incorporates two sources. This makes measurements like mixer testing, two-tone-intermodulation evaluation of amplifiers, or even true differential stimulation of balanced devices convenient to setup. Two independent sources provide seamless integration of R&S frequency converters for measurements to 110 GHz.

The R&S ZVA50 has a full frequency range of 10 MHz to 50 GHz with 1-Hz frequency resolution. It achieves a dynamic range of better than 110 dB at 50 GHz (typically better than 135 dB at lower frequencies), with more than +6 dBm test port power at 50 GHz (typically +18 dBm at lower frequencies) and -95 dBm noise at 50 GHz (and -115 dBm at lower frequencies).

The R&S ZVA50 VNA (see figure) is designed for high-throughput testing, with measurement time per point of less than 3.5 s and measurement speed (for 201 points) of less than 4.5 ms. In an automatic-test-equipment (ATE) environment, the VNA requires less than 0.7 ms to move 201 points of measurement data across a 100-Mb/s Ethernet connection.

The R&S ZVA50 four-port VNA supports a wide range of calibration methods, including seven-term techniques such as though-reflect-line (TRL), line-reflect-line (LRL), through-openmatch (TOM), and through-reflectmatch (TRM) techniques. It also allows the use of a through connection with unknown parameters to be used with open, short, and match standards in a UOSM calibration approach so that any adapter can be used as through.

As with the lower-frequency fourport models, the R&S ZVA50 VNA provides a familiar user interface, based on the Windows XP Embedded operating system. The analyzer provides 10/100 Ethernet and IEEE-488 (GPIB) interfaces, four Universal Serial Bus (USB) ports, and optional automated multiport calibration. Test results are shown on a 10.4-in. thin-film-transistor (TFT) liquid-crystal-display (LCD) screen.

The R&S ZVA50 is available with a measurement option for pulse profile measurements, with pulses as short as 100 ns and with 12.5-ns resolution. The analyzer is also available with optional R&S "true differential" measurement capability for analyzing balanced devices and components. The company's R&S NRP series of power sensors can be connected to the R&S ZVA50 via USB port to add precision power measurement capability. Rohde & Schwarz, 8661A Robert Fulton Dr., Columbia, MD 21046-2265; (410) 910-7800, FAX: (410) 910-7801, e-mail:, Internet: