Radar technology has long been associated with pulsed signals, and generating and analyzing such signals has long been a challenge to those supplying test equipment to architects of different radar systems, whether for military or commercial applications. With the growing use of radar technology in different markets, along with the established use of radar technologies in existing markets, comes the need to test these new radar systems, and Anritsu Co. has responded with its MS4640B series of RF/microwave vector network analyzers (VNAs)—an extension of the firm’s popular VectorStar family of VNAs.

The new analyzers include a host of automatic pulsed measurements, collectively known as the PulseView capabilities, which include pulse profiling, point-in-pulse measurements, and pulse-to-pulse measurements of the S-parameters for active and passive components under test. The analyzers offer measurement capabilities over bandwidths as wide as 70 kHz to 110 GHz from a single coaxial port, while the optional PulseView measurement capabilities can show pulse resolution of 2.5 ns across a dynamic range of 100 dB.

The latest additions to the VectorStar family of VNAs include the MS4640B series instruments, with available optional PulseView pulsed measurements. (The VNAs also offer optional DifferentialView test capabilities, for users grappling with high-speed serial-bus measurements.) An example of the new VNA line is the model MS4647B (Fig. 1), with broad frequency range of 10 MHz to 70 GHz; other members of the VNA family include models MS4642B (10 MHz to 20 GHz), MS4644B (10 MHz to 40 GHz), and MS4645B (10 MHz to 50 GHz).

VNAs Channel Pulsed Measurements, Fig. 1

In terms of their traditional VNA continuous-wave (CW) measurement capabilities, these analyzers offer impressive performance capabilities, with receiver dynamic ranges of 115 dB or better from 2 MHz to 50 GHz and better than 113 dB from 50 to 70 GHz. The receiver 1-dB compression in standard model is +5 dBm through 0.3 MHz and +10 dBm from 0.3 MHz to 70 GHz, with higher compression points available as an option. The VNA noise floors drop to -105 dBm from 2 to 10 MHz and -110 dBm from 10 MHz to 70 GHz, while the available test signal power is +12 to -25 dBm from 10 MHz to 2.5 GHz, +5 to -25 dBm from 2.5 to 50 GHz, and at least -3 to -25 dBm through 70 GHz.

However, these are not just traditional VNAs. When equipped with Option 035 and Option 042 (PulseView™), the MS4640B series VNAs include the capabilities to generate and analyze fast pulsed signals. The pulsed generation/analysis capabilities support 2.5-ns pulse resolution across a 100-dB dynamic range for all frequencies in the MS4640B range through 70 GHz.

Without the options, analyzed signals are frequency downconverted and processed within the intermediate-frequency (IF) section of each VNA. In normal operation, an MS4640B VNA uses an IF with 100-MHz bandwidth and filtering to minimize large image signals. With options 035 and 042, the standard IF system is bypassed and signals are routed to a special high-speed-digitizing IF board with greater than 200-MHz acquisition bandwidth (Figs. 2 and 3). This board consists of analog processing (filtering, gain, calibration, etc.) with the much wider bandwidth than the standard analog IF circuitry, to equip it for measuring very narrow pulses. The digitizing board contains high-speed analog-to-digital converters (ADCs), pulse generators, and digital-signal-processing (DSP) components for pulse generation and analysis. The digitizers enable data acquisition rates to 400 MSamples/s within the VNAs, making possible the 2.5-ns time resolution. Each VNA is supported by deep acquisition memory depths (4 GB) to enable capture of time records of more than 0.5 s with full resolution. The four internal pulse generators are independent of the measurement channels and can be used for RF/microwave stimulus modulation, for modulating bias circuitry, or other applications within a test setup.

VNAs Channel Pulsed Measurements, Fig. 2

VNAs Channel Pulsed Measurements, Fig. 3