This document describes an instrument called the Model 8755 Frequency-Response Measuring System, which can simultaneously measure insertion loss and return loss over a wide frequency range. The instrument features high stability, good repeatability, wide frequency range, and compactness.
The HP 8755A Frequency‑Response Measuring System is a microwave test set that simultaneously displays insertion and return loss over a wide frequency range. It uses three identical Schottky‑barrier diode detectors and a logarithmic amplifier to convert the RF signal to a low‑frequency square‑wave that is displayed on an oscilloscope.
The instrument includes a two‑state absorptive modulator (Model 11665A), a thin‑film hybrid microcircuit for tight dimensional control, and a three‑channel architecture that allows independent measurements and ratio calculations. Specifications include a frequency range to 18 GHz, a dynamic range of 60 dB (‑50 dBm to +10 dBm), 50 Ω detector impedance, and a power requirement of 4‑440 V.
| Frequency range | up to 18 GHz |
|---|---|
| Dynamic range | 60 dB (‑50 dBm to +10 dBm) |
| Power supply | 4‑440 V (118/200 V) |
| Price (U.S.) | $5 200 |
It measures up to 18 GHz.
The detector provides a 60 dB dynamic range from –50 dBm to +10 dBm.
A two‑state absorptive modulator, Model 11665A, is used.
Three identical Schottky‑barrier diode detectors are used.