Vector Network-Analyzer for 130 - 150 GHz

A vector network-analyzer is described, which is in use for waveguide component tests over the 130 - 150 GHz frequency range. The set up consists mainly of standard laboratory equipment, only a few components are custom designed for the 2 mm wavelength range. Measurement examples are given. The operation principle may briefly be described as follows: A test signal f
₁
+f
₂
is generated by mixing a LO signal with f
_l
≈ 15 GHz and an auxiliary signal with f
₂
= 200 MHz. At the mixer output the LO signal and the lower sideband are suppressed. The upper sideband is multiplied by nine (n=9). Having passed the device under test, it is down converted by a harmonic mixer. The resulting IF-level and phase shift are measured at n·200 MHz = 1.8 GHz with the vector-voltmeter. The multiplied test signal and the local oscillator signal of the harmonic mixer are derived from the same signal source. Swept measurements are performed by tuning the LO frequency. The same principle can be used in a wide range of waveguide-bands.