There are no plans right now for a 75 Ω VNA. However, the PicoVNA 106 and software do support 75 Ω measurement, either:
If you are working with 75 Ω systems you may already have a suitable port impedance adaptor and cal kit.
Time domain network analysis and frequency domain network analysis are very similar measurements. The former applies a spectrum of discrete frequencies to the unknown network: a step or impulse incident waveform is applied and an oscilloscope or sampling head captures the reflected and transmitted waveforms. The latter applies a series of discrete frequencies and captures reflected and transmitted amplitude and phase using phase-sensitive (IQ) receivers.
The frequency domain VNA approach has better dynamic range because the applied power at each frequency can be constant and relatively high, and the receivers can have restricted noise bandwidth.
TDR/TDT can theoretically be quicker because a single step or impulse could give all necessary information. However, the high sampling-time resolution required by this method tends to call for a sequential sampling oscilloscope such as the PicoScope 9311. This captures only one sample point on each cycle of a step or impulse, so only repeating signals can be tested. Even so, our TDR or TDT solution is still slightly quicker than the VNA. See below regarding multiple forward, reverse, transmission and reflection measurements.
Not at present, but we would be interested to know your requirements.
The SMA and PC3.5 connectors on the PicoVNA 106 make ideal relatively low-uncertainty ports from which to port-adapt both to the larger format and legacy interfaces and to the emerging smaller format and point-contact interfaces. In many cases, port adaptors can achieve sufficiently low measurement uncertainty for systems with connector types of poorer repeatability, and in other applications where performance is not limited by the connector.
Where measurement demands are high, you may be able to obtain port adaptors with either de-embed data or reference plane offset values; both these correction mechanisms being supported by the PicoVNA 106. In the absence of data, you can purchase a mating pair of port adapters such as PC3.5(f/m) to N(m) and PC3.5(f/m) to N(f). Mate the pair at the N-ports and measure them, then attribute half of the transmission parameters and an average of the reflection parameters to each. This is often how the manufacturer measures adaptors that are provided with data.
Ideally, the adapted ports would be calibrated with port-matching cal kits. These are available from a range of suppliers.
Likewise, within-series and adapting test leads are even more widely available than cal kits. However, it seems likely that emerging small-format connectors will demand a lighter-gauge, more flexible test lead or a flexible port adaptor. Please let us know if you have special requirements in this area.
No, it does not.
In most circumstances a vector network analyzer stimulates a device port in signal frequency steps and measures all the ports at the same frequency steps. However, there are applications where you need to measure at harmonics of the stimulus. There are also applications, around frequency mixer devices, where you need to measure at a frequency (the intermediate frequency, or IF) that is offset from the stimulus. This requires more hardware capability than is present in the PicoVNA 106 and thus is not supported.
From the specification we have:
Be careful when comparing with competitors, as they tend only to quote figures for the single-point single sweep. That compares with our faster figure above and not with the slightly longer time for a forward and reverse sweep necessary for a full set of S-parameters. This product is amongst the faster units available. See the competitive comparison on the web site under the Reviews tab.
The sweep speed reduces according to bandwidth settings as the measurement at the output of bandwidth filter has to settle to its full accuracy.
If we first set a 10,001 pt sweep, the forward/reverse switch is proportionally less of an interruption and we can estimate its duration from the two trace lengths that we have.
At 140 kHz 170 us / pt for full s2p (two sweeps):
Testing at other bandwidths for 10k point sweeps: