AnnaLyza VNA


AnnaLyza VNA is a low-cost USB-based 2-port Vector Network Analyzer / Antenna Analyzer for the 2.4 GHz ISM band. The frequency range is 2200 to 2700 MHz.

The software requires Java 8 or later and has been tested under Windows 7 and 10. It has been reported to work under MacOS 10.12 and Ubuntu 18.04. You can test drive the software in a demo mode without the device to explore most functionality. The matching circuit editor is quite useful even in demo mode.

Specifications - ALV2227A2

Frequency Range2200 MHz to 2700 MHz
Impedance50 Ohms
Output Power-18 dBm to -3 dBm (-7 dBm typical)
Input PowerUp to 0 dBm (+10 dBm absolute maximum)
Port Count2
Port Isolation45 dB
Noise Floor-40 to -60 dB 1
RF Connector2x SMA
Data ConnectorMini USB
Supply Current300mA max
Dimensions115mm x 75mm x 30mm (4½" x 3" x 1¼")
Mass90 grams (3.2 oz)
Operating Temperature15°C to 25°C (60°F to 77°F) 2

1 This device only has a single receiver, so measurements with the same output port can affect each other's accuracy (S11 affects S21 and vice versa; S22 affects S12 and vice versa). The error and noise levels are typically 40 dB below the input power on the opposite port, with a lower limit of -60 dB.

2 The receiver is temperature stabilized when the device is operated in this range. The device will work from 5°C to 40°C (40°F to 105°F); however, the accuracy will be reduced. Depending on the ambient temperature the warm-up time is between 20 and 60 seconds.

Software Features

This is the initial release. More features are on the way.

Limitations of the current software version:

Examples and Accuracy

This section shows some measurement examples to illustrate what kind of accuracy to expect. The errors largely result from uncompensated non-linearities in the VNA's receiver and cross-talk between signals in the VNA which are not captured by the error model.

Errors are going to be worse the further away the measurement is from a calibration point (short, open, 50 Ohms). Therefore, the worst errors can be observed on the top and bottom of the Smith chart.

For the figures below I performed a full two-port calibration with the following cables: 2 meter coax cable with approximately 2 dB loss on port 1; 0.4 meter coax cable with approximately 0.8 dB loss on port 2.

The first example is an S11 and S22 measurement with open circuit with a shorter length (calibration standards removed from the coax cables). The traces are near the top of the Smith chart, so they are at a point where the error is at a maximum.

Measurement Example 1: Region with worst accuracy. Click for full-size image.

The next example is another open circuit, this time longer than in the calibration setup (SMA M/F and F/M adapters added).

Measurement Example 2: Open circuit with different length. Click for full-size image.

The next example is with unterminated attenuators attached to the end of the cables. S11 is with a 2dB attenuator; S22 is with a 6dB attenuator.

Measurement Example 3: Unterminated attenuators. Click for full-size image.

The next example shows through measurements (S21, S12) with 2dB attenuator.

Measurement Example 4: 2dB attenuator. Click for full-size image.

The next example shows through measurements (S21, S12) with 30dB attenuator.

Measurement Example 5: 30dB attenuator. Click for full-size image.

The next example shows all four S-parameters with two types of antennas connected.

Measurement Example 6: Antennas. Click for full-size image.