RigExpert AA-230PRO - Antenna Analyzer (0.3 to 230 MHz) + Time Domain Reflectometer

RigExpert AA-230PRO is a powerful, laboratory grade antenna analyzers designed for testing, checking, tuning or repairing antennas and antenna feedlines in 0.3 to 230 MHz range.

Mainly, these are SWR (Standing Wave Ratio) and impedance measurement instruments (vector impedance analyzers).

Easy-to use measurement modes, as well as additional features such as memory storage and connection to a personal computer, make RigExpert analyzers attractive for professionals and hobbyists. It is quite important that graphical display of various parameters over a wide frequency range is a key feature of these analyzers which significantly reduces the time required to adjust an antenna.

The new MultiSWR and SWR2Air modes are unique for these antenna analyzers. Please refer to SWR Modes tab.

The built-in TDR (Time Domain Reflectometer) mode which is available in RigExpert AA-230PRO is ideal for locating cable faults.

The following tasks are easily accomplished by using RigExpert AA-230:

• Rapid check-out of an antenna
• Tuning an antenna to resonance
• Antenna SWR and impedance measurement and comparison before and after specific event (rain, hurricane, etc.)
• Making coaxial lines or measuring their parameters
• Cable testing and fault location
• Measuring capacitance or inductance of reactive loads

For the latest software updates, please refer to the manufacturer's website

The following items are included with each RigExpert AA-230PRO order:

• RigExpert AA-230PRO analyzer
• Battery
• Soft case with straps
• Battery charger
• USB cable
• User's manual
• CD with drivers and software

RigExpert AA-230PRO Specifications

Frequency range: 0.3 to 230 MHz

Display modes:

• SWR at single frequency
• SWR, R, X, Z, L, C at single frequency
• SWR graph
• R, X graph
• AA-230PRO: TDR (impulse and step response) graph

Single- and multi-frequency measurement:

• Frequency resolution: 1 kHz
• SWR only mode: easily-readable bar
• SWR range: 1…10
• SWR display for: AA-230PRO: 25, 50, 75 and 100 Ohm systems
• R, X range: 0…1000, -1000…1000 Ohm

SWR and R, X graphs:

• 100 points plot
• Sweep width: 0.01…230 MHz
• Frequency resolution: 1 kHz
• SWR range: 1…10
• SWR display for: AA-230PRO: 25, 50, 75 and 100 Ohm systems
• R, X range: 0…200, -200…200 Ohm
• Memories: AA-230PRO: 90 memories to store and recall graphs
• Presets for radio amateur bands

RF output:

• Connector type: UHF
• Power: typ. 10 dBm

Power:

• 4.8V, 1800 mA•h, Ni-MH battery
• Max. 3 hours of continuous measurement
• Max. 2 days in stand-by mode
• External 9...14V, 500 mA charger
• Full charge time: 10...12 hours

Interface:

• 128x64 graphical LCD with backlit
• 6x3 keys on the water-proof keypad
• Multilingual menus and help screens
• USB connection to a personal computer

Dimensions: 22•10•5.5 cm

Operating temperature: 0…40 °C

Weight: 650g

MultiSWR™ and SWR2Air™ modes

MultiSWR mode

RigExpert Antenna Analyzers have a unique ability to display SWR for up to five different frequencies at a time.

You may use this feature to tune multi-band antennas. Use the up and down cursor keys to select a frequency to be set or changed. Press the 0 key to switch between SWR bars and numerical representation of these parameters.

SWR2Air mode [AA-230/AA-230PRO only]

RigExpert Antenna Analyzers present a new SWR2Air mode which is designed to help in adjusting antennas connected via long cables.

This usually involves two persons; one adjusting the antenna and the other shouting out the SWR value as it changes at the far end of the feedline.

There is an easier way to do the same job by using the SWR2Air mode. The result of SWR measurement is transmitted on a user specified frequency where it can be heard with a portable HF or VHF FM radio.

The length of audio signal coming from the loudspeaker of the portable radio depends on the value of measured SWR.

The SWR2Air mode is activated by pressing the F + OK combination in the SWR measurement screen. F + 2 allows setting the frequency to tune the receiver to.

RigExpert AA-230PRO Time Domain Reflectometer mode

Time domain reflectometers are electronic instruments used for locating faults in transmission lines.

A short electrical pulse is sent over the line, and then a reflected pulse is observed. By knowing the delay between two pulses, the speed of light and the cable velocity factor, the DTF (distance-to-fault) is calculated. The amplitude and the shape of the reflected pulse give the operator idea about the nature of the fault.

Instead of a short pulse, a "step" function may be sent over the cable.

Unlike many other commercially-available reflectometers, the RigExpert AA-230PRO does not send pulses into the cable. Instead, another technique is used. First, R and X (the real and the imaginary part of the impedance) are measured over the whole frequency range (up to 230 MHz). Then, the IFFT (Inverse Fast Fourier Transform) is applied to the data. As a result, impulse response and step response are calculated.

(This method is often called a "Frequency Domain Reflectometry", but the "TDR" term is used in this document since all calculations are made internally and the user can only see the end result.)

The vertical axis of the resulting graphs displays the reflection coefficient: Γ=-1 for short load, 0 for matched impedance load (ZLoad=Z0), or +1 for open load. By knowing the cable velocity factor, the horizontal axis is shown in the units of length.

Single or multiple discontinuities can be displayed on these graphs. While the Impulse Response graph is suitable for measuring distance, the Step Response graph helps in finding the cause of a fault.

See the examples of typical Step Response graphs:

How it works?

Structure diagram

The structure diagram of the RigExpert AA-230PRO Antenna Analyzer is located below:

The "brain" of the analyzer is Atmel ATMEGA128 8-bit RISC microcontroller. It controls the dual-channel AD9958 DDS running at 500 MHz and generating two sinusoidal signals with 90° shift. Both signals are low-pass filtered. The first channel is fed to the amplifier to get the +10 dBm signal at the antenna connector. Resistive brigde was chosen to measure parameters of a load because of its simplicity and good frequency response. The switch commutates two outputs of the bridge. The detector, AD8302, measures the manitude ratio and the phase difference at its two inputs. The resulting signals are then fed into the 16-bit analog-to-digital converter for further processing.

The 128x64 graphical LCD and the 6x3 keys keypad are connected directly to the CPU. Also, it is equipped with 512K of external Flash memory to store measurement results. The USB interface chip allows connecting the analyzer to the PC.

The power circuits are responsible for generating a number of voltage levels needed for the rest of the analyzer. It also charges the built-in battery when the external 12V DC source is applied.

Close look at the bridge

This is a diagram of the resistive bridge and its connection to the detector:

The switch which is controlled by the CPU feeds the signal from the certain side of the bridge to the detector chip. When the load is totally active and its resistance is 50 Ω, the bridge is balanced and the switch outputs the same signal in both positions. This eliminates the need of calibration of the analyzer, also giving very good precision near SWR=1.

The detector compares the output of the switch with a reference 90° signal. This avoids "dead zones" in the phase characteristics of the AD8302 chip. The outputs of the chip are connected to the analog-to-digital converters which are built into the microcontroller.

Connector issue

For the good performance at high frequencies (above 50 MHz) is it important to built almost an ideal, symmetrical bridge. However, the load is plugged into the analyzer through the connector (non-ideal electronic part), which slightly unbalances the bridge. To compensate parameters of the connector, a simple model was chosen:

The microcontroller takes into account tiny capacitance and inductance of the connector, correcting the result of each measurement.

Download Manual

• RigExpert AA-230/AA-230PRO/AA-520 User's manual