RF toolbox | Active LPDA active antenna

RF toolbox Active LPDA

The RF toolbox Active LPDA active antenna makes wireless antenna systems significantly more operationally secure. It maintains the received signal at the correct level, preventing intermodulation distortion and suppressing noise signals.

Example situations

1- At a performance that takes place in different locations, there are a number of antenna arrangements for wireless microphones. The same microphones are used at the various locations. Not only do the antennas require large cable lengths to be bridged, it also gives a considerable improvement when the receivers can be switched between the different locations.

2- On a small stage, four actors with wireless microphones stand in the wings near the antennas waiting to go on. This is very likely to seriously hamper the reception of those four transmitters by creating intermodulation.

Considerations

1- On receivers of wireless microphone receivers, the sensitivity to the incoming signal cannot be adjusted. Thus, no compensation can be made for signal loss at extreme cable lengths.

2- When transmitters are close together at a small distance from the antenna, the sensitivity of that antenna must be attenuated, otherwise there is a risk of distortion. If there is a change in the situation, such as movements on stage where transmitters physically end up in different positions and thus the signals come in at a lower level, the sensitivity no longer needs to be attenuated.

Solutions

On the RF toolbox LPDA, the gain can be adjusted through three stages of amplification. By amplifying the signal, losses due to large cable lengths can be compensated.

The RF toolbox LPDA can attenuate the signal to counter intermodulation and lower the noise floor. This makes the signal cleaner and thus easier to process within receivers.

There is an Auto Gain function in the RF toolbox LPDA. This ensures that the emitted signal is within the optimum range for the receivers under all conditions. This prevents intermodulation and provides a high dynamic range.

The remotely controlled RF toolbox LPDA in combination with passive splitters also makes it possible to place antennas in different zones, thus immensely increasing the coverage of the antenna systems without having to increase the sensitivity (no increase in the noise floor) and turning zones on and off independently of each other. Using the antenna distribution systems RF-toolbox XL and RF-toolbox Splitter 8, up to 32 RF-toolbox LPDAs can be remotely controlled.

General

The RF-toolbox LPDA features a generous display (1.3-inch, 128 x 64 pixels, OLED) on which the gain/attenuation can be configured and the necessary settings can be made.

The gain range is huge (-20 to + 30dB), making it suitable for both small stages, and venues where long coaxial cables are deployed.

The RF toolbox LPDA is powered via coaxial cable, and digital communication with the RF toolbox XL and Splitter-8 is also via the same cable.

The RF toolbox LPDA takes a big step in improving wireless transmission of microphone signals. Systems from 'big' brands do not specifically address the mentioned shortcomings, while users of especially bulky transmitter/receiver systems have to face these problems on a daily basis.

RF-toolbox LPDA can be used standalone, but is also part of a total system that can filter, amplify, attenuate and distribute wireless microphone signals, and contributes significantly to the reliability of wireless microphone systems. RF Toolbox's products can be gebruit in combination with the most common brands such as Shure and Sennheiser.

Technical specifications:

• Power supply: 100mA @ 13V, switch-mode power supply / 9 - 25V DC,
• Three-stage preamplification in 0.5dB steps / OIP3 > 38dBm

Stage1: -20 - 0dB gain, 10mA @12V

Stage2: 0.5 - 16dB, 50mA @12V (also for sets such as the Sennheiser EW series)

Stage 3: 16 - 30dB, 110mA @12V

• Frequency range: 470 - 750MHz (other bandwidths on request)
• Linearity: +/- 1dB
• Noise: 0.8dB @ at full output
• Remote controlled by RF-toolbox XL or RF-toolbox Splitter-8 (maximum 32)
• Dimensions (lxwxh): 290 x 292 x 50mm
• Housing and fixing points: robust, anodised aluminium
• Currently being tested for IP rating IP54.

Adjustable on the antenna:

• Gain -20 ~ +30dB (Auto Select at amplifier stage)
• AGC (auto gain control) -40 ~ +20dBm threshold / max. 31db gain reduction
• Maximum gain: -20 ~ 0dB / -20 ~ +16dB / -20 ~ +30dB, manually adjustable
• ID number for communication with RF toolbox splitter-8 and XL.
• RF level readable on OLED -55 to +20 dBm (graphical and numerical value)
• Test function for measuring minimum and maximum received signal level
• Display: upside-down display, backlight dim and delay time dimming function

Working prototypes are currently undergoing field tests and can be tried out on request.