GPS/GNSS Preamplifier (LNA) and Filter description
GPS/GNSS Preamplifier and Filter, model LNAU-1575-648, is a 1560-1605 MHz (1575 MHz/1582 MHz) LNA and Filter combined into a single device. It was designed to enable users to enhance outdoor passive navigation antennas by defining the receiving system's Noise Figure (and Sensitivity) at the antenna's feedpoint. The LNAU-1575-648 provides the signal conditioning needed to offer high-end performance to a low-cost GNSS/GPS receivers and navigation equipment. It does so by filtering the signals twice, by adding 16 (+|-2 dB) of gain (40 times magnification), and providing a low Noise Figure of 1.5 dB to the receiving system. The output filter is very sharp, completely removing unwanted signals outside the immediate vicinity of GNSS receive frequencies.
The LNAU-1575-648 has built-in protection against unintended large RF power levels at either connector. It can survive up to 2 Watts of continuous in-band power at either port; however, while large RF power is present, the Amplifier will either operate at reduced capacity, or disconnect itself, depending on the magnitude of the injection. This makes the LNA very robust. Most preamplifiers will not survive input signals larger than 10 mW (milliWatts). This feature is unique to our LNAU-xxxx-648 family of Low Noise Amplifiers. Variants for other bands and applications are available.
Proper Installation of GPS/GNSS LNA and Filter
This 1575 MHz and 1582 MHz LNA and Filter, like any other preamplifier, should be connected directly to the antenna, or as closely as possible, keeping the length of the connection short. This minimizes the loss at the input, and therefore improving receiving system's Noise Figure. This also means that the sensitivity of the receiver is maximized. Once the LNA contributes its gain, 16 dB or 40 times magnification in this case, the output can be connected to the receiver through a long coaxial cable, if needed, without impairing sensitivity.
For the amplifier to operate, DC power must be provided at the output SMA (Gold) connector. To provide such power through the coaxial cable, a Bias Tee is generally needed, for example our model BIT-1500-385. Normally, the Bias-Tee is located near the receiver and has 3 terminals: one RF Output/Input, one DC input and one common RF + DC port,. The common port is the one that should be connected to the LNA's output.
This preamplifier may be used with our GPS/GNSS antenna, model UC-1574-341RNF (N Female variant ---> Base/Flange type) directly, for fixed site, mobile and portable reception of GPS L1, GLONASS L1, Galileo E1, BeiDou B1, SBAS L1 and QZSS L1 navigation signals simultaneously.
Caution: before enabling any bias tee, make sure that the its output is connected to the target device, and that the output is not a short circuit. The LNAU-1575-648 preamplifier is highly efficient, consuming only 10 mA @ 5V typically.
LNAU-1575-648 Technical Specifications
- Frequency range: 1560-1605 MHz
- Gain: +16 dB +|-2 dB
- Nominal Impedance: 50 ohm (RF) IN/OUT
- Normal Operating Input RF Power: 1 mW (+0 dBm)
- Survivability Input RF Power: 2 Watts CW in-band
- VSWR: 2.0
- Noise Figure: 1.5 dB
- IIP3: +6 dBm (4 mW)
- P1dB: +10 dBm (10 mW)
- Current: <16 mA
- Supply Voltage: 3.3-15 VDC (internally regulated)
- Connector: N Male (Input) / SMA Female (Output + DC)
- Dimensions: L 38 mm (1.5") x OD 28 mm (1.1"), not including connectors
- Mounting: Direct mount
- Operating Temperatures: -40°C to +85°C
- Weight: 100 g / 0.22 lbs
- Shipping Weight: 150 g / 0.3 lbs
- Color: Black (body), Silver and Gold (connectors)