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¶ General Description
The Alpha 45 is a compact, waterproof, self-adhesive GPS antenna designed for reliable L1-band performance. Delivering strong top-hemisphere RHCP gain between 26–33 dBiC, the Alpha 45 also maintains excellent top-hemisphere uniformity with consistent performance across 90° and 120° angular sectors from zenith.
This gain stability, combined with low VSWR and Axial Ratio, ensures efficient signal transfer, dependable satellite visibility and reduced fix times in outdoor environments. The integrated low-noise amplifier enhances weak signals, providing robust performance for vehicle tracking, fleet management, asset monitoring and GPS timing systems.
Supplied as standard with an SMA Male connector and 1 m, 2 m or 5 m RG174 cable. Alternative cable lengths can be specified for high-volume projects.
¶ Key Features
- Supports GPS L1, Galileo E1, BeiDou B1C, and QZSS L1
- Top hemisphere RHCP gain between 26-33 dBiC
- Return loss of up to -19.46 dB
- Consistent coverage across ±90° and ±120° from zenith
- Compact, rugged water-resistant design with magnetic and adhesive mount
¶ Typical Applications
- Vehicle and fleet tracking
- Asset monitoring and telematics
- Outdoor GNSS positioning and timing
- Smart infrastructure and IoT
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GPS L1 Antenna
Active GNSS
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Water Resistant
Outdoor Radome
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RHCP Polarisation
GNSS Optimised
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Magnetic Mounting
Quick Installation
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Low-Profile Design
Compact Installation
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¶ Electrical Specifications
| Impedance: | 50 Ohm |
| Polarisation: | RHCP |
| Frequency Range: | 1575.42 MHz |
| Return Loss: | -19.46 dB |
| VSWR: | 1.24 |
| Ground plane independent: | No (tested on 70 x 70 mm ground plane) |
| RHCP Gain at Zenith: | 33.18 dBiC |
| Axial Ratio at Zenith: | 5.04 dB |
| Supply Voltage: | 3 - 5 V DC |
| Current Consumption: | 15.5 mA @ 5 V |
¶ Environmental Specifications
| Operating Temperature range: | -40°C to 80 °C |
| Storage Temperature range: | -40°C to 80 °C |
¶ Mechanical Specifications
| Dimensions: | L = 49 mm W = 39 mm H = 15.5 mm |
| Weight: | 40 g |
| Cable Type: | RG174 |
| Cable Length: | 1 m, 2.5 m, 5 m or alternative |
| Connector: | SMA Male |
| Mounting method: | Magnetic / Adhesive |
| Housing materials: | ABS Radome |
¶ Spectrum Coverage*
| ↑ Suitable band | □ Adequate band in good signal conditions | ↓ Likely to be unsuitable |
¶ GNSS Standards Band Support
| Electrical Interface | Spherical RF Measurements | |||||
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| Centre Frequency (MHz) | VSWR | Return Loss (dB) | Average RHCP Gain (dBiC) | Peak RHCP Gain (dBiC) | Median Axial Ratio (dB) | Minimum Axial Ratio (dB) |
| 1575.42 | 1.2383 | -19.4560 | 26.33 | 33.73 | 5.41 | 1.39 |
| Top Hemisphere RF Measurements | Zenith RF Measurements | |||||
|---|---|---|---|---|---|---|
| Centre Frequency (MHz) | Average RHCP Gain (dBiC) | Peak RHCP Gain (dBiC) | Median Axial Ratio (dB) | Minimum Axial Ratio (dB) | RHCP Gain at Zenith (dBiC) | Axial Ratio at Zenith (dB) |
| 1575.42 | 30.75 | 33.73 | 4.48 | 2.09 | 33.18 | 5.04 |
¶ RF Matching Performance
This section illustrates the antenna's impedance matching characteristics across the operating frequency range using VSWR and Return Loss measurements.
¶ RF Zenith
¶ RF Top Hemisphere
¶ RF Spherical
The following graphs display the Average and Peak RHCP Gain across the entire spherical coverage of the antenna. These metrics provide a comprehensive view of the antenna’s ability to receive signals from satellites at all elevations and directions.
Consistently high gain across the sphere ensures strong and stable GNSS reception in a variety of operating conditions.
¶ ZX and YZ Plane Axial Ratio Plots (Zenith is at 0 degrees)
The following graph shows how well the antenna maintains circular polarisation at different elevation angles. A lower axial ratio ensures better GNSS signal reception, especially at low elevations, which is crucial for applications requiring strong performance in obstructed environments or wide-angle satellite visibility.
¶ Test Setup (on 70 x 70 mm Ground Plane)
¶ 2D Radiation Plots (1575.42 MHz)
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¶ 3D Radiation Plots (1575.42 MHz)
¶ Ordering Details
| Part Number | Description |
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| ALPHA45/1M/SMAM/S/S/48 |
Compact Active Single-Band GPS L1 Adhesive Antenna 1 Metre Cable RG174 and SMA Male Connector |
| ALPHA45/2.5M/SMAM/S/48 |
Compact Active Single-Band GPS L1 Adhesive Antenna 2.5 Metre RG174 Cable and SMA Male Connector |
| ALPHA45/5M/SMAM/S/S/48 |
Compact Active Single-Band GPS L1 Adhesive Antenna 5 Metre RG174 Cable and SMA Male Connector |