ANT-21 GPS Antenna with 10m Cable

The ANT-21 is a high-performance marine GPS antenna engineered to ensure your onboard electronics receive a strong and accurate satellite signal. Whether you have an AIS transponder that requires an external GPS feed, a chartplotter installed in a below-deck navigation station, or any other marine device needing a better GPS reception, the ANT-21 is up to the task. It’s a compact, durable antenna that can be mounted in an optimal location on your vessel to overcome reception challenges that the device’s factory antenna might face.

As an active GPS antenna, the ANT-21 incorporates an internal low-noise amplifier. This LNA provides roughly 28–30 dB of gain, amplifying the incoming GPS signals significantly before sending them down the line to your receiver. By boosting the signal right at the antenna, the system counteracts the losses that occur over the cable run and improves the signal-to-noise ratio. In practical terms, that means faster satellite lock times and more stable tracking of your position, even in difficult conditions (such as under a cabin roof or in a busy RF environment). The ANT-21 operates on the primary GPS frequency of 1575.42 MHz and will pick up standard GPS satellite transmissions. It also can receive augmentation signals like WAAS/EGNOS if available, since those are broadcast on the same frequency. The antenna is powered via the coaxial cable with a DC voltage of 3 to 5 volts (often provided by the connected AIS or chartplotter’s antenna port), which simplifies installation – no separate power lead is needed, and power consumption is only a few milliamps.

Designed for the marine environment, the ANT-21 features a sealed, weatherproof construction. Internally, its electronics are conformally coated or otherwise protected to withstand humidity and salt air. The antenna is specified to operate from -30°C to +75°C (-22°F to 167°F), so it can handle the heat of tropical sun and the cold of winter mornings at sea. It likely meets IEC 60945 maritime standards, which cover resistance to vibration, shock, temperature, and salt spray (common criteria for marine electronics reliability). This means once you install it topside, you can expect it to perform reliably over the long haul, despite constant exposure to the elements. It’s also a passive device in terms of not needing any user interaction – after installation, it quietly does its job of delivering satellite signals to your equipment.

The ANT-21 comes with a generous 10-meter (approximately 33 feet) RG-58 coax cable terminated with a TNC male connector. RG-58 is a standard 50-ohm coaxial cable commonly used in marine and RF applications; in this case, it’s marine-grade (often RG-58 CU MIL spec) which ensures good performance and corrosion resistance. The length is usually sufficient for most boats to run from the antenna’s mounting location (say, on the hardtop, rail, or arch) to the nav station or electronics locker where your AIS or GPS device resides. If needed, the cable can be shortened or coiled (excess should be managed properly to avoid kinks), but typically 10 m gives enough flexibility for a clean routing path. The TNC connector is a threaded RF connector, providing a secure and weather-resistant link to your device’s GPS port. Many AIS transponders and some chartplotters have a TNC or BNC input for an external GPS antenna, so adapters are rarely required (if an adapter is needed, TNC-to-BNC adapters are inexpensive and easy to source).

By installing the ANT-21 GPS antenna, you effectively ensure that your navigation electronics get a clear “view” of the satellites. AIS transponders, for example, not only transmit your vessel information but also rely on an accurate GPS position to include in their broadcasts – a reliable GPS fix is crucial for AIS to function correctly. Similarly, a dedicated external GPS antenna can benefit a VHF radio with DSC capability or any setup where the GPS receiver is placed in a less-than-ideal location. Users report that after adding an antenna like the ANT-21, their devices achieve and maintain locks more consistently, and the number of satellites in view often increases (because the antenna can receive from the full sky, not just through a window or a narrow opening). The improved reception leads to more precise plotting on your electronic charts and more confidence in the accuracy of your AIS target positions. In summary, the ANT-21 is a reliable, easy-to-install upgrade that ensures your onboard systems are fed with the quality GPS data they need, so you always know your position and can navigate and communicate with greater assurance.