Choosing a GNSS Antenna Surge Protector

A GNSS coaxial surge protector must fit both the RF path and the antenna-power path. If a receiver powers an active antenna through the same coaxial cable, a protector that blocks that DC path is not a drop-in replacement, even when its connectors and RF frequency range fit. Select the protection device for the documented installation and electrical limits; do not treat a lightning-arrestor label as an anti-jamming function.

Decide which protection you are buying

Surge protection concerns transient electrical energy reaching equipment through an installed connection. RF anti-jamming concerns interference affecting GNSS reception. These are different purchase requirements. A coaxial surge protector does not, by that description, provide spatial interference suppression; an anti-jamming label does not establish a surge withstand rating.

For a rooftop antenna, outdoor machine or fixed GNSS installation, keep the electrical-protection scope separate from the reception-protection scope. The monitoring versus anti-jamming guide covers the latter. This guide concerns selecting an inline coaxial protection component, not designing a building lightning-protection system.

Follow the DC power route before choosing DC pass or DC block

DC pass means the specified device permits the intended DC feed to continue through its documented path. DC block interrupts that path. Identify where power is injected and where it must arrive, rather than selecting solely from the antenna’s name.

HUBER+SUHNER’s surge-protector overview gives concrete alternatives: standard 3401 gas-discharge-tube designs provide DC continuity, while some variants are internally DC blocked; the 3403 family provides DC continuity for remote powering. Its 3408 family blocks DC on the protected side and can incorporate DC injection. These are that manufacturer’s design descriptions, not interchangeable GNSS accessories or ResiNav recommendations.

Conceptual power route: receiver bias supply → coaxial protector → active antenna. In that arrangement, blocking the feed between the source and antenna prevents the assumed power arrangement from working. With a separately documented antenna-side injector, the DC requirement at the protector can differ. The injector’s own supply and protection remain part of the installation. The splitter-selection guide explains why DC routes also matter when multiple receivers share an antenna.

Compare two offers without changing the assumed installation

Hypothetical comparison, not product specifications or a ResiNav connection diagram: assume a GPS L1 active antenna requires a 5 V, 80 mA feed from its receiver. Both offered protectors have a documented RF range containing the required signal, 50 Ω impedance, matching connectors and acceptable insertion loss for this assumed path. Offer A specifies DC pass rated for this voltage and current; Offer B blocks DC and includes no injector. Their surge ratings have not yet been compared.

The useful result is an exclusion or a conditional shortlist, not a compatibility guarantee. A larger advertised surge-current number would not repair Offer B’s interrupted DC feed in the original arrangement. Conversely, DC continuity alone is not enough to accept Offer A.

Compare the protection rating and the installed RF path separately

Compare surge-current claims only with their stated test waveform and conditions. Also compare the documented residual voltage or energy reaching the protected side, the protected equipment’s limits, and the required bonding and mounting arrangement. These are different fields; do not select from the largest current number alone. HUBER+SUHNER distinguishes current handling from residual pulse reduction in its product families and notes that some miniature protectors need different or additional devices for lightning protection.

Times Microwave’s TimesProtect technical brochure, printed pages 11–12, explains protection in terms of the grounded coaxial system and distinguishes RF protection from arrangements that must also carry DC. Buying an inline part is not a substitute for the required bonding and installation. Have the site protection design and installation addressed by qualified personnel under the applicable requirements; this article supplies no grounding dimensions or safety approval.

At every required GNSS band, check the exact protector’s frequency range, insertion loss, impedance and connector arrangement. Add its documented loss to the existing RF-path budget. A connector match does not establish band coverage. A low-loss or DC-pass specification does not establish the required electrical protection.

Keep the order scopes distinct

For the protection-component order, identify the exact variant, any required replaceable protection element, mounting or bonding items, and the intended DC arrangement. For example, HUBER+SUHNER says its 3402 family is normally supplied without the gas tube so that the application-appropriate tube can be selected. A family name alone may therefore leave the order incomplete.

If RF interference protection is also required, compare the published ResiNav anti-jamming product configurations as a separate scope. This guide does not establish that a surge protector is included with, compatible with, or approved for a ResiNav terminal. Do not apply a receiver-fed active-antenna drawing to a terminal’s ports without the model-specific interface definition.

You can start a ResiNav product enquiry with the model or application and information already available; a complete engineering brief is not required for first contact. Identify any proposed external protector as a separate component. Configuration and connection details can then be resolved during quotation without treating that accessory as an already approved part of the product.