Selection Guides

How to Specify a GPS/GNSS RF Cable Assembly for Antenna to Receiver Links

01/16/2026

A GPS/GNSS RF cable assembly is best defined from the antenna and receiver requirements first. The two device interfaces determine the connector ends, the supported GNSS bands define where RF performance needs to be checked, and the receiver and antenna specifications set the usable loss conditions. Cable length, routing space, active antenna power, and the required acceptance data then turn those system inputs into a finished cable assembly specification.

Table Of Contents

Antenna and Receiver Requirements
Check the Complete RF Path Loss
Cable Length and Loss Need to Be Checked Together
Active GNSS Antennas Add a DC Requirement
FAQ
Conclusion

Antenna and Receiver Requirements

GPS operates in the L-band portion of the radio spectrum, where signal propagation characteristics are well suited for satellite-based navigation. The most widely used GPS frequencies include L1 (1575.42 MHz), L2 (1227.60 MHz), and L5 (1176.45 MHz). Among them, L1 is the most commonly supported band in commercial and industrial GNSS receivers, while L2 and L5 are increasingly used in professional and high-precision applications.

For cable assembly work, the receiver and antenna documentation matters more than a general list of GNSS frequencies. Record every band used by the selected equipment and use those frequencies when checking cable attenuation and the finished assembly. A multi constellation receiver may use GPS, Galileo, GLONASS, BeiDou, or other signals, so the cable specification needs to follow the bands supported by that particular receiver and antenna combination.

Check the Complete RF Path Loss

The attenuation value in a coaxial cable datasheet describes the cable itself at a stated frequency and unit length. It does not verify the insertion loss of the finished GPS/GNSS RF cable assembly. Connector terminations, transitions, and mismatch in the completed assembly can change the measured result.

For an initial estimate, take the cable attenuation at the required GNSS frequency and apply it to the finished length. Use that result to decide whether the selected cable construction leaves enough margin for the assembly. When insertion loss is a release criterion, the final value is better taken from an S21 measurement of the completed assembly at the defined GNSS frequencies or across the required sweep range.

The larger system path may contain an adaptor, splitter, surge protection device, or another RF interface outside the cable assembly. Those components belong in the system loss calculation even though they are not part of the cable assembly drawing. Keeping these two levels separate prevents a cable datasheet value from being mistaken for the complete antenna to receiver loss.

Cable Length and Loss Need to Be Checked Together

A GNSS antenna cable does not have one universal maximum length. The usable length depends on the attenuation of the selected coax at the required frequencies and the loss condition allowed by the antenna and receiver combination.

The attenuation value in a cable datasheet describes the coax at a stated frequency and unit length. An initial estimate can be made from:
Estimated cable loss = attenuation at the required frequency × finished cable length

This estimate covers the cable contribution. The finished cable assembly also contains connector terminations, so an assembly level insertion loss requirement gives a clearer acceptance condition when the GNSS system has a defined loss limit. If insertion loss or VSWR is specified for acceptance, record the corresponding frequency together with the limit.

A longer route may require a lower attenuation coaxial cable. Increasing cable size can reduce attenuation, but it also changes cable OD, bend space and connector termination. The selected cable therefore needs to fit both the available loss condition and the physical route.

Active GNSS Antennas Add a DC Requirement

Some GNSS receivers provide power to an active antenna through the RF port and coaxial cable. In this arrangement, the cable assembly carries the GNSS RF signal and also provides the DC path to the antenna LNA.

The antenna supply voltage and current need to match the antenna power output available from the receiver. For a longer cable, conductor resistance and voltage drop may also need to be checked. A passive antenna does not require this antenna power path, although its RF frequency, impedance, connector and loss requirements still remain.

FAQ

Q1: Why are GNSS systems more sensitive to cable loss than other RF applications?

GNSS receivers operate with signals that arrive at extremely low power levels, often well below the thermal noise floor. System performance depends on maintaining sufficient carrier-to-noise density at the receiver front end. Any insertion loss introduced by coaxial cables, connectors, or adaptors directly reduces this margin.
Unlike many terrestrial RF systems, GNSS links have limited tolerance for additional attenuation, making cable loss a critical design parameter rather than a secondary consideration.

Q2: Does using a longer coaxial cable always reduce GNSS positioning accuracy?

Longer coaxial cables increase total insertion loss, which can reduce signal quality at the receiver. However, reduced positioning accuracy is not solely determined by cable length. The impact depends on cable attenuation characteristics, connector quality, and whether an active antenna with sufficient gain is used.
When properly designed with low-loss cables and appropriate system margin, longer cable runs can still support reliable GNSS performance.

Q3: Can any RF coaxial cable be used for GPS or GNSS applications?

Not all RF coaxial cables are suitable for GNSS systems. Cables designed for GNSS applications must maintain stable impedance, adequate shielding effectiveness, and predictable attenuation across the L-band frequency range.
Using inappropriate cable types can introduce excessive loss, impedance mismatch, or susceptibility to interference, all of which may degrade GNSS signal reception.

Q4: What role does the coaxial cable play in powering active GNSS antennas?

In active GNSS systems, the coaxial cable carries both the RF signal and DC power to the antenna’s low-noise amplifier through a Bias-T configuration. The cable must therefore support stable RF transmission while also providing reliable DC power delivery.
Excessive resistance, poor shielding, or inconsistent cable quality can affect amplifier operation and overall system stability.

Q5: What should OEMs prioritize when selecting RF cable assemblies for GNSS products?

For OEM applications, consistency and repeatability are often more critical than marginal differences in attenuation. Cable assemblies should deliver predictable RF performance across production batches, with controlled termination processes and stable connector interfaces.
Reliable manufacturing quality helps ensure that GNSS performance remains consistent as products scale from prototypes to high-volume production.

Conclusion

In GPS and GNSS systems, RF cable assemblies are not passive accessories but integral components of the signal chain. Cable attenuation, connector quality, and assembly consistency directly influence signal integrity, system stability, and positioning reliability.

Selecting the right GNSS RF cable assembly therefore requires a balanced evaluation of electrical performance, mechanical constraints, and application-specific requirements. By treating the cable assembly as part of the overall system design rather than an afterthought, engineers and procurement teams can achieve more predictable and reliable GNSS performance across a wide range of applications.

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