Combo Antenna Technical Specifications: Frequency Bands, Signal Performance, and Selection Guide

How to read a multi-service antenna datasheet without being misled by peak gain

Combo antenna technical specifications are harder to compare than single-service antenna specifications, because a combo part contains two or more radiating systems sharing one housing, one ground plane, and one cable bundle. Each service has its own gain, efficiency, and pattern, and the interaction between them — isolation — is often the parameter that decides whether the product works in the field.

This guide explains what a combo antenna actually combines, which specifications deserve attention and in what order, how isolation and coexistence affect real performance, and how to structure a specification review so that two suppliers can be compared on equal terms.

What a Combo Antenna Combines

The most common configuration pairs a GNSS receiving element with a cellular transceiver covering LTE or 5G bands. A second common variant adds Wi-Fi and Bluetooth for local connectivity, and some designs add a second cellular port for diversity or MIMO.

The reason to combine them is practical: a vehicle, a telematics unit, or a remote terminal has limited roof area and limited cable runs. One housing, one mounting hole, and one cable bundle reduces installation time and eliminates the risk of two antennas interfering mechanically. The cost is engineering complexity inside the housing, and that complexity is where specifications become difficult to compare.

A combo antenna specification should list performance separately for each service and each band group. A single "gain: 3 dBi" line covering a product that operates from 700 MHz to 5.8 GHz is not a specification; it is an average of values that differ by several decibels and a strong hint that the datasheet was written for marketing rather than engineering.

Isolation: The Specification That Decides Real Performance

Isolation describes how much energy from one port reaches another. In a combo antenna it matters for two reasons. First, a cellular transmitter operating close to a GNSS receiver can desensitise the front end, raising the noise floor and reducing the number of satellites the receiver can track. Second, poor isolation between two cellular ports degrades MIMO performance in ways that are difficult to attribute to the antenna once the product is deployed.

Isolation is not a single number. It varies with frequency, and it varies with the ground plane the antenna is mounted on. A datasheet figure measured on an idealised ground plane will not hold on a plastic enclosure with a small metal insert. Ask for the isolation data measured in a configuration comparable to your installation, or plan to measure it yourself with the product assembled.

A practical mitigation that often matters more than the antenna itself is filtering at the receiver input. Even a well-isolated combo antenna will pass some cellular energy into the GNSS path, and a front-end filter that rejects the cellular bands protects the receiver from the adjacent-channel power that leaks through.

Gain, Efficiency, and VSWR: Which Number Means What

Gain is not efficiency

Gain describes how much energy is concentrated in a particular direction relative to an isotropic radiator. Efficiency describes how much of the input power is radiated rather than dissipated as heat. A small combo antenna can show respectable peak gain at a given angle while having modest efficiency, because the pattern is shaped rather than the losses reduced. For a receiver, efficiency and pattern coverage matter more than peak gain, since satellites arrive from many directions.

VSWR and matching bandwidth

A VSWR figure describes how well the antenna is matched to its feed at a given frequency. A combo antenna covering multiple wide bands will have a VSWR curve with peaks and valleys, and a single quoted value usually refers to the best point. Ask for the curve across the operating range, and check the values at the band edges where your device actually transmits.

Polarisation and pattern

GNSS uses right-hand circular polarisation, while cellular links are typically linearly polarised and depend on the orientation of the antenna relative to the base station. In a combo antenna the two systems cannot both be optimised for the same pattern, so the design trades coverage against peak performance. Understanding which trade was made tells you whether the part suits a roof-mounted vehicle or a fixed installation.

Mechanical and Environmental Specifications

Combo antennas are usually mounted where they are hard to service, so the mechanical specification carries as much weight as the RF one.

• Ingress rating and test basis. An IP67 label on a product that is installed horizontally on a roof and exposed to standing water is not equivalent to a test report describing immersion and thermal cycling.
• Housing material and UV stability. ABS without UV stabilisation yellows and becomes brittle within a couple of seasons outdoors. The difference is invisible in a datasheet and obvious after two years.
• Mounting interface. Thread size, gasket type, and torque specification all affect whether the installation stays watertight. Specify them, and specify the cable exit direction, because a cable that leaves the housing in the wrong direction will be bent beyond its minimum radius during installation.
• Cable and connector per port. A combo antenna has several cables. Their type, length, and connectors should be listed individually, along with the loss at the highest operating frequency.

How to Run a Specification Review

Two combo antennas with identical headline numbers can differ substantially once these seven items are compared. The differences usually show up first as a GNSS receiver that loses satellites when the cellular link transmits at full power — a symptom that is easy to blame on the receiver and hard to trace back to isolation.

Yonghao Innovation Antenna Portfolio

Yonghao Innovation Tech is a national high-tech enterprise established in 2014, based in Shenzhen, Guangdong, China. We integrate research, manufacturing, and sales, and we supply GNSS satellite antennas, positioning terminals, data communication products, and customized high-precision BeiDou solutions for surveying and monitoring, aerospace, communication time service, autonomous driving, machine control, and intelligent transportation.

Our combo antenna line sits alongside the RTK GNSS antenna range and is intended for terminals that need positioning and communication through a single roof penetration. Where the application integrates the antenna directly onto the module, the YM-459Q combines the GNSS receiver and antenna in one assembly, which removes the cable and connector losses that a separate combo antenna introduces.

Cable assemblies, mounting gaskets, and connector adapters are listed under accessories, and port configuration or housing changes are handled through our technical support review before any tooling decision.

Conclusion

Comparing combo antenna technical specifications is mostly a matter of refusing to accept aggregate numbers. Gain, VSWR, efficiency, and isolation each need to be stated per band and with the measurement conditions attached, and the mechanical specification needs the same rigour because the part will spend years outdoors. A supplier who can provide that breakdown is telling you how the product was designed; a supplier who cannot is asking you to accept a claim.