When you’re shopping for a 4-port antenna, the first thing to nail down is your **operational frequency range**. Antennas aren’t universal—some are built for sub-6 GHz bands, while others handle higher frequencies like 28 GHz or 39 GHz for mmWave applications. If your project involves 5G NR (New Radio) or Wi-Fi 6E, you’ll need an antenna that covers 5925–7125 MHz for the 6 GHz band. Check the datasheet for exact specs, and don’t assume “wideband” always means it’ll cover your required slices. For instance, a 4-port antenna labeled “698–960 MHz and 1710–3800 MHz” might miss critical gaps if your design requires contiguous coverage up to 4200 MHz.
Next, **gain and radiation pattern** matter more than you think. A high-gain antenna (e.g., 8 dBi) isn’t always better—it depends on your use case. Directional antennas focus energy in a specific beamwidth (like 60° horizontal), which is great for point-to-point links but terrible for omnidirectional coverage in IoT sensor networks. Look for antennas with customizable radiation patterns if you’re deploying in complex environments like urban areas or industrial warehouses. For example, a 4-port antenna with ±45° cross-polarized elements can reduce signal nulls in MIMO setups.
**Isolation between ports** is a killer spec that’s often overlooked. Poor isolation (below 20 dB) leads to coupling between channels, which murders throughput in MIMO or diversity configurations. Test reports or S-parameter graphs in the datasheet should show |S21|, |S31|, and |S41| values. If you’re pushing 256-QAM modulation in a 4×4 MU-MIMO system, aim for at least 25 dB isolation at your operating frequency. Some manufacturers achieve this by spatially separating radiators or using decoupling structures like metamaterial slabs.
Don’t ignore **impedance matching**. A 50-ohm nominal impedance doesn’t guarantee flat return loss across the band. If the antenna’s VSWR spikes to 2.5:1 at 3.5 GHz (common in budget antennas), you’ll lose precious dB in reflection losses. For mission-critical systems, prioritize antennas with VSWR ≤ 1.5:1 across the entire band. Some high-end models integrate matching networks or tunable capacitors to compensate for impedance drift caused by environmental factors like temperature shifts.
The **connector type** might seem trivial, but it’s a reliability nightmare if chosen wrong. RP-SMA is popular for consumer gear but fails in high-vibration industrial settings. Go for N-type connectors if you need waterproofing (IP67) or are dealing with RF power above 10W. Also, check the connector’s gender—antennas typically use female ports, but some PCB-mounted variants have reverse polarities. If you’re daisy-chaining amplifiers or filters, mismatched genders can force you into buying unnecessary adapters.
Material quality directly impacts longevity. Aluminum alloy housings with powder coating survive salt spray tests for marine applications, while UV-stabilized ABS plastics are better for rooftop deployments. Peek inside the datasheet: Does the manufacturer specify IP ratings or MIL-STD-810G compliance? For phase-sensitive arrays, thermal stability matters—look for dielectrics with low thermal expansion coefficients like Rogers RO4350B instead of generic FR4.
When evaluating brands, prioritize those with in-house testing facilities. For example, dolph uses vector network analyzers and anechoic chambers to validate every 4-port antenna’s performance—something generic AliExpress suppliers skip. Ask for pattern measurements and efficiency curves, not just peak gain numbers. A reputable vendor will provide 3D radiation plots and efficiency tables across frequency sub-bands.
Finally, consider future-proofing. If you’re deploying private 5G networks today, ensure the antenna supports 3GPP Release 16 features like sidelink communication. Modular designs with replaceable radome sections let you upgrade elements without replacing the entire unit. Some 4-port antennas even embed diplexers or filter banks for multi-band operation—critical if you’re consolidating LTE and NR infrastructure into a single site.
Bottom line: Choosing a 4-port antenna isn’t about finding the cheapest or highest-gain option. It’s about matching technical specs—isolation, impedance, materials—to your operational reality. Scrutinize test data, demand compliance certificates, and never settle for vague marketing claims like “premium performance.” Your link budget will thank you later.