45-degree Slant Antenna Polarization:

Signals received at base station antennas are typically elliptically polarized in a way more like vertical polarization than horizontal polarization. This creates a common problem with dual polarized base station antennas (like the first generation of Ubiquiti dual-polarity antennas) since the vertically polarized antenna element generally maintains a stronger receive signal than the horizontally polarized antenna element.

This can be overcome by slanting the orthogonal polarized antenna elements to +/- 45 degrees. By slanting one of the antenna elements 45 degrees to the left and the other 45 degrees to the right, improved equality in received signal levels can be achieved. This can help improve coverage in congested environments.

Another advantage to using these types of cross polarized antennas is in co-located wireless system installations. Since multiple antennas are used within the same facility or tower, this often creates interference issues among antennas which are usually vertically or horizontally polarized. Using 45 degree slanted cross polarized antennas on the client side as well on the base station side can greatly reduce interference and improve performance.

Real-World Polarization Behavior of RF Signals

Signals received at base station antennas are rarely perfectly linearly polarized. In theory, a transmitted signal may be vertically or horizontally polarized, but in practice, RF signals interact with their environment as they propagate. Reflections from buildings, towers, vehicles, terrain, foliage, and other obstacles cause polarization distortion.

As a result, received signals are typically elliptically polarized, with a tendency to be closer to vertical polarization than horizontal polarization. This is especially true in terrestrial wireless systems where vertical structures dominate the environment. This real-world behavior has important implications for antenna design and polarization strategy.

Limitations of Traditional Dual-Polarized Antennas

This polarization behavior creates a common problem with dual-polarized base station antennas, particularly early or first-generation designs such as early Ubiquiti dual-polarity antennas. These antennas typically use one vertically polarized element and one horizontally polarized element to achieve polarization diversity.

In practice:

• The vertically polarized antenna element generally maintains a stronger received signal
• The horizontally polarized antenna element often experiences weaker coupling to the incoming signal
• Signal imbalance reduces the effectiveness of polarization diversity and MIMO techniques

When one polarization dominates, the system cannot fully benefit from dual-polarization. This can result in reduced throughput, inconsistent performance, and diminished coverage—especially in non-line-of-sight or multipath-heavy environments.

How 45-degree Slant Polarization Improves Signal Balance

This imbalance can be overcome by slanting the orthogonal polarized antenna elements to +45 degrees and -45 degrees instead of using pure vertical and horizontal orientations.

By slanting one antenna element 45 degrees to the left and the other 45 degrees to the right:

• Each antenna element captures a more equal component of the incoming elliptically polarized signal
• Received signal levels between antenna ports become more balanced
• Polarization mismatch losses are reduced

Rather than favoring one dominant polarization, ±45° slant polarization distributes energy more evenly across both antenna elements. This improves link stability and makes system performance more predictable under changing environmental conditions.

Benefits in Congested RF Environments

The advantages of 45-degree slant polarization become even more pronounced in congested RF environments, such as:

• Urban wireless networks
• Industrial and manufacturing facilities
• Warehouses and logistics centers
• Campuses, stadiums, and dense enterprise deployments

In these environments, multipath reflections and interference are unavoidable. Slant polarization helps mitigate these effects by reducing polarization sensitivity and maintaining balanced signal reception. The result is:

• Improved coverage consistency
• More stable signal-to-noise ratios (SNR)

Better overall user experience

Interference Reduction in Co-Located Wireless Systems

Another major advantage of 45-degree slanted cross-polarized antennas is their effectiveness in co-located wireless system installations.

When multiple antennas are installed on the same tower, rooftop, or facility, interference issues are common—particularly when most systems use standard vertical or horizontal polarization. Antennas with the same polarization tend to couple strongly with one another, increasing co-channel and adjacent-channel interference.

Using 45-degree slanted cross-polarized antennas on both the client side and the base station side significantly improves polarization isolation. This reduces unwanted coupling between systems and allows multiple networks to operate more efficiently within the same physical space.

Impact on MIMO and Modern Wireless Technologies

Modern wireless technologies—including LTE, 5G, Wi-Fi 5/6/6E, and private LTE/5G networks—rely heavily on MIMO (Multiple Input, Multiple Output) architectures. MIMO performance depends on low correlation and balanced channel conditions between antenna elements.

45-degree slant polarization supports MIMO performance by:

• Improving balance between parallel signal streams
• Reducing polarization-dependent fading
• Enhancing spatial diversity

This makes ±45° slant polarization a preferred choice in many modern base station and client antenna designs.

Practical Deployment Considerations

When deploying antennas with 45-degree slant polarization, several practical considerations should be addressed:

• Alignment accuracy: Antennas must be mounted correctly to maintain true ±45° orientation
• End-to-end consistency: Best results occur when both ends of the link use slant polarization
• Antenna isolation: High-quality antenna designs with good port isolation are essential
• Environmental factors: While slant polarization helps, proper placement and line-of-sight still matter

Many modern antennas are now manufactured with fixed ±45° polarization to simplify installation and ensure consistent performance.

Comparison with Vertical and Horizontal Polarization

Vertical and horizontal polarization schemes are simple and familiar, but they are increasingly limited in dense deployments. In contrast, ±45° slant polarization offers a more robust solution for modern wireless environments.

Key differences include:

• Vertical/horizontal polarization often leads to imbalance and higher interference
• ±45° slant polarization provides better signal equality and isolation
• Slant polarization improves coexistence in multi-system installations

Conclusion

45-degree slant antenna polarization is a proven and effective solution to the signal imbalance and interference issues commonly encountered with traditional dual-polarized antenna systems. By orienting antenna elements at ±45 degrees, wireless networks achieve more balanced signal reception, reduced interference, and improved performance—especially in congested and co-located environments.

As wireless deployments continue to increase in density and complexity, polarization strategy becomes just as important as frequency planning and antenna gain. Incorporating 45-degree slant polarization into modern wireless designs helps maximize system efficiency, improve coverage reliability, and deliver consistent high-performance connectivity.