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A Primer on Poynting XPOL Antennas

A Primer on Poynting XPOL Antennas

6 May 2022 | 8 min read

Quick Summary

Cross polarisation is a type of diversity technique capable of minimising signal loss within a cellular network by handling polarisation shifts. Learn what that means here!

Among Poynting’s diverse array of antennas, their XPOL range of cross-polarised antennas delivers a stellar balance of performance, ease of use and cost-effectiveness.

In this article, we’ll outline the differences between each model in the Poynting XPOL range.

But first, what is cross polarisation and why would you want it in your antennas?

What is Cross Polarisation (XPOL)?

Diversity Techniques

Cross polarisation is a kind of diversity technique.

‘Diversity technique’, as a term, describes any system wherein 2+ antennas work together to improve the quality and reliability of a wireless network.

There are two primary diversity techniques:

  1. Polarisation diversity
  2. Spatial diversity

Before we go further it’ll help to understand what polarisation is.

What is Polarisation?

There are three types of antenna polarisation: linear, circular and elliptical.  Practically, linear polarisation is the most pertinent for most fixed wireless access applications and can be subdivided into horizontal and vertical polarisations.

When an RF signal meets an obstacle, it will reflect and refract around that obstacle.  This can result in what’s known as a polarisation shift.

For example, a vertically polarised signal can, by the time it reaches a receiving antenna, become horizontally polarised.

When the signal polarisation is out of sync with that of the antenna, the antenna can’t receive the signal at full strength.  In fact, reception is so impaired that an observer would see signal loss of up to -34dB.

Note: Since dB is a logarithmic metric, this means the received signal is more than 2000x weaker than it would be if the antenna and signal had matching polarisations.

Cross Polarisation

By utilising two antennas in the same system, mounted together but set at right angles to each other, each antenna achieves a different polarisation.

This way, the maximum discrepancy between the polarisation of a signal and an antenna in the system becomes 45º rather than 90º.  The result is a maximum signal loss of just -3dB, equivalent to a halving of the signal strength, rather than one that’s more than 2000x weaker.  Quite the improvement!

How Does Cross Polarisation Help In Cellular Network Design?

Cross polarisation limits how out of phase with any antenna in the system a received signal can be.  This minimises the maximum loss in signal strength a system can experience (at least, as a result of polarisation shifts).

Given the large number of variables involved in any given cellular network’s performance, it pays to use polarisation diversity to mitigate the negative impact of any reflections and refractions outside your control.

Thankfully, quality products exist that employ multiple antennas within a single enclosure, meaning you only have to purchase a single product to leverage polarisation diversity to your network’s advantage.

 

The Poynting Range of XPOL Antennas

Poynting’s variety of cross-polarised (XPOL) antennas represents one such range of products - and they’re the best we know of.

But which model is right for you?

Here’s a rundown of each antenna and its key qualities.

 

XPOL-1-X vs XPOL-2-X

In Poynting’s naming convention, XPOL-1- variants are omnidirectional antennas, while XPOL-2- variants are uni-directional.

All antennas in the XPOL range are cross polarised, so while Poynting offers other omni- and uni-directional antennas, you can be sure that those within the XPOL range offer polarisation diversity.

 

XPOL-1-5G

poynting xpol-1-5g cross polarised omni antennas

Poynting’s XPOL-1-5G is an omnidirectional, cross-polarised antenna with a small footprint and 3dBi peak gain, rarely falling below 2dBi of gain across all serviced frequencies.

The antenna’s gain is higher and more stable across the higher frequencies.  As a smaller omnidirectional antenna best employed in urban environments, this is what you’d expect (and what you’d want, too!).

Note: cellular networks in urban areas will be served on higher frequencies than those in remote areas.

The XPOL-1-5G is, naturally, 5G ready on the 3300-3800MHz CBRS band (with 2dBi of peak gain across this band).

The antenna ships with a fixed attachment of 5m of HDF195 5mm coaxial cable, which experiences signal loss at around 0.6dB per metre at 2600MHz (a viable higher frequency for 4G/LTE).  With 3dBi of peak gain at this frequency, this sets the net gain on the system to 0dB.

Note: Remember that mounting a capable antenna outside your building will result in a 15dB increase in gain.  That’s a result of removing all the catastrophic attenuation and destructive interference an RF signal experiences indoors.

For that reason, this antenna is best suited for urban environments, utilising higher frequencies, where the primary improvement on the network can come from installing the antenna outside.

Both 2x2 and 4x4 MIMO variants of the XPOL-1-5G are available, so customers looking for ultimate stability and throughput should opt for the 4x4 MIMO model.

This antenna is cost-effective and small, making it an affordable way to drastically boost performance on a 4G or 5G cellular network.

 

XPOL-1

Poynting’s older XPOL-1 model is EOL, meaning it’s being phased out.  It’s still available for purchase, but customers would do better considering the XPOL-1-5G as the upgraded model.

 

XPOL-2-5G

poynting xpol-2-5g cross polarised directional mimo antenna

The XPOL-2-5G is a 5G-ready cellular and WiFi cross polarised directional antenna providing 2x2 MIMO on the client-side.

As a directional antenna, the XPOL-2-5G’s peak gain across all frequencies is naturally much higher than that of an omnidirectional antenna like the XPOL-1-5G.

Peak gain across all bands is 11dBi, while the average across both lower and higher 4G/LTE frequencies is 9dBi.

Like the XPOL-1-5G, the XPOL-2-5G comes with 5m of attached HDF195 cable.  With the higher peak gain across frequencies and with the increased likelihood of using the lower frequencies in rural/suburban areas, the net gain on the system (including signal loss over the cable) is likely to hover around 7dB.

Compared with highly directional antennas like the LPDA-92 (offering a very stable 11dBi across all served frequencies from 698-2700MHz), the XPOL-2-5G is far more accessible for those without access to professional-grade setup equipment for precise antenna orientation.

In other words, the XPOL-2-5G is more forgiving in its setup than the LPDA thanks to its cross-polarisation, lower peak gain and wider beamwidth.

XPOL-2-V2

For most intents and purposes, the XPOL-2-V2 has been superseded by the XPOL-2-5G (discussed above).  However, due to some subtle differences in the performance metrics of this older variant with its younger counterpart, this model is still in production.

First, and most crucially, this older variant is not 5G ready and only serves 4G/LTE and older technologies.

However, if we hold the gain-by-frequency diagrams side by side, we see that the gain in the 980-1710MHz band (not formally served) is actually extremely stable vs that of the XPOL-2-5G (where it is far more variable).

This makes the XPOL-2-V2 very usable for those frequencies which, though not widely adopted, some providers still employ.  Most notably, the Three (3) network in the UK broadcasts its 4G service, in part, on the 1400MHz band, which the XPOL-2-V2 serves with a peak gain of 6-7dB vs almost 0dB in the XPOL-2-5G.

gain by frequency graph for the poynting xpol-2-v2
Above: Gain by frequency: XPOL-2-V2. Very usable gain between 1000-1700MHz.
gain by frequency graph for the poynting xpol-2-5g
Above: Gain by frequency: XPOL-2-5G

The frequencies that providers use to broadcast their cellular services are region-dependent.  Though the XPOL-2-V2 is not 5G ready and has lower gain on the frequencies most users will be interested in (those shaded yellow/grey), if your service is provided by a carrier that broadcasts somewhere between 1000-1700MHz, the XPOL-2-V2 is the model to go with.

XPOL-6 and XPOL-16

Poynting xpol-16 directional specialty antenna

In addition to the XPOL-2 variants, Poynting also offers two more cross-polarised uni-directional antennas in the XPOL-6 and XPOL-16.

The XPOL-6 is a specialised antenna that offers incredibly stable gain across a narrower range of frequencies.  It deals specifically with the higher 4G/LTE frequencies, WiFi at 2.4GHz, 2G GSM and 3G.

The XPOL-16, by contrast, aims to serve those same 2G GSM and 3G frequencies, as well as the 4G/LTE frequencies at the lower end of the spectrum, including 450-470MHz and 790-860MHz.  Again, this antenna aims to provide exceptionally consistent gain values across its more specialised range of frequencies.

For these reasons, these antennas will offer exceptionally reliable performance for those users certain of the frequencies they’re looking to operate on.

Take a look at their gain-by-frequency graphs to see just how stable the gain values are:

gain vs frequency graph for poynting xpol-6
Above: XPOL-6 gain by frequency graph
gain vs frequency graph for poynting xpol-16 antenna
Above: XPOL-16 gain by frequency graph

 

EPNT-1 and 2

New to the Poynting lineup of cross polarised antennas, the EPNT-1 and EPNT-2 offer omni- and uni-directional solutions (respectively) for minimising the length of coaxial cable used in the system.

ePoynt antenna enclosures are designed for the user to open them up and mount their cellular router/modem within the enclosure itself.

That means inches of coaxial cable rather than metres, mitigating signal loss before the signal is digitised within the modem and transported to a gateway over ethernet cable (wherein signal loss is negligible).

Especially for those applications where the antenna must be mounted far from other network devices, or for any user looking to minimise signal loss, the new ePoynt series is an exciting prospect.

Buy Poynting Antennas Today

If you’re looking for expertly engineered, craftily designed antennas to boost the performance of your networks, look no further than Poynting antennas.  Browse our antenna stock now and purchase yours today.

For more information on the products discussed in this article, head to the respective product page and check out the datasheet linked to at the bottom of the product description.

A Primer on Poynting XPOL Antennas