Wi-Fi Antenna Parameters Under Control

It's Not Just About Covering a Large Area

You must not fall into the often accepted belief that more expensive is also much better in quality. The selection needs to be adjusted to the requirements so that you do not invest unnecessarily in an inappropriate type of antenna or have to consider another one shortly, which will complement the performance of the original, unnecessarily undersized one. The smallest antennas, which we mostly find included in the box with a card or access point, are not as bad as many claim. They are perfectly adequate for covering a typical apartment or small office, but they are not very suitable for outdoor use. Many factors can negatively affect them, such as adverse weather, obstacles in the signal path, or any interference on nearby frequency (most often in the 2.4 GHz band).

You should also be considerate and use directional antennas for greater distances, which will not cause problems to anyone in the vicinity. Obstacles make things a bit more complicated; some allow the signal to pass through without issue, while others weaken or completely attenuate it (the worst for this are iron-reinforced walls or metal structures). It gets a bit more complicated, for example, with trees. In winter (when bare, without leaves), they are not a serious problem, but if they are densely leafy and also wet, they can significantly limit the signal. Coniferous trees are problematic all year round.

Directing the Antenna? Yes, It Deserves Attention!

For simplicity, antennas can be divided into three basic groups based on their direction:

If you want to connect two points over a significant distance, a DIRECTIONAL ANTENNA is a suitable solution. This type of transmitting antenna emits the signal practically only in one direction and to a specific point. You can choose a parabolic one (most often with a wire grid) or opt for the type known as YAGI.

So-called OMNI-DIRECTIONAL ANTENNAS cover a full 360⁰, i.e., they transmit in all directions. They are often included with many Wi-Fi devices. In an apartment, we value them for connecting computers that are irregularly placed or for other devices whose position we occasionally change (notebooks, laptops, mobile phones, etc.). If they have higher performance, they can reliably serve to connect clients in various directions.

The third type is SECTOR ANTENNAS, which only cover a specific desired angle (most often from 30⁰ to 180⁰). Using these antennas can easily and effectively prevent signal propagation in unwanted directions.

Radiation Angle, Polarization, and Gain

These values are also very important for the antenna and should be considered when choosing. The radiation angle is given for the antenna in the horizontal and vertical planes (horizontal and vertical), which is the expression of the angle in which the antenna can provide reliable coverage. For sector antennas, this is usually just a certain segment of a circle, while omni-directional antennas most often cover the full 360⁰.

Polarization refers to the plane in which radio waves propagate, and matching polarization on both sides of the antenna is ideal for good connection; otherwise, significant losses and gain reduction can occur. However, by changing polarization, unwanted interference caused by other networks, when overlapping occurs, can be suppressed.

Gain can be simply expressed as the ratio between the strength of radiation in a given direction versus the intensity, which is the level of energy that can be received by the antenna.

When Choosing a Specific Antenna

The actual range of the antenna is a very important variable, which can sometimes differ significantly from the figures provided by the manufacturer, depending on local conditions. In a hilly terrain with obstacles, it is better to choose a type with slightly higher performance and therefore reach. You can orient yourself by considering that the greater the distance for the required transmission, the greater the gain the antenna should have. Most often, you will receive an ordinary, cheap version of the antenna with Wi-Fi equipment, which is mainly sufficient for home use. This typically does not have a gain higher than 1 to 2 dBi (decibels isotropic). For larger coverage, choose an antenna with greater gain and ensure its optimal placement. You also choose the antenna according to the method and difficulty of installation and connection, usually also considering its shape, size, weight, and color, but these things should definitely not be considered the most important. Home-made Wi-Fi antennas are also feasible, but very few people venture into it.