When it comes to aligning an antenna, it depends on your antenna type if you need aligning after all. Directional antennas need to be aligned, while omnidirectional antennas should not. Here’s a quick recap if you need clarification on the difference between a directional and an omnidirectional antenna.
Omnidirectional vs Directional Antenna
An omnidirectional antenna transmits and receives signals in all directions. On the other hand, a directional antenna radiates in one specific direction, which can be either wide or narrow. The angle within which the signal is stronger is the antenna’s opening angle.
An omnidirectional antenna can receive and transmit signals to and from base stations in all directions. In contrast, a directional antenna must be aligned towards a single mast to receive the best signal. If you have one, you can compare it to a TV antenna on your roof (if you are old enough to remember these, if not, google). Directional antennas provide higher performance because they usually have higher gain, but they must be installed correctly and appropriately aligned. Orientation and position are the two most essential factors in ensuring an antenna functions appropriately.
Here’s how to align an antenna:
Step 1: Locate the Base Station
The first step is to find the location of the nearest base station. If you’re working with your own network you designed, built and operate, you already know where the antenna should point. However, if you have a subscription plan, I recommend contacting your service provider and asking them for the correct bearing to the nearest base station.
Step 2: Determine the Correct Height
If you are far from a base station, the height of the antenna can make a significant difference. Generally, placing the antenna at a higher position is preferable because you usually get a better line of sight, meaning you overcome obstacles that can attenuate the signal between your antenna and the base station. Signal strength on a rooftop is usually much better than on a lower facade.
The height of the antenna is crucial for ensuring optimal installation and achieving the best system performance. The general rule of thumb is to install the antenna as high as possible. Still, sometimes the antenna may have weaker coverage at the maximum height due to reflections or obstacles. In such cases, the height can be adjusted downwards to achieve the best possible performance, although it’s not the norm.
Step 3: How to Measure Performance
Signal and quality can fluctuate, and the signal can quickly change by as much as 12 dB. A measurement taken a few moments later can vary significantly due to various radio aspects such as fading, reflections, refractions, interferences, and capacity variations in the networks. As a consequence, performance can change significantly in a short period.
When finding the right direction for the antenna, we always recommend testing with the specific hardware you will use. Advanced devices such as routers and modems are straightforward when displaying the signal strength and quality of the mobile network; in many cases, you can see the current status in the admin menu. In contrast, simpler devices may have different features.
If you have a device that can show the signal strength, you can use it for measurement. Otherwise, you will need separate measurement equipment. The best approach is to perform a measurement and test by realigning the antenna. I suggest waiting 30 seconds or restarting the device before each test measurement to ensure it is not locked to the previous base station. This can happen with some hardware even when the new base station has a better signal level and quality.
You can also conduct performance and speed tests, but keep in mind that the results can vary depending on the current network load. If you cannot measure over time between each test of a new placement, consider this test an indicative measurement value.
Step 4: Test in Different Directions
Once you have identified the nearest base station, you can test aligning the antenna towards that location or those locations, depending on the information provided by your service provider regarding available base stations.
Do not mount the antenna permanently, but connect the device to the antenna connector to perform the test. You may need assistance from another person to avoid climbing. Mount the device with the antenna connected and try temporarily attaching it to a board or pole so that you can test it in different directions without holding it. Remember not to hold the antenna during the measurement, especially if made of metal, as it can give inaccurate results. To compare performance, you need access to the device’s measurement values, accessed through the admin menu or the server the device communicates with, especially if you have a dedicated IoT sensor.
For precision, test at least four, preferably more, directions. Rotate the antenna in equal steps, restart the device (often possible through the web interface of advanced devices), wait for the device to reboot, and measure again. Complete a full rotation and wait for the signal to stabilize at each step. It’s a good idea to note down all the values so you don’t forget them. If the antenna has a narrow opening angle, test as many directions as possible to cover a full rotation and find the best direction. If feasible, test from the highest position where you can mount the antenna.
Step 5: Test Different Frequency Bands
If your device supports it, especially in the case of mobile network routers, lock the device to the frequency or frequencies supported by the operator in your location and repeat the test according to the model described above. You may perform better by testing with different frequency bands than by letting the device select independently.
A Little Tip Along the Way
Network utilization and capacity distribution in public networks are constantly changing. If you experience poor performance after a while, you can repeat the above tests. However, it’s best first to contact your service provider and inquire about any adjustments or changes made to the network (and be prepared to receive only some of the truth). The base station may have been upgraded, new frequencies added, capacity has been reallocated, or there is a temporary service issue with a specific base station.
Running a long antenna cable to place the device as low as possible may be tempting, but I suggest avoiding longer cable lengths. An additional 10 meters of cable will attenuate the signal, but it may be acceptable if it allows for a more suitable mounting position.