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What Criteria Should Be Considered When Evaluating Cellular Antennas?

The right antenna can make or break a design, but a poor choice can result in less-than-ideal communication. The primary considerations for the selection process are the focus of this article. Form factor for both internal and external devices are considered, as well as other important factors such as frequency response, gain, impedance matching, directional characteristics and polarization.

The final application should continue to be the major factor in the evaluation. You can always use Siretta's antenna selection tool to assist you to find the best answer.

Whether the final product is intended to be fixed or mobile is a key deciding factor in the choosing process. If the device has a fixed application and a strong signal, you might be lucky. However, if your mobile device is in a weak signal area or is frequently exposed to bad weather, the evaluation process is essential, and product choice is crucial to the success of your final product.

Types of antennas

The application and product design will, in part, decide the form factor (physical form) of the antenna. Siretta provides a comprehensive range of mounting style solutions, including adhesive, through-hole, direct, embedded, magnetic, wall, and pole mount options available.

However, permanent equipment offers the chance to choose from a wider antenna range where size and orientation are less important. For many mobile devices, the "smaller the better" attitude is frequently the major factor, driving the antenna selection towards embedded solutions.

There are also extra factors to consider, despite the greater selection choices provided by fixed locations. Yagi antenna designs with direct line of sight to a provider's antenna tower will be best suited for remote permanent installations with direct access to open space, such as remote water pumping stations or storage depots.

antenna signal maps

By using numerous elements in the antenna construction to limit the beam and offer gain in one direction, directional antennas aligned with the closest cell tower increase signal strength.

Higher gain omnidirectional antenna designs that can interact with numerous cell masts on buildings are more likely to be advantageous for other fixed locations, particularly those found in cities and urban environments.

The required frequency bands are the focus of the next set of selection criteria; traditionally, this was a simpler process because older cellular equipment had fewer frequency bands. The need for multiband and MIMO (Multiple Input, Multiple Output) antennas for a single device has skyrocketed with the introduction of 4G (LTE) and 5G (LTE). By capturing energy from various wave pathways, more antennas strengthen the signal. Global compatibility is available for 2G and 3G applications, but 4G/5G NR has increased complexity due to larger data rates and smaller cells, necessitating the use of more frequency bands. Currently, there are about 70 frequency bands.

The choice of frequency or band is also influenced by the location and carriers that are present in the local region. Verizon, Sprint, and China Telecom, for instance, will use different bands and frequencies than Vodafone. Even the widest band antenna is unlikely to be able to cover all 70 frequency bands, and even if they can, performance will vary across them. This is vital to keep in mind when choosing an antenna.

Antenna matching is the design factor to be considered after the equipment and carrier have been chosen. By eliminating mismatched impedance and reduced voltage standing wave ratio (VSWR) losses, a perfectly matched antenna can improve performance.

The antenna's impedance, which is normally set to 50 Ohms, is a complicated circuit comprising capacitance, inductance, and resistance that transforms into a tuned circuit when connected to a transmitter or receiver.

It is crucial to match the antenna choice with the output impedance specified by the manufacturer for cellular devices. However, a matching circuit with a combination of capacitance, resistance, and inductance will be needed if you're creating an embedded antenna with a PCB modem.

It is therefore a balance that achieves a compromise and an overall level of performance acceptable to the needs of the device receiver. The intended frequency or band will have different criteria to obtain a perfect match, so it is important to strike this balance.

range of removable antennas

Antennas can broadcast the signal in a variety of configurations and directions, either in a linear or circular fashion. Linear Polarization is the ability of linear signals to travel in either the horizontal or vertical plane or some angle in between. Circular Polarization (CP) can work in two ways, either Right Hand (RHCP), or Left Hand (LHCP), where waveforms effectively spin in both horizontal and vertical planes rotating in time. RHCP waveforms spin in the opposite direction to LHCP waveforms. Circular Polarization is beneficial when the target has a linear antenna which is mobile and therefore regularly on the move and susceptible to reflections. This would be quite challenging if trying to work in this same application with linear antennas at both ends. It is important to carefully examine the wave's direction and propagation away from the antenna. If done correctly, it will maximise the antenna's effectiveness; but, if done wrong, it can significantly lower the signal intensity by up to 20dB.

Finally, selecting the right antenna will raise the dependability and efficiency of any radio device. In industrial modems, the manufacturer mostly determines the option and style, which is detailed in the datasheet. Directional antennas will unquestionably be useful in isolated areas with poor transmissions. With PCB style antennas in particular, the option is much more complicated for embedded devices.

From embedded PCB designs to high-gain directional pole-mounted Yagi types, Siretta offers a wide variety of antennas. As a top producer and developer of Internet of Things (IoT) goods, services, and software, Siretta specialise in offering these for industrial markets and business-to-business applications. With a focus on cellular technologies supporting 2G (GPRS), 3G (UMTS), 4G (LTE Cat 1), 4G (LTE Cat 4), LTE Cat NB-IoT, LTE Category M & 5G, Siretta has a wealth of knowledge and experience in the IoT space. Cellular modems and terminals, routers, cellular network analyzers, RF antennas, RF adapters, and low-loss RF cables are among the available products.

To assist you with your antenna selection, look at our Antenna Selector Tool

Siretta are a leading developer and manufacturer of Industrial IoT products, software and solutions. We have extensive knowledge and experience within IoT with a focus on cellular technologies in support of 2G (GPRS), 3G (UMTS), 4G (LTE), NB-IoT and LTE Category M as well as the emerging 5G.
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