Antennas for Embedded Applications

 

We see lot of wireless applications in the market and especially the wireless in IoT applications. IoT can be in commercial, industrial. The current wireless applications for example include Bluetooth, Wi-FI, GPS, 4G, 5G, LoRA, UHF. The major challenge in IoT application is the antenna. Selecting the right antenna for a right application is a major challenge for the designer. Antenna can be external or on-board antenna. External antenna meant we provide connector on the PCB and antenna is plugged in. This provides advantages of good gain and range. With the on-board antenna, the options are limited and we have two of them - one can be PCB trace antenna in which PCB trace is etched on top of the PCB like any other copper trace and second one is Chip antenna which is soldered on the PCB like any other component. Let us look at the advantages and disadvantages of both of them. Remember that chip antennas are ceramic type.

Before moving further on the antenna topic, one has to remember that selecting an antenna is dependent on the frequency of operation and the size of the antenna is related to it.

Johanson is one of the antenna vendors for these IoT applications and they have a selection criteria listed in the below link:

https://www.johansontechnology.com/chip-antenna-selection

Following parameters are important while selecting antenna for your application:

• Antenna type
• Frequency of operation (bandwidth, bands supported)
• Gain
• VSWR
• Directional/Omni
• Impedance of antenna (where the chip output/matching connects the antenna, called the feed point)
• Polarization
• Efficiency (%) - we get this from the datasheet for most of the antennas
• Size of the antenna and mounting requirements
• Matching Requirements

The matching plays a crucial role and is always included in the design after performing simulations and these matching values always need to be tuned when actual PCB comes in hand.