Academy for LoRaWAN®

The design of the antenna is one of the most important aspects of wireless communication, and yet it is often left to the end.  The Linx Technologies’ Application Note AN-00501: Understanding Antenna Specifications and Operation provides an excellent explanation of the importance of antenna design and operation.

Read the Application Note

(Reading time: 30 min)

SOURCE: Linx Technologies: Application Note AN-00501--Understanding Antenna Specifications and Operation

Key takeaways

• An antenna is a device that converts electric currents into electromagnetic waves and vice versa.
• The frequency of the electromagnetic waves is related to the wavelength by the following equation: λ = C / f where λ is the wavelength, C is the speed of light (c = approx.  3x10⁸ m/s) and f is the frequency.
• Reducing the antenna’s size will have some impact on the efficiency and impedance of the antenna, which can affect the final performance of the system.
• A half-wave dipole antenna has a length that is one-half of the fundamental wavelength. It is broken into two quarter-wave lengths called elements.
• A quarter-wave monopole antenna is the most common antenna on today’s portable devices. The ground plane on the product’s printed circuit board (PCB) serves as a counterpoise. This way, the size of the antenna needs to be a quarter of the wavelength.
• Another way to reduce the size of the antenna is to coil the element. This is where a straight wire is coiled, or wrapped, around a non-conductive substrate to create what is called a helical element.
• A quarter of the wavelength of the 868MHz frequency is 8.2cm (3.23in.). For the 915MHz frequency, this is 7.8cm (2,87in).