AN4190

Antennas for low power applications

Doc ID 023812 Rev 1

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Figure 18.

5.8 GHz patch antenna implementation and characteristics

2.3

Ceramic antenna

The latest entry into the antenna field is the ceramic (chip) antenna. They are surface mount

devices made of ceramic material. There are several types of ceramic antennas, each with

their own characteristics.

Ceramic antennas offer some advantages: they are separate components, have small sizes

and a variety of configurations are available, close proximity to other components doesn't

cause as severe a detuning as with trace antennas, they are less affected by environmental

factors or human operators than trace antennas, flexible tuning and testing options are

possible, and design changes are more easily introduced.

Some disadvantages are also present: the initial cost of the antenna plus logistics can be

higher than the cost of others types of antennas, some level of RF expertise is needed for

optimal implementation.

Ceramic antennas can be designed in both on-ground and off-ground styles, with on-ground

antennas being somewhat taller. The optimal ceramic material composition for the antenna

and the electrical specifications selected usually depend on the intended frequency, with an

effect on the dimension. Also ceramic antennas can use matching circuits, optional ground

clear areas, or a trace for coarse tuning, depending on the application.

This type of antenna can be adapted to small boards and offers flexibility for unique design

layouts. The reliability and interference problems associated with being in close proximity to

other components or people are greatly reduced with ceramic antennas. Incorporating a

separate antenna offers the option of utilizing the full available height of the device, making it

possible to have a 3D structure with a smaller PCB area.

An example of a ceramic antenna is shown in Figure 19.

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