What Makes a Good Antenna?

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What Makes a Good Antenna?

The antenna and its mounting are a critical part of any wireless system. The ability to launch or receive electromagnetic energy into free space efficiently, results in increased range, signal quality and battery life improvements.

An antenna can be considered to be both an impedance matcher and a filter. It must match the impedance of the RF circuit to that of free space and will have an operating frequency range by design.

Impedance matching is important, but does not describe how efficient the antenna will be at radiating or receiving electromagnetic energy. A resistive load could provide a good match, but will be a poor radiator. A perfect transmitting antenna will radiate all of the power delivered to it into space. A practical antenna will be a combination of both.

The variables involved in providing this balance creates a dynamic situation that can only be realistically assessed by Over-The-Air (OTA) measurement of transmit and receive performance of the device including its antenna. For a portable or mobile device it’s important to obtain a three dimensional antenna characterisation to determine how the device will perform when in use.

Direct measurement of the far field characteristics requires very large test facilities due to the range distances involved. However, modern antenna performance measurements make use of techniques that reconstruct the far field by making multiple measurements around the radiating element in a relatively compact chamber. These systems provide 3D transmit antenna plots in a matter of minutes, making the evaluation of antenna performance quick and easy.

In order to be successful in a competitive market, wireless device manufacturers must provide users with a product which has a reliable and adequate level of radio performance. An OTA evaluation of radiated performance is one way to achieve that.

For more information, visit our OTA Services pages.

source: http://europe-ul.com/ctech/what-makes-a-good-antenna/

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