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In the 850 and 1900 MHz cellular bands, the reflections and scattering effects are somewhat less but the same principles apply. A typical cellular band wireless link has many reflections and significant scattering and is virtually never LOS. Therefore, antenna polarization is of little concern. Additionally, a handheld mobile device can be used in many orientations, so optimizing the radiation pattern shape is not useful. For devices that are in a fixed location, some design and optimization of the radiation pattern should be considered in a limited way. For example, a wireless device in a wall-mounted electric meter should waste as little energy as possible directly up or down or in the direction of the building.

3.4 Antenna Selection and Implementation

A typical wireless device, like a handset or a laptop wireless modem, has an electrically small ground plane in the 850 and 1900 MHz frequency bands. Because of this, the antenna(s) will interact substantially with the entire device. In fact, the more efficient an antenna is, the more it will interact with the local ground plane high efficiency, by design, implies interaction. Commercial antenna products may

Antenna Fundamentals Technical Brief

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