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TI 藍牙天線設計,很全，英文版。
Any structure that is resonant at 2.45 GHz with bandwidth more than 100 MHz and efficiency >50% can
be considered a Bluetooth antenna. Therefore, a countless variety of antennas can be used, and they are
application-specific. Some common types are:
• Wire Monopole — This consists of a simple wire soldered at one end from which it is fed against a
ground plane. It is trimmed to be resonant at 2.45 GHz and provides good performance and high
efficiency. The disadvantage of this antenna is that it is not low profile because it projects above the
PCB.
• PIFA — The Printed Inverted F Antenna is like a monopole printed on a PCB, but it has a ground point
and feed point along the main resonant structure.
• Helix — Similar to the wire monopole, except that it is coiled around a central core (usually air) making
the physical dimensions smaller. It provides excellent performance, but projects above the PCB.
• Ceramic — Surface mount dielectric antennas are the smallest types of antennas available, because
they are printed on a high-dk ceramic slab, which makes the electric field concentrated allowing the
antenna to be made small while keeping a high resonant frequency.
This application note only describes PIFA and ceramic antennas because they are the most common, lowprofile,
smallest, and inexpensive types available.
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