PORTLAND, Ore. Wireless applications in the 2.4-GHz band—from remote controls to Zigbee industrial controllers to Wi-Fi nodes—usually have to add a more powerful amplifier to extend their range. But now Texas Instrument Inc. has a better idea: just replace the traditional metal antenna with a resonant slot on the printed-circuit board.
Next week, TI will announce it has adopted Pinyon Technology Inc.'s Airwire slot antenna for its RF reference designs—disclosing schematics to its OEMs that TI says nearly double of the range of its RF front-end chips.
"What's nice about the Pinyon Airwire antenna is that you can almost double your range for the same output power," said Richard Wallace, the RF applications engineer in charge of updating TI's free online reference designs for its RF front-end chip sets.
"Or if you don't need extended range—for instance, if your application is a remote control—then switching to Pinyon's antenna will allow you to use only about half the power you need with a traditional antenna which will extend the battery life."
Pinyon's slot antenna design was an "accidental" invention of Pinyon, which discovered through experimentation that a resonant slot in a copper-clad printed-circuit board could boost the range of an antenna. The technique works by matching the length of the slot to the RF wavelength, then shorting it out across the middle with a small microstrip—an electrical transmission line consisting of a conducting strip separated from the ground plane by a dielectric.
The resistance of the embedded microstrip converts the voltages detected on the antenna into a current that drives the RF front-end chip. This, according to TI, nearly doubles the range of the antenna or allows it to hold the range constant with about half the power. The icing on the cake is cost—about a 25 cents for the printed-circuit board material plus a few resistors, diodes and capacitors.
TI's first reference design will be for its and CC2430 and CC2510 front-end chips. The CC2510 in laboratory testing has a range of about 460 feet with a traditional antenna. However, by merely etching the antenna into a circuit board, following TI's schematics, the CC2510's range can be extended to over 880 feet. "We have created reference designs which include the Pinyon antenna as a part of its circuit board," said Wallace. "We have fully characterized this design so that now anybody using our RF chips can build-in their own slot-antenna."
TI plans to continue to roll out reference designs for its other RF front-end chip sets, including its newest range-boosting chip, the CC2591 power amplifier, whose range can be almost doubled from about 2.5- to almost 5-miles, just by switching to the Pinyon antenna, according to the company.