ANT-916-PW-RA Data Sheet by Product Description 7.0 mm The RA Series offers maximum mounting and (0.28 ) orientation flexibility in a cost-effective reduced-height package. The antennas innovative articulating base allows it to tilt and rotate for optimum orientation. The RA mounts to a PCB via a single screw and meets Part 15 requirements. 68.5 mm (2.70 ) Features Low cost 9.5 mm Reduced-height helical whip (0.37 ) Tilts and rotates 5.5 mm Excellent performance (0.22 ) Omni-directional pattern Screw-mount 21.0 mm 30.5 mm (0.83 ) (1.20 ) Use with plastic* or metal enclosures * Requires proximity ground plane 2.0 mm Electrical Specifications (0.08 ) Center frequency: 916Hz 6/32 8.0 mm Bandwidth: 8161095MHz UNC (0.31 ) Wavelength: -wave VSWR: 1.9 typical at center Peak Gain: 0.0dBi 5.5 mm 4.0 mm (0.22 ) (0.16 ) Impedance: 50-ohms Connection: Screw-mount Oper. Temp. Range: 20C to +60C Recommended Footprint Electrical specifications and plots measured on 6.35 cm x 10.16 cm (2.5 x 4 ) reference ground plane 11.18 mm (0.440 ) Ordering Information ANT-916-PW-RA 8.0 mm (0.315 ) 4.0 mm (0.157 ) 5.9 mm 3.81 mm (0.220 ) (0.150 ) 1 Revised 12/11/13Counterpoise Quarter-wave or monopole antennas require an associated ground plane counterpoise for proper operation. The size and location of the ground plane relative to the antenna will affect the overall performance of the antenna in the final design. When used in conjunction with a ground plane smaller than that used to tune the antenna, the center frequency typically will shift higher in frequency and the bandwidth will decrease. The proximity of other circuit elements and packaging near the antenna will also affect the final performance. For further discussion and guidance on the importance of the ground plane counterpoise, please refer to Linx Application Note AN-00501: Understanding Antenna Specifications and Operation. VSWR Graph VSWR 1.917 Reflected Power 3:1 25% 2:1 11% 1:1 0% 816MHz 916MHz 1016MHz What is VSWR The Voltage Standing Wave Ratio (VSWR) is a measurement of how well an antenna is matched to a source impedance, typically 50-ohms. It is calculated by measuring the voltage wave that is headed toward the load versus the voltage wave that is reflected back from the load. A perfect match will have a VSWR of 1:1. The higher the first number, the worse the match, and the more inefficient the system. Since a perfect match cannot ever be obtained, some benchmark for performance needs to be set. In the case of antenna VSWR, this is usually 2:1. At this point, 88.9% of the energy sent to the antenna by the transmitter is radiated into free space and 11.1% is either reflected back into the source or lost as heat on the structure of the antenna. In the other direction, 88.9% of the energy recovered by the antenna is transferred into the receiver. As a side note, since the :1 is always implied, many data sheets will remove it and just display the first number. How to Read a VSWR Graph VSWR is usually displayed graphically versus frequency. The lowest point on the graph is the antennas operational center frequency. In most cases, this will be different than the designed center frequency due to fabrication tolerances. The VSWR at that point denotes how close to 50-ohms the antenna gets. Linx specifies the recommended bandwidth as the range where the typical antenna VSWR is less than 2:1. Data Sheet ANT-916-PW-RA 2 by