ANT-868-CW-HW Data Sheet by Product Description 8.1 mm HW Series -wave center-fed dipole antennas (0.32 ) deliver outstanding performance in a rugged and cosmetically attractive package. The antenna contains a helical element and internal counterpoise which eliminates external ground plane dependence and maximizes performance. HW Series antennas attach via a standard SMA or Part 15 compliant RP-SMA connector. Custom colors and connectors are available for volume OEM customers. Features Low cost Internal counterpoise Excellent performance 135.5 mm Omni-directional pattern (5.33 ) Outstanding VSWR Rugged & damage-resistant 10.7 mm Standard SMA or Part 15 compliant RP-SMA (0.42 ) connector Internal O-ring seal on connector End View Electrical Specifications Center Frequency: 868MHz 5.6 mm (0.22 ) Recmd. Freq. Range: 855880MHz Wavelength: -wave 15.5 mm (0.61 ) VSWR: 2.0 typical at center Peak Gain: 0dBi Impedance: 50-ohms Connection: SMA or RP-SMA Oper. Temp. Range: 20C to +85C Electrical specifications and plots measured with a 10.16 cm x 10.16 cm (4.00 x 4.00 ) reference ground plane. Ordering Information ANT-868-CW-HW (with RP-SMA connector) ANT-868-CW-HW-SMA (with SMA connector) 1 Revised 11/18/13VSWR Graph VSWR 1.517 Reflected Power 3:1 25% 2:1 11% 1:1 0% 818MHz 868MHz 918MHz 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. 159 Ort Lane, Merlin, OR, US 97532 Phone: +1 541 471 6256 Data Sheet ANT-868-CW-HW 2 Fax: +1 541 471 6251 by www.linxtechnologies.com