ANT-315-CW-HD

ANT-315-CW-HD Data Sheet by Product Description This reduced-height ¼-wave antenna is ready for years of use thanks to a flexible internal helical that is over-molded with a heavy-duty protective jacket. It’s an excellent choice for outdoor applications or for use in adverse environments where the antenna must resist shock, harsh weather and tampering. HD Series antennas attach via an FCC Part 15 compliant RP-SMA connector. 12.3 mm (0.48") 13.5 mm (0.53") 10.5 mm (0.41") Features • • • • • • • • • • Reduced-height helical whip Excellent performance Omni-directional pattern Very low VSWR Heavy-duty construction Damage-resistant Fully weatherized Flexible main shaft Part 15 compliant RP-SMA connector Use with plastic* or metal enclosures 117.0 mm (4.61”) 45.0 mm (1.77") * Requires proximity ground plane Electrical Specifications Center Frequency: Recom. Freq. Range: Wavelength: VSWR: Impedance: Connection: Oper. Temp. Range: 315MHz 310–320MHz ¼-wave ≤ 2.0 typical at center 50-ohms RP-SMA –30°C to +70°C 6.0 mm (0.24”) 13.5 mm (0.53”) Electrical specifications and plots measured on a 10.16 cm x 10.16 cm (4.00" x 4.00") reference ground plane End View Ordering Information 6.4 mm (0.25”) ANT-315-CW-HD –1– Revised 4/14/14 Counterpoise 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 Reflected Power 1.827 3:1 25% 2:1 11% 1:1 240MHz 0% 390MHz 315MHz 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 antenna’s 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 Fax: +1 541 471 6251 www.linxtechnologies.com –2– Data Sheet ANT-315-CW-HD by