ANT-315-SP

ANT-315-SP Data Sheet by Product Description The Splatch uses a grounded-line technique to achieve outstanding performance from a tiny surface-mount element. This unique antenna is designed for hand or reflow-mounting directly to a product’s circuit board. Its low cost makes it ideal for volume applications. Unlike many compact antennas, the Splatch exhibits good proximity performance, making it an appropriate choice for handheld applications such as remote controls, pagers and alert devices. 27.94 mm (1.10") 13.7 mm (0.54") 1.5 mm (0.06") Features • • • • • • • 1.27 mm (0.05") Recommended Footprint Very low cost Ultra-compact package Direct PCB attachment Ideal for concealed / internal mounting Perfect for compact portable devices Suitable for hand or reflow-assembly Resistant to proximity effects 5.1 mm (0.20") 2.54 mm (0.10") 2.03 mm (0.08") Recommended Mounting Electrical Specifications Center Frequency: Recom. Freq. Range: Bandwidth: Wavelength: VSWR: Impedance: Connection: Oper. Temp. Range: 5.1 mm (0.20") 38.86 mm (1.53 in) 315MHz 312–317MHz 5MHz ¼-wave ≤ 1.9 typ. at center 50-ohms Surface-mount –40°C to +130°C 6.32 mm (0.25 in) 15.48 mm (0.57 in) No ground plane or traces under the antenna PCB pads for the Splatch Vias to ground plane Ground plane on bottom layer for counterpoise 50-ohm microstrip line Electrical specifications and plots measured on 3.8 cm x 8.4 cm (1.50” x 3.30”) reference ground plane. 98.55 mm (3.88 in) Ordering Information 83.57 mm (3.29 in) ANT-315-SP (supplied in tubes of 20 pieces) ANT-315-SP-T (Tape and reel of 500 pieces) 0.51 mm (0.02 in) 37.85 mm (1.49 in) 0.51 mm (0.02 in) Please see AN-00502 for more details on PCB layout. –1– Revised 1/3/2017 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 3:1 1.558 Reflected Power 25% 11% 2:1 1:1 277.5MHz 315MHz 0% 352.5MHz 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 has 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 is 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. Copyright © 2017 Linx Technologies 159 Ort Lane, Merlin, OR 97532 Phone: +1 541 471 6256 Fax: +1 541 471 6251 www.linxtechnologies.com –2– ANT-315-SP Data Sheet by