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Data Sheet ANT-868-PW-QW
VSWR Graph
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.
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
Reflected Power
3:1
2:1
1:1
25%
11%
0%
868MHz
968MHz
768MHz
1.557
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相关PDF资料
ANT-868-PW-RA
ANT 868MHZ 1/4WAVE SWVL SCREW-MT
ANT-868-WRT-RPS
ANTENNA 868MHZ WRT SERIES RPSMA
ANT-916-CW-HD
ANTENNA 916MHZ 1/4 WAVE WHIP
ANT-916-CW-HWR-RPS
ANTENNA 916MHZ 1/2 WAVE RP/SMA
ANT-916-CW-HW
ANTENNA 916MHZ 1/2 WAVE DIPOLE
ANT-916-CW-QW-SMA
ANTENNA 916MHZ 1/4 WAVE WHIP
ANT-916-CW-RAH
ANTENNA 916MHZ RA 1/4WAVE RPSMA
ANT-916-CW-RCL
ANTENNA 916MHZ RA 1/4 WAVE WHIP
相关代理商/技术参数
ANT-868-PW-QW-UFL
功能描述:868MHz Whip, Straight RF Antenna 750MHz ~ 950MHz 1.6dBi Connector, U.FL Panel Mount 制造商:linx technologies inc. 系列:PW 包装:托盘 零件状态:有效 频率组:UHF（300 MHz ~ 1 GHz） 频率（中心/带）:868MHz 频率范围:750MHz ~ 950MHz 天线类型:鞭状，直形 频带数:1 VSWR:1.9 回波损耗:- 增益:1.6dBi 功率 - 最大值:- 特性:- 端接:连接器，U.FL 侵入防护:- 安装类型:面板安装 高度（最大值）:3.307"（84.00mm） 应用:- 标准包装:50
ANT-868-PW-RA
功能描述:天线 Perm Mnt Swvl Angle 1/4 Wave Whip 868MHz
RoHS:否 制造商:Molex 技术类型:Cellular Antenna 频率: 带宽: 尺寸:106.7 mm L x 13 mm W
ANT-868-RA
制造商:Amphenol Corporation 功能描述:
ANT-868-SP
功能描述:天线 SMD Planar Ant. 868MHz
RoHS:否 制造商:Molex 技术类型:Cellular Antenna 频率: 带宽: 尺寸:106.7 mm L x 13 mm W
ANT-868-SP_
功能描述:ANTENNA 868MHZ PLANAR (SMT) RoHS:是 类别:RF/IF 和 RFID >> RF 天线 系列:SP - Antenna Factor 标准包装:1 系列:*
ANT-868-USP
功能描述:天线 MicroSplatch Planar Antenna 868MHz, SMD
RoHS:否 制造商:Molex 技术类型:Cellular Antenna 频率: 带宽: 尺寸:106.7 mm L x 13 mm W
ANT-868-USP-T
功能描述:MICROSPLATCH ANTENNA, 868MHZ, SM 制造商:linx technologies inc. 系列:- 包装:剪切带（CT） 零件状态:在售 频率组:UHF（300 MHz ~ 1 GHz） 频率（中心/带）:868MHz 天线类型:芯片 频带数:1 VSWR:2 回波损耗:- 增益:0.2dBi 特性:- 端接:焊接 侵入防护:- 安装类型:表面贴装 高度（最大值）:0.100"（2.54mm） 应用:- 标准包装:1
ANT-868-WRT-RPS
功能描述:天线 868MHz Compact Ant. RPSMA Connector
RoHS:否 制造商:Molex 技术类型:Cellular Antenna 频率: 带宽: 尺寸:106.7 mm L x 13 mm W