Apr 28, 2016 at 1:36 PM

矢量

年前教Jackie数学，引进矢量vector概念. 矢量就是有方向性的量度，比如说光的亮度, 声音的高低, 都是没有方向性的. 而速度是有方向性的，不搞清楚速度方向，本来应该朝北走，却向东走，虽然数量一样, 假如每小时30公里，那你可能失之毫厘谬之千里了，永远也达不到目的地. 既然有方向，那就不是简单的数量的加减乘除了. 俩个矢量的加, 尊从余弦定理（The law of cosine). 而最后合成的矢量，很有可能取新的方向，以及不一样的量值. 在物理上，电磁信号是矢量，在空间相遇合成时，要遵循矢量的运算法则. 在场中运动的物体也遵循矢量的运动法则. 更进一步，如果文化也是矢量的话，上次说到不同元素在集里进行组合的时候，会有新的组合可能性. 如果每一个文化元素组合，就会有新的文化矢量，就有新的方向和自有的能量！人和人相遇，也会迸发出新的智慧火花，如果遇见对的人的话。 

Teaching Jackie mathematics two years ago, introducing the vector  concept. Vector is a directional measure. Yet, such as the brightness of light, the level of sound, are not directional. And the speed is directional, if do not figure out the direction of speed, say, originally, I should go north, but go east, although the number is the same, if it is 30 kilometers per hour, then you may lose a thousand miles and never reach your destination. Since there is direction, it is not simply the addition, subtraction, and multiplication of the quantity. The addition of the two vectors, respects the law of cosine. The final synthesized vector is likely to take a new direction and a different magnitude. Physically, electromagnetic signals are vectors. In the case of spatial encounters, the vector algorithm is followed. The objects moving in the field also follow the motion law of the vector. Further, if the culture is also a vector, the last time I mentioned the different elements  combined in the set. At the time, there will be new combinations of possibilities. If every cultural element is combined, there will be new cultural vectors, and there will be new directions and own energy! When people meet, they will also spark new wisdom, if they meet the right person. 

http://www.cnblogs.com/begtostudy/archive/2010/09/04/1817859.html

今天再讲矢量. 天线的电磁辐射覆盖是矢量场. 最简单的天线覆盖pattern 是球形的，omni-direcrion, 有的是中间凹进去, 水平绕一圈甜甜圈型的.  directional-omni, 有的是有方向性的. directional , 像一个圆圆长长的飞艇那样伸出去的. 我们一般无线通讯用的天线覆盖形状, 就是这样的. 想象一下，通讯基站就在三个蜂窝联接的中间，向三个方向发的天线在地上的切面, 就覆盖了那个蜂窝区域！而在天线雷达中, 用到的阵相天线, 也是这个原理. 假设每一个元可以有像飞艇那样的天线覆盖形状pattern. 因为他们是矢量，而且有相位差，表示他们各自的强度,方向性不同. 按照我昨天说的矢量加法，当整个阵面的所有的小天线覆盖形状，进行矢量和的时候，以精确的设计，最后的主覆盖形状也可以有像飞艇那样的形状，并指向你设计的上下左右方向. 

Let's talk about vectors today. The electromagnetic radiation coverage of the antenna is a vector field. The simplest antenna coverage pattern is spherical, omni-direcrion, and some are recessed in the middle, horizontally wrapped around like a dough-nut type. Ddirectional-omni, some have direction. Directional. Like a round long airship. Our general antenna coverage for wireless communication is like this.Imagine that the communication base station is in the middle of the three cellular connections, and the antenna in the three directions on the ground, cuts the honeycomb area! In the antenna radar, the array antenna used is also this principle. It is assumed that each element can have an antenna cover shape pattern like an airship. Because they are vectors and have phase differences, they indicate their respective strength and different directionality.  According to the vector addition I said yesterday, when all the small antennas of the entire array cover the shape and carry out the vector sum, with the precise design, the final main cover shape can also have the shape like an airship and point to your designed, up and down and left and right directions.

比如当花瓣一样四周分布的天线形状，当他们最终合在一起时，覆盖形状可能是从花蕊中心伸出的一个主体的, 更大的飞艇状的pattern. 有的阵相天线有三个面，或四个面，尽可能地覆盖完整的空间. 而如果阵相天线可以旋转，那所包含的范围就更远, 更大. 因为相阵元素多，场的能量叠加起来就会大，表示能够探测的距离范围就很远. 这是军事上的需要！一般来说, 无线通讯的覆盖最远可到20英里，军用雷达天线可以有几百英里，对于更遥远的，波长更短，信号更弱的卫星信号，因为远，所以卫星天线就象收集光信号的凹镜. 当然卫星天线的宽度，曲面是和卫星信号的频道有关的. 声纳，因为在水里没法传播电磁波，设计的原理和雷达天线是一样的. 所谓被动雷达，是纯接收的. 主动雷达，就是先放出一个信号，再有意地的收集回波，哪个方向有回波，就表示有目标出现了.

For example, when the petals are distributed around the shape of the antenna, when they finally come together, the cover shape may be a main body extending from the center of the flower, a larger airship-like pattern. Some array antennas have three faces, or  four faces covering the complete space as much as possible. If the array antenna can be rotated, the range contained is farther and larger. Because there are many phase elements, the energy of the field will be superimposed, indicating that it can detect  very far distance. This is a military need! In general, wireless communication covers up to 20 miles, military radar antennas can have hundreds of miles, and for more distant, shorter wavelength. Weaker satellite signals, because far away, satellite antennas are like collecting light wave, so the concave mirror of the signal, of course, the width of the satellite antenna is large, the surface is related to the frequency of the satellite signal. Sonar, because the electromagnetic wave can not be transmitted in the water, the design principle is the same as the radar antenna. The so-called passive radar is pure reception. Active radar is to first release a signal, and then intentionally collect echoes. Which direction has echoes, it means that there are targets.

http://www.antenna-theory.com/cn/basics/radPattern.php

http://wapbaike.baidu.com/view/184371.htm?adapt=1&

http://www.360doc.cn/article/225291_203396010.html

http://www.baike.com/ipadwiki/%E6%8B%96%E6%9B%B3%E9%98%B5%E5%88%97%E5%A3%B0%E7%BA%B3