Obtaining an intuitive idea for why antennas radiate is helpful in understanding the fundamentals of antennas. On this page, I'll attempt to give a low-key explanation with no regard to mathematics on how and why antennas radiate electromagnetic fiel…
AT3912 Antennas on Tree %%zzt 只能考虑性质了. 把最后选择的k个点的连通块求出来,连通块内部的点表示都是互异的 连通块外部的点只能形成若干条链,并且这k个点的每一个最多与一个外部点相连. 直接从每个叶子往上跳,当fa[x]度数>2的时停下 如果fa[x]之前没有链,那么可以先省下一次,否则就要把x变成k个点之一 #include<bits/stdc++.h> #define reg register int #define il inline #define…
题意: 在一个 n x n 的平面上,给定 m 个等腰直角三角形(各点均为整数),问该平面上被三角形覆盖奇数次的点有多少个. 思路: 由于 n 较大,不能模拟解决,故使用离散化思想. 考虑每一行有多少点被覆盖了奇数次,题目从二维转换成一维. 对于每一行,考虑每个三角形在此行覆盖的线段,记录下每条线段的左端点 l .右端点 r 保存在同一个数组中. 排序后则容易知道第一个到第二个数.第三到第四个数...的部分是覆盖奇数次,以此累加结果. 代码: #include<iostream> #inclu…
Radio Basics for RFID The following is excerpted from Chapter 3: Radio Basics for UHF RFID from the Book, The RF in RFID: Passive UHF RFID in Practice by Daniel M. Dobkin. Order a copy of The RF in RFID: Passive UHF RFID in Practice before December 3…
Reference : 1. wikipedia The dipole antenna is the simplest and most widely used class of antenna.It consists of two identical conductive elements such as metal wires or rods, which are usually bilaterally symmetrical.Each side of the feedline to the…
The inverted-F antenna is shown in Figure 1. While this antenna appears to be a wire antenna, after some analysis of how this antenna radiates, it is more accurately classified as an aperture(孔) antenna. Figure1. Geometry of Inverted-F Antenna The fe…
QUICK START GUIDE This page is a guide aimed at helping anyone set up a cheap radio scanner based on the RTL-SDR software defined radio as fast as possible on a Windows system. If you have any trouble during the installation, please see the troublesh…
Sound card based RFID sniffer/emulator (Too tired after recon.cx to do draw the schematics better than that :) Stay tuned for the next version including Tag emulation.) baudline FFT signal analyzer for sniffing LF RFID tags using our sound card based…
链接. General Books on Electromagnetics When our department recently reviewed our junior-level text, we were struck by the large number of books now available from wh ich to teach introductory electromagnetics. Here, I mention only my two personal favo…
Coax Transformers How to determine the needed Z for a wanted Quarter Wave Lines tranformation ratio Some applied examples 1. From 50 ohms feedline to 12.5 ohms Yagi with straight split DE? Z = sqrt ( 50 ohms x 12.5 ohms) = 25 ohms This we can produce…
Antenna Placement Time Limit: 1000MS Memory Limit: 65536K Total Submissions: 7788 Accepted: 3880 Description The Global Aerial Research Centre has been allotted the task of building the fifth generation of mobile phone nets in Sweden. The most st…
Antenna Placement Time Limit: 1000MS Memory Limit: 65536K Total Submissions: 5645 Accepted: 2825 Description The Global Aerial Research Centre has been allotted the task of building the fifth generation of mobile phone nets in Sweden. The most striki…
Antenna Placement Time Limit: 1000MS Memory Limit: 65536K Total Submissions: 6991 Accepted: 3466 Description The Global Aerial Research Centre has been allotted the task of building the fifth generation of mobile phone nets in Sweden. The most st…
Antenna Placement Time Limit: 1000MS Memory Limit: 65536K Total Submissions: 7329 Accepted: 3635 Description The Global Aerial Research Centre has been allotted the task of building the fifth generation of mobile phone nets in Sweden. The most st…
Antenna Placement Time Limit: 1000MS Memory Limit: 65536K Total Submissions: 7574 Accepted: 3762 Description The Global Aerial Research Centre has been allotted the task of building the fifth generation of mobile phone nets in Sweden. The most striki…
Security Checklist Website by Michael Horowitz Home | Introduction | Router Bugs | Security Checklist | Tests | Resources | About | The most expert person in the world can only make a router as secure as the firmware (router OS) allows. The foll…
NFC for Business What is the NFC Forum? The NFC Forum is a not-for-profit industry organization whose mission is to advance the use of Near Field Communication technology by developing specifications, ensuring interoperability among devices and servi…
Antenna Placement DescriptionThe Global Aerial Research Centre has been allotted the task of building the fifth generation of mobile phone nets in Sweden. The most striking reason why they got the job, is their discovery of a new, highly noise resist…
1.https://www.pjrc.com/teensy/td_libs_VirtualWire.html These modules worked very reliably when sitting only close to each other on a table. When separated by about 20 feet with ordinary office furniture, and a 13 cm wire attached to each (in the midd…
http://poj.org/problem?id=3020 Antenna Placement Time Limit: 1000MS Memory Limit: 65536K Total Submissions: 7565 Accepted: 3758 Description The Global Aerial Research Centre has been allotted the task of building the fifth generation of mobile ph…
Got a tough RF environment? Turn to TI’s proven LF technology TI’s low-frequency (LF) technology has been solving tough RF challenges for more than 20 years. Got a dirty, wet, noisy, hot or cold environment that has to withstand extreme shock or vibr…
This 125 kHz RFID reader http://www.serasidis.gr/circuits/RFID_reader/125kHz_RFID_reader.htm http://www.serasidis.gr/circuits/RFID_reader/images/125kHz_RFID_reader_schem.GIF I will try to explain with simple words how the RFID works. The ATtiny13 use…
Passive RFID Basics - AN680 INTRODUCTION Radio Frequency Identification (RFID) systems use radio frequency to identify, locate and track people, assets and animals. Passive RFID systems are composed of three components – a reader (interrogator), pass…
