FYP 1: history of antenna

First of all, some introduction to the antenna is great need since I don't really have the basic. I think my lecturer  was lounging at me every time when I asked some related questions even though he did not express out. However, this is really not our fault. We have only learned antenna through the laboratory, not the proper lecture. Hence, it's not surprising that I am so noob.

Well, let start my FYP project.

History of the antenna: Hertz and Marconi invented. Antenna seem to have a bewildering 使人困惑 的, but all operate according to same basic principle of EM.

Antennas are our eye and ear on the world. They are links with space. They are essential基本的, integral part of our civilization. Antenna has been around for long time, millions of years, as the organ for touch or feeling of animals, birds, and insects. Last 100 years, acquired a new significance as the connecting link between a radio system and the outside world.

1^st   antenna built by Heinrich Hertz. In 1886, he assembles apparatus we would now describe as a complete radio system operating at meter wavelengths with an end-loaded dipole as the transmitting antenna and a resonant square-loop antenna as receiver.

Receiver: resonant square-loop antenna; transmitting: end-loaded dipole.

His invention remained a laboratory curiosity until 20 years old Guglielmo Marconi went to add tuning circuits, big antenna and ground systems for longer wavelengths, and was able to signal over long distances. In mid –December 1901, he startled the world by receiving signals at St.Johmx, Newfoundland from a transmitting station he had constructed at Poldhu in Cornwall, England. A year later, he began regular transatlantic message service in spite of a suit诉求 by the Cable Company for infringing侵害 on its monopoly of transatlantic messaging.

With the advent of the radar after World War II, centimeter wavelength became popular and the entire radio spectrum opened to wide usage. Our probes 探查with their array一系列 of antennas have visited the planets of the solar system and beyond, responding to our commands and sending back photographer and data at centimeter wavelengths even though it may take over 5 hours for the signal to travel one way. And our radio telescope antenna operate at millimeter to kilometer wavelengths receive signal from object to distant that it has taken more than 10 billion years for the signal to arrive.

After Heinrich Hertz 1^st demonstrated radiation from antenna, it was called wireless. And wireless it was until broadcasting began about 1920 and the word radio was introduced. Now wireless s back to describe the many systems that operate without wires as distinguished from radio, which to most persons now implies AM or FM.

Dimensions规格 and Unit

Dimension defines some physical characteristic such as length, mass, time, velocity and force.

Fundamental 6 dimension: length, time, mass, luminous intensity, electric current, temperature.

Secondary dimension: other dimension

Unit: standard/ reference by which the dimension can expressed numerical. For eg, the length (dimension) of a steel rod might be 2 meters, and its mass (dimension) 5 kilograms.

Fundamental and Secondary Unit

Fundamental/base unit: Unit for fundamental dimension. SI unit (International System of units, SI unit are used. The six fundamental units are meter, second, kilograms, candela, ampere, Kelvin

The unit for other dimensions are called secondary or derived units and based on these fundamental units.

   

Reference: Antenna for All Aplications third edition (John D.Kraus & Ronald J. Marhefka)

韩文（三）

韩文的母音很奇怪，还有double的。
以下就是double vowel
ㅐ ae（嘴形长一点）
ㅔ e  （发音是a,但是短的发音：edisi）
ㅒ ye（发音：ye）  
ㅖ ye（发音：ye）
ㅘ wa
ㅝ wo
ㅙ wae（发音：where 第二声，上喉发音）
ㅞ we（发音：where 第二声，较短，下喉发音）
ㅟ wi（发音：wi）
ㅢ eui（发音：很快的eu+i）
ㅚ we（发音：也是where）


目前，还是背不到double vowel。
而母音有double,子音当然也有double。
ㄲ      kak（没有吐气）
ㅃ      ba（第四声） 
ㅉ      ja （第四声）
ㄸ      da（第四声）  
ㅆ      sa（第四声）

之前也提过了，韩文字是由vowel + consonant 组成的。因此double vowel的韩文字是：
애（ae）、에（e）、얘（ye）、예（ye）……

那么，学了double vowel 和double consonant 后，就来学写自己的名字吧。需要注意的是，韩文字是依据发音拼写的，因此可能会和英文字母有出入。

例子：
kajang（카장）或（까 장）都行。
lim man chew（림먼주lim man jeo）

我的名字：
lim man shi （림먼리）

话说，在课堂上写自己的名字时，闹了笑话，被老师笑说自创了文字。
原因是我的名字里，shi "h"在韩文里是没有发音的（下次解释为何没发音），但是我不知道，结果把名字写成（ㄹ히），让老师特地在前面跟大家说。

练习其他人的名字
其他人的名字：
lim man ping （림먼펭）
lim man ching（림먼칭）
lai jin hui （라이진후이）

挺好玩的。

韩文比较麻烦的地方是它的读音，需根剧规则来发音。因此，之前认为只要懂得读音就会写韩文不太正确，因为不同的字读音可能相同，但是文字却不同。
另外，还有变音字（当子音碰上母音）或省略音（如上面提 的h），下回再谈了。

自由

你口中所追求的自由
到底建立在什么之上？