carr, j j (2001) antenna toolkit (2nd ed )

... used to represent antennas, voltage standing wave ratio (VSWR), impedance, and various methods suitable for con- structing wire antennas in the high-frequency (HF) and very high-frequency (VHF) ... polarized waves are not often used for surface wave commu- nications because the Earth tends to short circuit the electrical (E) field 6 ANTENNA TOOLKIT component. On vertically polarized waves,...

Ngày tải lên: 18/04/2014, 12:28

... of work or energy is the joule (J) where one joule is one newton metre. The joule is defined as the work done or energy transferred when a force of one newton is exerted through a distance of ... mass of 500 kg is raised to a height of 6 m in 30 s. Find (a) the work done and (b) the power developed. [(a) 29.43 kNm (b) 981 W] 9 What quantity of electricity is carried by 6.24 ð 10 21 electrons?...

Ngày tải lên: 18/04/2014, 12:27

... called: (a) a fiber optic (b) a flashlight (c) an optic fiber (d) a xenon bulb 2 A simple fiber optic system would consist of: (a) a light source, an optic fiber and a photo-electric cell (b) a ... approximately: (a) 186 000 ms –1 (b) 3 ϫ 10 9 ms –1 (c) 300 ms –1 (d) 0.3 meters per nanosecond 4 The window with the longest wavelength operates at a wavelength of approximately: (a) 850 nm (b) 15...

Ngày tải lên: 18/04/2014, 12:28

... is, H 0 ϭH(t 0 ). For galaxies which are not too near nor too far, the velocity ␷ is related to the distance d by Hubble’s constant: ␷ ϭH 0 d. (1. 4) (Compare (1. 2), (1. 3) and (1. 4). ) The present ... the curve R(t) meets the t-axis at T at an angle ␣ , then tan ␣ ϭPN/NT ϭR(t 0 ), (1. 5) 1 2 1 2 1 2 8 Some basic concepts TLFeBOOK so that NTϭPN/R(t 0 ) R(t 0 )/...

Ngày tải lên: 17/03/2014, 13:33

... Leptons up (u) electron (e − ) down (d) electron-neutrino (ν e ) strange (s) muon (µ − ) charm (c) muon-neutrino (ν µ ) bottom (b) tau (τ − ) top (t) tau-neutrino (ν τ ) the electron, the electron-neutrino, ... abbreviations for the names of the quarks). 1st generation 2nd generation 3rd generation +2/3 up (u) charm (c) top (t) −1/3 down (d) strange (s) bottom (b) This...

Ngày tải lên: 17/03/2014, 14:38

... main(void) { int i; i=1; printf(“\ti\ti\ti\n ); printf(“\t\t Squared Cubed\n\n ); while(i<1 1) { printf(“\t%d\t%d\t%d\n”, i, i*i, i*i*i); i=i+1; } return 0; } This example was designed ... can be stored in a specified location. For example, in the while expression while((c=getchar ()) != EOF) the inner expression c=getchar () causes the function getchar ()...

Ngày tải lên: 18/04/2014, 12:27

... people the terms antenna and aerial are synonymous. The English plural is normally used for antenna. 14 Antenna, isotropic A hypothetical, idealised, antenna which radiates (or receives) equally in ... wave antenna length for a number of frequencies Frequency (MHz) Length – one quarter wavelength (m/cm) 0.1 750 m 175m 10 7.5 m 100 0.75 m (75 cm) 1 000 0.075 m (7.5 cm) 10 000 0.0075 m...

Ngày tải lên: 18/04/2014, 12:27

... loss () () () =- () ◊ =- ()( ) = () 12 5 0 25 1 75 16 An Introduction to the Linear Regulator + V in R - V z 10 uF + - V out V in(min) > V out + 2.5V R ª V in(min) h FE(min) 1.2 I out(max) V z ... the overcurrent TPRRRT j D JC CS S A WCW CW CW C C max . . () =++ () + = () ∞+∞+∞ () +∞ =∞ qqqA 1 75 5 65 14 50 84 4 TPR T j D JA A max WCW = 16...

Ngày tải lên: 18/04/2014, 12:28

... fundamental) Other terms are as previously defined The amplitude coefficients (a n and b n ) are expressed by: a n = 2 T ͵ T 0 f(t) cos(n␻t) dt (2. 3) and, b n = 2 T ͵ T 0 f(t) sin(n␻t) dt (2. 4) Because ... sawtooth waveform in Fig. 2.6C demonstrates. Figure 2.4 Square wave. 0,0 –F(t) +F(t) –T + T f(–t) f(+t) A 0,0 –F(t) +F(t) –T + T f(–t) f(+t) B Signals and noise 13 An exception...

Ngày tải lên: 18/04/2014, 12:28