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German physicist Heinrich Hertz first demonstrated the existence of radio waves in 1887 using what we now know as a dipole antenna (with capacitative end-loading). On the other hand, Guglielmo Marconi empirically found that he could just ground the transmitter (or one side of a transmission line, if used) dispensing with one half of the antenna, thus realizing the vertical or monopole antenna.
G5RV Antenna without balun. The G5RV antenna is a dipole with a symmetric resonant [ 1 ] feeder line , which serves as impedance matcher for a 50 Ω coax cable to the transceiver . [ 2 ] [ 3 ]
A balun / ˈ b æ l ʌ n / (from "balanced to unbalanced", originally, but now derived from "balancing unit") [1] is an electrical device that allows balanced and unbalanced lines to be interfaced without disturbing the impedance arrangement of either line. [2] A balun can take many forms and may include devices that also transform impedances ...
A halo antenna, or halo, is a center-fed 1 / 2 wavelength dipole antenna, which has been bent into a circle, with a break directly opposite the feed point. The dipole's ends are close, but do not touch, and the ends on either side of the gap may be flared out to form a larger air gap capacitor , whose spacing is used to fine-adjust the ...
A Closed Game (or Double Queen's Pawn Opening) is a chess opening that begins with the moves: . 1. d4 d5. The move 1.d4 offers the same benefits to development and center control as does 1.e4, but unlike with the king's pawn openings where the e4-pawn is undefended after the first move, the d4-pawn is protected by White's queen.
Two element dipole array in front of a one wavelength square reflector used as gain standard. The gain of practical array antennas is limited to about 25–30 dB. Two half wave elements spaced a half wave apart and a quarter wave from a reflecting screen have been used as a standard gain antenna with about 9.8 dBi at its design frequency. [4]
Staunton style chess pieces. Left to right: king, rook, queen, pawn, knight, bishop. The rules of chess (also known as the laws of chess) govern the play of the game of chess. Chess is a two-player abstract strategy board game. Each player controls sixteen pieces of six types on a chessboard. Each type of piece moves in a distinct way.
In a game of chess, the pawn structure (sometimes known as the pawn skeleton) is the configuration of pawns on the chessboard.Because pawns are the least mobile of the chess pieces, the pawn structure is relatively static and thus plays a large role in determining the strategic character of the position.