Antennas The Last Frontier

Transcription

1 Antennas The Last Frontier 1 F R A N K J. B E A F O R E W S 8 B Hamvention 2010 (r)

2 Space: The final frontier 2 *These are the voyages of the Starship, Enterprise. *Its 5 year mission To explore strange new worlds. *To seek out new life and new civilizations. *To boldly go where no man has gone before. Hamvention (r)

3 Introduction 3 Rules for the Forum Antenna Safety Dipole Fooling Mother Nature Build your own Hamvention (r)

4 Frank J. Beafore WS8B Technical Specialist ARRL, Ohio Section

5 Comments on Antenna Installation Safety 2002 WS8B

6 Antenna Safety Near-by Objects Lightning & EMP Protection Physical Installation Radiation Hazards Grounding Height Safety Belts Lock-Out, Tag-Out 2002 WS8B

7 Antenna Definition The antenna launches energy from a transmitter into space or pulls it in from a passing wave for a receiver. Without a suitable, properly installed antenna, the best transmitter and receiver are useless. Quote: Dr, John Kraus-W8JK, Professor Emeritus, The Ohio State University (Beat Michigan) Columbus, Ohio 2002 WS8B

8 Wave formation Waves are the result of energizing a balanced dipole system. This can be demonstrated by waving a rope, plucking a banjo string or striking a piano key WS8B

9 Radio Waves Radio waves are formed by energizing a dipole (di meaning to cut or dissect and pole is a pole is a pole). The dipole or antenna is a specific length relating to the energizing frequency WS8B

10 Transmission and Reception Radio waves are emitted by an oscillating dipole and escape into electromagnetic space much like music from guitar string, that moves the air near it. The radio receiver detects the radio wave in a manner similar to the human ear detecting a note from a guitar WS8B

11 Transmission / Reception

12 The Dipole The dipole is the fundamental antenna. It is found freely in nature. Consisting of 2 equal length poles, the energy oscillates it oscillates (moves back and fourth) in two directions. Isotropic Dipole Dipole in Space Dipole Near The Earth Horizontal Vertical 2002 WS8B

13 Simple Antenna Dipole

14 Inverted Vee

15 Sloper

16 Double Extended Zepp

17 Double Extended Zepp Emission Pattern 2002 WS8B

18 Antenna Polarization Horizontal Vertical Circular 2002 WS8B

19 Elements of a Radio Wave

20 The Antenna System Transceiver connections Accessories connections Feed line Balun connections Antenna connections Matching system The antenna Ground 2002 WS8B

21 A Typical Antenna System

22 Various Types of Connectors

23 RF Connectors

24 Twin Line

25 Termination of Twin Line

26 Proper Splicing of Rotor Line

27 Construction of a Dipole Radiating Elements End Insulators Center Insulator Feed line Coupling 2002 WS8B

28 Construction Methods for Homemade dipoles 2002 WS8B

29 Examples of Commercial Insulators? What makes an insulator insulate??? 2002 WS8B

30 Examples of Homemade Insulators

31 Various Examples of Homemade Center Insulators

32 Separating Coax Shield

33 Proper Soldering of a Wire Antenna 2002 WS8B

34 Coax Examples

35 Coax Connector Construction

36 Assembling RG-8 or other larger diameter coax.

37 Grounding True Ground Artificial Ground Ground Loops 2002 WS8B

38 Hamvention (r) 38 Lets do some Physics!!!!

39 Radio Wave Speed Same as the speed of light!!! Lets prove this - Hamvention (r) 39

40 Radio Wave Speed: (Gauss's Law for electrostatics) (Ampère-Maxwell Law) Hamvention (r) 40

41 Radio Wave Speed: YEAh!!! Too Cool.. Hamvention (r) 41

42 WaveLength 42 Speed of Light/Frequency Hamvention (r)

43 The Secret Numbers (20 meters) ,794,458 14,250, Hamvention (r)

44 The Secret Numbers ,794,458 Speed of Light 14,250,000 Frequency in HZ Feet / Meter Full Wave in Feet ¼ Wave in Feet Hamvention (r)

45 Most Important Formula Relationship between Frequency and Length Length of a half wave dipole = 486 / Frequency in Megahertz L=468/f (easy to remember with a safety factor) 2002 WS8B

46 468/F(Mhz) 468/ = Let s do one for 2 meters Feet Divide above by 2 = 1.59 feet 46 Multiply by 12 inches in a foot = inches (19.5 to be safe) Hamvention (r)

47 Relationship of Frequency and Wavelength Band Freq (Mhz) 1/2 Wave 1/4 Wave (Meters) (Mhz) (Feet) (Feet) 80m m m m m m WS8B

48 Important Factors Length Width Height above average terrain Surrounding Objects Grounding 2002 WS8B

49 Effects of The Local Environment Type of Support Structure Other Antennas Height above Ground Ground Conductivity Nearby Objects Transmission Line Terrain 2002 WS8B

50 Radiated Signal Factors Directivity Pattern Gain Bandwidth Launch Angle 2002 WS8B

51 ***Choosing an Antenna***

52 Practical Antennas The Half Wave Dipole Most Important Formula Tuning The Antenna Multiband Dipole Operation The Quarter Wave Vertical The Ground Plane Antenna Full Wave Loops 2002 WS8B

53 Practical Antennas (Cont.) Trapped Verticals Hand Held Antennas Verticals for 146,222 and 440 A simple 10 and 15 Meter Vertical 2002 WS8B

54 Construction of a Dual Band Antenna 2002 WS8B

55 Commercial Multiband Vertical Antenna

56 Short Antennas for HT s

57 Home-Brew Ground Plane

58 Homemade Ground Plane

59 Homemade Ground Plane Dimensions

60 Homemade Ground Plane

61 Homemade Vertical

62 Homemade Wire Ground Plane

63 Homemade Roof-Mounted Vertical 2002 WS8B

64 Yagi Beams

65 The Parasitic Antennas The name is derived from: Parasite This means to live off another 2002 WS8B

66 Types of Parasitic Antennas The Yagi (Uda) Log Periodic Cubical Quad Delta Loop 2002 WS8B

67 Elements of a Beam Antenna Driven Element (Dipole) Reflector(s) Director(s) Mast 2002 WS8B

68 Elements of a Beam

69 3 Element Beam Construction

70 Beam Radiation Pattern

71 Variations of Beam Construction

72 Quagie Configuration

73 The Cubical Quad Antenna

74 Delta Loop Beam

75 Fooling Mother Nature Inductors Capacitors L/C circuits Ground systems Hamvention (r) 75

76 Impedance Matching Devices Transformers Balun s Transmatches Tuners 2002 WS8B

77 Coupling Direct Capacitance Delta Match Gamma Match 2002 WS8B

78 Tuning a Wire Antenna

79 Details of a Transmatch

80 Using a Transmatch

81 Using the Transmatch

82 Transmatch Configuration

83 Components of a Transmatch

84 VSWR Voltage Standing Wave Ratio VSWR = V(max) / V(min) Or the ratio of what goes out v. what is reflected back down the coax. High is Bad +3:1 Low is Good- 3:1 I.5:1 is VG Hamvention (r) 84

85 Concept of SWR

86 Reading SWR

87 SWR Curve

88 Installation Photos Hamvention (r) 88

89 Launching a Dipole

90 Fishing Reel Launcher

91 Central Insulator - Choke

92 RF Choke

93 Central Connections

94 Feed Thru

95 Mobile Antenna System

96 Fixed Station Grounding

97 Test Equipment Antennas Multimeter SWR Meter Antenna Analyzer Noise Bridge Field Strength Meter Dummy Load Frequency Counter 2002 WS8B

98 VHF SWR Meter

99 HF SWR Meter

100 Antenna Bridge

101 Frequency Counter

102 Grid-Dip Meter

103

104 Automatic Height Adjustment

105 Adjustments

106 Antenna Experimentation The Last Frontier 2002 WS8B

107 Summary Di-Pole (468/F(Mhz) You can fool Mother Nature Have lot s of fun building your own antenna. 107 Hamvention (r)

108 Conclusion Antennas have always been the radio frontier. From Marconi to the present, Antenna technology remains an opportunity for innovation. Please enjoy your newfound knowledge WS8B