Direction And Position Finding By Wireless
Publisher: Wireless Press
Published: 1920
Place of publication: London; New York
Language: eng
Table of contents: title: CONTENTS; title: INTRODUCTION 1; title: CHAPTER I; title: Directional Transmission for Economic Reasons. — Directive Transmission and Reception for Direction and Position Finding. — Comparison of Visual and Wireless Methods of Direction and Position Finding. — Limitations of Visual Method. — Propagation of Light and Wireless Waves. — Directive Wireless Reception. — Position Finding by Directive Reception. — Historical Notes on Directive and Directional Transmission and Reception. — Mirror Reflectors of Hertz and Marconi. — Screening Methods of Zenneck. — Screen Reflectors of S. G. Brown, Lee de Forest and others. — Horizontal, Inclined and Bent Aerials of Galliot, Kiebitz, Marconi, Braun, Zehnder and others. — Marconi Bent Aerial. — Spaced Aerials of S. G. Brown, Garcia, Lee de Forest, Blondel and J. Stone Stone. — Braun's Heart-shaped Polar Diagram of Reception by Three Spaced Aerials. — H. J. Round's Experiments on Heart-shaped Diagram of Reception using Combined Loop and Open aerials. — Later Progress. Systems of D.F. used during European War. — The Radiophare. — Bellini-Tosi Radiophare. — Telefunken Compass. — Beam Radiophare. — Robinson Directive Transmitter.; title: CHAPTER II; title: THE THEORY OF THE WIRELESS DIRECTION FINDER 12; title: Mental Picture of Wave Propagation. — Wavelength. — Frequency. — Continuous, Interrupted Continuous and Damped Waves. — How a Simple Vertical Aerial Receives. — Aerial Tuning. — Polar Co-Ordinates. — Polar Diagram of a Vertical Aerial. — Equation of Circle Diagram. — How a Frame Aerial Receives. — Polar Diagram of Frame Aerial or Figure Eight Diagram. — Equation of Figure Eight Diagram. — Maximum versus Minimum Signal Strength for D.F. — Systems of Direction Finding. — The Simple Rotating Frame D.F. and Inherent Defects of Frame Aerials for Directive Reception. — Vertical Component and Direct Reception. — Polar Diagram of Figure Eight Distorted by Vertical and Direct. — Reduction and Elimination of Vertical. — Grid Condenser or Compensator Method. — Earthed Mid Point of Coupling Coils. — The Shielded Transformer. — Elimination of Direct. — Displacement Current Effects. — Determination of Sense or Absolute Direction. — Cardiod, Heart-shaped or Apple Diagram of Reception. — Equation of Heart-shaped Polar Diagrams — The Heart-shape Circuit. — Phase Adjustment of Heart-shape with Tuned Aerials. — Reversal of Sense by Reversal of Coupling or Incorrect Phasing. — Robinson System. — Errors. — Direction Finding with the Robinson System. — Avoidance of 90° Ambiguity. — Marconi-Bellini-Tosi System. — Theory of Radiogoniometer. — Conditions for Accurate Working of M.-B.-T. System. — Phase Relation of Aerial Currents, Balancing, etc. — Symmetry of Aerials. — Symmetry of Radiogoniometer. — Mutual Inductance between Aerial Circuits. — Timed Aerial M.-B.-T. Circuit. — Aperiodic Aerial System. — Coupling Error of Tight Coupled Radiogoniometer. — Correction of Coupling Error. — Receiving Qualities of Aperiodic Aerials. — The Simple Aperiodic Aerial Circuit. — Aperiodic Aerial with Loose Coupled Intermediate Circuit. — Heart-shape Circuit with Resistance Phasing of the Open Aerial. — Complete Aperiodic Heart-shape Circuit. Aerial Current Phase Relations in Loose Coupled Aperiodic Aerial Heart-shape Circuit. — Radiogoniometer for Sense Determination.; title: CHAPTER III; title: VALVE AMPLIFIERS AND DETECTORS 68; title: The Crystal as a Rectifier. — Theory of Rectification. — The Thermionic Valve. — Valve as a Rectifier. — Three Electrode Valve. — Saturation. — Three Electrode Valve as a Rectifier. — Elimination of Interference by Saturation of Rectifier. — Valve as a Magnifier. — Reaction. — Heterodyne or Beat Reception of Continuous Waves. — The Heterodyne or Independent Local Oscillator. — Sensitiveness of Heterodyne Reception. — Necessity for Rectification before Note Magnification or Telephone Reception. — Valve as a Note Magnifier. — High Frequency Cascade Amplifiers. — Pure Resistance Amplifier. — Voltage Magnification of a Valve Circuit. — Magnification Constant. — Transformer Amplifiers. — Characteristics of Cascade Amplifiers. — Aperiodic Transformer Amplifier.; title: CHAPTER IV; title: MAPS 97; title: Earth. — Angular Latitude and Longitude. — Linear Latitude and the Nautical Mile. — Linear Longitude and the Geographical Mile. — Positions on Earth's Surface. — Great Circles. — Convergency. — Types of Maps. — Gnomonic Chart. — Gnomonic Graticule. — Retro-Azimuthal Chart. — Orthomorphic Cylindrical Projection or Mercator's Projection. — Distances on Mercator's Chart. — Comparison of Properties of Gnomonic and Mercator's Charts. — Rhumb Line. — Limitations of Mercator's Chart for D.F. — Correction of Azimuthal Errors in Mercator's Chart. — Half-Convergency. — Sign of Half-Convergency. — Line of Bearing. — British Ordnance Survey Maps.; title: CHAPTER V; title: POSITION FINDING 121; title: Methods of Position Finding by Directive Reception. — The Shore D.F. Station. — Position Line by Means of One Shore D.F. Station. — Cross Bearings by Means of Two Shore D.F. Stations. — Fix by Means of Two Associated Shore D.F. Stations. — General Procedure. — Extract from Admiralty "List of Lights W/T. D.F. Stations, etc." — Laying off Position Lines. — The "Cocked Hat." — Practical Examples of the Use of Gnomonic and Mercator's Charts on the Calibration of a D.F. Station. — Choice of Gnomonic Graticule. — Locating the D.F. and Transmitting Stations on the Graticule. — Use of Mercator's Chart. — Correction for Half -Con vergency. — Discrepancies in Calculated and Measured Bearings. — The Ship Direction Finding Station. — Relative and True Bearings. — Position Line from Bearing of One Station. — Position Line from Bearings of Stations "In Transit." — Fix by Cross Bearings on Two Stations. — Cross Bearings on Mercator's Chart. — The Station Pointer. — Cross Bearings on Gnomonic Chart. — Fix by Cross Bearings of Three Stations. — Allowance for Distance Moved by Ship Whilst Taking Cross Bearings. — Position Circle. — Angle Subtended at Ship by Two Shore Stations. — Intersecting Position Circles. — Angles Subtended at Ship by Three Shore Stations. — Special Case when Position Circles Coincide. — Running Fix by Bearings on Single Station. — Prevention of Collision. — Vessels in Distress. — Examples of Wireless Position F hiding -. — Example of a Fix by Cross Bearings on Long Distance Stations using a Nautical Chart. — Above Example using a Gnomonic Graticule. — Example of a Fix by Cross Bearings on Short Range Stations.; title: CHAPTER VI; title: NIGHT EFFECT AND OTHER FREAK PHENOMENA 161; title: Coast Refraction. — Symptoms of Night Effect. — Modern Theory of Night Effect. — Polarisation of Electro-magnetic Waves. — Wave having Vertical Angle of Incidence and its Effect upon Polar Diagram of Reception of Simple Frame Aerial. — Relation Between Direction of Rotation of Plane of Polarisation and Direction of Rotation of Apparent Bearing. — Ionisation of Air and the Heaviside Layer. — Direct Path and Reflected Path of Waves from Transmitter to Receiver. — Causes of Vertical Polarisation of Magnetic Field in Reflected Wave. — Form of Transmitting Aerial. — Effect of Earth's Magnetic Field. — Relative Phases of E.M.F.'s induced in a Receiving Frame by the Direct and Reflected Waves. — Phase Relations between Components of Reflected Wave. — Interference effect. — Summary of Night Effect Conditions. — Sunset Variations of Signal Strength and Bearing. — Experimental Confirmation of Theory of Night Effect. — Observations of 90° Error. — Frequency and Violence of Night Effects. — Mechanism of the 90° Error Phenomenon. — Graphical Representation of a Type of Night Effect. — Comparison of Theoretical and Experimental Graphs. — Direction Finding in Three Dimensions. — Common Types of Night Effect. — Land and Sea. — Marking and Spacing Wave Discrepancies. — Minimum Distance Between Transmitter and Receiver for Night Effect. — Spark and Continuous Waves Change of Note of a Spark Signal. — Elimination of Night Effect Errors in Bearings. — Horizontal Frame. — Spaced Vertical Aerials or "Open Frame." — Spaced and Opposed Frames of Franklin and Weagant. — Heart-shaped Diagram. — Graphical Representation of Heart-shaped Polar Diagram under Influence of Night Effect. — Comparison of Simple Frame and Heart-shape Circuit in Practice. — Value of Heart-shape Circuit in Detecting Presence of Night Effect.; title: CHAPTER VII; title: THE SHORE D.F. STATION 202; title: Choice of Site. — Fixing Geographical Position of Site. — Correct Orientation of Station or Aerial Systems. — Methods of Finding the Direction of True North. — Geographical Method using Theodolite and Map of District. — Prismatic Compass. — The Marconi-Bellini-Tosi Shore Installation. — Laying-out Site of M.-B.-T Station.-^ Aerial Systems, their Construction, Insulation and Method of Support. — Triangular Frames. — Construction of Aerial. — Leading-in of Aerials. — Transposition of Lead-In. — Position of Receiving Building. — Earth System. — Receiving Apparatus. — Radiogoniometers for Tuned and Aperiodic Aerials. — Points in Design of Radiogoniometer. — D.F. Wave-Meter and Timing Buzzer. — The Shielded Transformer. — Points in the Design of the Shielded Transformer. - Layout and Adjustment of Receiving Apparatus. — Tuned Aerial Circuit. — Lightning Arrester and Earthing Switch. — Wavemeter and Tuning Buzzer. — Aerial Disconnecting Switches. Wiring of Circuit. — Installation of Radiogoniometer. — Aerial Tuning Condensers. — Reception of Continuous Waves by Means of Separate Local Oscillator. — Tuning and Balancing. — To Check the Circuit for "Vertical;" "Direct" and "Mutual." - Direction Finding. — Swing Readings. — Aperiodic Aerial Circuit. — Differences in Installation of Aperiodic and Tuned Aerial Circuit. — Earthing of Receiving Apparatus. — Tuning. — Checking for Vertical, Direct and Mutual. — Direction Finding. — Sharpness of Minima and Aperiodic Aerial Circuit. — Aperiodic Aerial Loose-Coupled Intermediate Circuit Heart-shape Receiver. — Uses of Above Circuit. — Arrangement of Circuit. — Intermediate Circuit. — Open Aerial Circuit. — Adjustment. — Factors Producing Indefinite Minimum with Heart-shape Reception. — Switching for D.F., Sense and Stand-By. — A Shore Service Direction Finding Installation (Marconi). — Diagram of Connections. — Description of Component Units. — Calibration. — Plotting Error Curve. — Quadrantal Error. — Elimination of Quadrantal Error in M.-B.-T. System. — Precautions in Making Aerial Adjustments for Calibration. — Choke Method of Calibration. — Calibration by Reducing Area of One Frame. — Comparison of Wireless and Magnetic Compass Correction. — Multiplex Shore D.F. Station.; title: CHAPTER VIII; title: THE SHIP D.F. STATION 264; title: Choice of Site for Aerials. — Chart Room or Wireless Office for D.F. Receiver. — Aerial Systems and Methods of Support. — Centre Support for Temporary Aerials. — Construction and Insulation of Aerials. — Aerials of R.M.S.P. "Andes" and S.S. "Ballygally Head." — Leading-In of Aerials. — Transposed Lead-In. — Shielding. — Bulkheads. — Lead Covered Paper Cables. — Circuit Alterations Necessitated by Long Cables. — Aerial Transformers. — Mid-Point Connection. — Static Leak. — Parallel Connection of Calibrating Choke. — A Marine Direction Finding Installation (Marconi). — Diagram of Connections. — Description of Component Units. — Layout of Apparatus. — Adjustment of Apparatus and Calibration. — To Find Direction of Ship's. Head and Hence the True Bearing of a Transmitting Station from the D.F. Bearing. — Case I, when Ship is alongside a Quay. — Case II, when Ship is not alongside a Quay. — The Magnetic Compass. — Magnetic Variation and Deviation. — Total Compass Error. — Case III, when Ship is not alongside a Quay and Compass Error is Unknown. — Case IV, when Ship is at Anchor or Moored. — Calibration. — Calibrating on Signals from Known Transmitting Stations. — Calibration when Ship is at Anchor or Moored. — Calibration when Ship is Under Way. — Special Transmitters for Calibration. — Taking Bearings. — Gong Signalling from W/T Office to Bridge. — The D.F. and the Gyro Compass.; title: CHAPTER IX.; title: THE AIRCRAFT D.F. INSTALLATION 298; title: The Problem of Aircraft Navigation. — Errors in Bearings. — Magneto Noise. — Engine Noise. — Systems of Aircraft D.F. — Wing Coil System. — Drift. — Magnetic Compass. — Position Finding by Wing Coil System. — Robinson D.F. — Relative Sizes of Main and Auxiliary Coils. — Robinson D.F. Adapted to the Wing Coil System. — Marconi -Bellini -Tosi System. — An Aircraft D.F. Installation (Marconi). — Diagram of Connections. — Description of Component Units. — Testing and Calibration of the Aircraft D.F. — Method of Rigging Wing Coils and M.-B.-T. Aerials bn Aircraft. — M.-B.-T. Fore and Aft Aerial. — Double Turn Fore and Aft Aerial. — Precautions against Magneto Interference. — Screened Ignition. — Screened Sparking Plug. — Temporary or Additional Screening Measures. — Effects of Vibration.; title: CHAPTER X; title: FAULT CLEARING AND MAINTENANCE 316; title: Common Symptoms of Failure. — No Signals. — Test of Insulation of H.F. Cascade Amplifier. — Test for Continuity of H.F. Cascade Amplifier. — Signals Fall off Gradually in Strength. — Noises in Telephones. — Bearings of All Stations in Same Direction. — Figure Eight Minima not Opposite on Scale. No Directional Reception. — Bearings all Too High or Too Low. — Bearings Incorrect in Certain Directions Only. — More than Two Minima with Figure Eight Circuit. — Indefinite Minima with Figure Eight Reception. — Bearings Incorrect on Certain Wavelengths only. — Heart-shape Balance un stable. — Faults Due to Wrong Connections of M.-B.-T. Aerials to Radiogoniometer. — Practical Example of Wrong Connection of M.-B.-T. Aerials.; title: CHAPTER XI; title: NOTES ON FIELD AND NAUTICAL ASTRONOMY 323; title: Solar Observations. — Positions of Heavenly Bodies. — Declination. — Polar Distance. — Right Ascension. — Sidereal Time. — Apparent Time. — Mean Time. — Greenwich Mean Time. — Equation of Time. — Zenith Distance. — Azimuth. — Hour Angle. — Hour Angle and Difference of Longitude. — Timing of Observations. — Series of Problems with Examples Worked. Out; — To Calculate the Time of Apparent Noon at Place in Terms of G.M.T. or Local Standard Time. — To find Time of Apparent Noon at Place and Hence the Longitude by Observations of Equal Altitudes of the Sun. — To Find the Meridian Altitude of the Sim by Observation and Hence the Latitude. — To Find Approximate True North by Observation of the Sun's Meridian Passage. — To Find True North from the Sim's Azimuth. — To Find Compass Error from the Sun's Azimuth. — To Find the Azimuth and Zenith Distance (Calculation of Great Circle Angle and Distance). — To Find the Great Circle Angle (Alternative Method). — To Plot a Great Circle on a Mercator's Chart. — To Draw a Gnomonic Chart (Graticule).; title: BIBLIOGRAPHY 350; title: INDEX 305; title: LIST OF ILLUSTRATIONS.; title: Frontispiece. Half-Convergency Diagram.; title: Fig.; title: 1 Position Finding by Directive Reception at two Stations A and B.; title: 2 The Marconi "Inverted L" Aerial.; title: 3 The Telefunken Compass.; title: 4 Measurement of Wavelength.; title: 5 Types of Wave Trains.; title: 6 Induction of Alternating E.M.F. in an Open Aerial by an Electro-magnetic Wave.; title: 7 Diagram to Illustrate the Use of Polar Co-ordinates.; title: 8 Polar Diagram of Open Aerial.; title: 9 Frame Aerial in Position of Maximum Linkage with Magnetic Flux in a Wave.; title: 10 Phase of Induced E.M.F. in Frame Aerial.; title: 11 Variation of Linkage with Rotation of Frame.; title: 12 Polar Curve of Simple Frame as found from Diagram of Fig. 11.; title: 13 Theory of Cosine Diagram.; title: 14 Theoretical Cosine or Figure Eight Diagram of Simple Frame.; title: 15 Box Form Frame Aerial.; title: 16 Pancake Form Frame Aerial.; title: 17 Circuit of Simple Frame D.F.; title: 18 Figure Eight Diagram Distorted by Vertical.; title: 19 Cause of Vertical.; title: 20 Figure Eight Diagram of Frame with Circle Diagram of Vertical.; title: 21 Figure Eight Diagram distorted by "Out of Phase Vertical."; title: 22 Earthed Midpoint of Aerial Coupling Coils.; title: 23 The Shielded Transformer.; title: 24 The Heart-shaped Diagram.; title: 25 Addition of E.M.F.s by Couplings.; title: 26 Heart-shaped Diagram by Tuned Open and Frame Aerials with Tuned Intermediate Circuit.; title: 27 Method of Avoiding Separate Open Aerial.; title: 28 Theory of Circuit for Tuned Heart-shaped Diagram.; title: 29 The Robinson D.F. Circuit.; title: 30 Theory of Robinson D.F.; title: 31 Ambiguity of Robinson D.F.; title: 32 The Marconi-Bellini-Tosi D.F.; title: 33 Action of Radiogoniometer.; title: 34 Theory of Radiogoniometer.; title: 35 Circuit of Tuned M.-B.-T. D.F.; title: 36 Circuit of "Aperiodic" M.-B.-T. D.F.; title: 37 Transformer Action in Aperiodic M.-B.-T. D.F.; title: 38 Theory of Coupling Error of Radiogoniometer.; title: 39 Graph of Coupling Error of Radiogoniometer.; title: 40 Compound Search Coil.; title: 41 Aperiodic M.-B.-T. D.F. with Shielded Transformer.; title: 42 Aperiodic M.-B.-T. D.F. with Loose Coupled Jigger.; title: 43 Aperiodic Circuit for Heart-shaped Diagram.; title: 44 Theory of Aperiodic Circuit for Heart-shaped Diagram.; title: 45 Simplified Circuit for Heart-shaped Diagram as "Sense" Indicator.; title: 46 Extended Theory of Aperiodic Circuit for Heart-shaped Diagram.; title: 47 Oscillatory Circuit.; title: 48 Oscillatory Circuit with Rectifier.; title: 49 Characteristic Curve of Carborundum Crystal.; title: 50 Circuit of Fig. 48 with addition of Potentiometer.; title: 51 Theory of Rectification by Curvature of Characteristic.; title: 52 Characteristic Curve of Fleming Valve.; title: 53 Circuit of Fleming Valve Rectifier.; title: 54 Use of Common Battery for Heating Filaments and Operating Potentiometer.; title: 55 Circuit for obtaining Characteristic Curves of 3-Electrode Valves.; title: 56 Characteristic Curve of 3-Electrode Valve.; title: 57 Grid Volt-Plate Current Curves of Marconi V-24 Valve.; title: 58 Section of 3-Electrode Valve.; title: 59 Marconi V-24 Valve.; title: 60 The 3-Electrode Valve as a Rectifier.; title: 61 Saturation Method of Eliminating Interference.; title: 62 Magnification and Rectification by 3- Electrode Valves.; title: 63 Use of Reaction.; title: 64 Beat Reception.; title: 65 Circuit of Local Oscillator.; title: 66 Increased Efficiency of Rectification due to Heterodyne Reception.; title: 67 Two-Stage Note Amplifier.; title: 68 Two-Stage Note Amplifier with Common Battery.; title: 69 Tuned Cascade High Frequency Amplifier.; title: 70 Theory of Resistance Amplifier.; title: 71 Theory of Inductance Amplifier.; title: 72 Cascade Amplifier.; title: 73 Cascade Transformer Amplifier with Common Batteries.; title: 74 Voltage Magnification Curves of Different Types of Amplifier.; title: 75 The Hemispheres.; title: 76 Latitude.; title: 77 Longitude.; title: 78 Great Circle, Illustrating Convergency.; title: 79 Great Circle, Illustrating Convergency.; title: 80 True Bearing.; title: 81 Optical Principle of Gnomonic Projection.; title: 82 Optical Principle of Gnomonic Projection.; title: 83 Gnomonic Projection by Optical Means.; title: 84 Zenithal Properties of Gnomonic Projection.; title: 85 Gnomonic Chart with Point of Contact at the Pole.; title: 86 Tangent Planes of a Series of Gnomonic Graticules.; title: 87 Cylindrical Projection by Optical Means.; title: 88 Development of Cylindrical Projection of Fig. 87.; title: 89 Great Circle on Globe.; title: 90 Great Circle oh Gnomonic Chart.; title: 91 Discrepancy between Great Circle Bearing and Mercatorial (or Rhumb Line) Bearing.; title: 92 Sign of Half-Convergency.; title: 93 Change in True Bearing as A approaches B along Great Circle.; title: 94 Change in True Bearing as A approaches B along Rhumb Line.; title: 95 Line of Constant Bearing.; title: 96 43° line of Bearing with respect to B.; title: 97 Position Line from Single Shore D.F.; title: 98 Fix from Two Shore D.F. Stations.; title: 99 Degree of Accuracy of Wireless Fix.; title: 100 Variation in Accuracy of Wireless Fix with Relative Position of Ship and D.F. stations.; title: 101 increase in Accuracy of Wireless Fix due to third D.F.; title: 102 A Method of Plotting, at the Control Station, a Wireless Fix from three D.F. stations.; title: 103 Use of the Gnomonic Graticule in obtaining True Bearings of Transmitting Stations from a D.F.; title: 104 Use of Mercator's Chart in obtaining True Bearing of a Transmitting Station from a D.F.; title: 105 True Bearing of Transmitting Station P from Ship 0 is the Sum of the Bearing of the Ship's Course and the Wireless Bearing of P relative to the Ship's Course.; title: 106 Position Line on Mercator's Chart from True Bearing of one Transmitting Station.; title: 107 Position Line on Gnomonic Chart from True Bearing of one Transmitting Station.; title: 108 Position Line from Transmitting Stations "In Transit."; title: 109 Alternative case of Position Line from Transmitting Stations "in transit."; title: 110 Suggested Method of Navigating Atlantic Flight by Transit Bearings on Terminal Transmitting Stations.; title: 111 Fix by Cross Bearings, from Ship D.F., on two Transmitting Stations.; title: 112 Plotting Fix by Cross Bearings on Mercator's Chart.; title: 113 Plotting Fix by Cross Bearings on Gnomonic Chart.; title: 114 A Method of Plotting Fix when an Interval of Time elapses tyetween taking Cross Bearings on two Transmitting Stations.; title: 115 A Method of Plotting Fix when Intervals of Time elapse between taking Cross Bearings on three Transmitting Stations.; title: 116 The Position Circle.; title: 117 Geometry of the Position Circle.; title: 118 Construction foir Finding Centre of a Position Circle.; title: 119 Intersecting Position Circles.; title: 120 Coincident Position Circles.; title: 121 The Running Fix.; title: 122 Long Range Wireless Fix using Mercator's Chart.; title: 123 Long Range Wireless Fix using Gnomonic Graticule.; title: 124 Short Range Wireless Fix when Time Elapses between taking Cross Bearings.; title: 125 Wireless Fix by Cross Bearings using Station Pointer.; title: 126 Analogy illustrating Refraction.; title: 127 Effects of Coast Refraction.; title: 128 Frame Aerial in Position of Maximum Magnetic Linkage for Horizontally Incident and Normally Polarised Wave.; title: 129 Frame Aerial and Horizontally Incident, Obliquely Polarised Wave.; title: 130 Obliquely Polarised Wave, resolved into Vertically and Horizontally Polarised Components.; title: 131 Frame Aerial in Position of Maximum Magnetic Linkage for Normally Polarised Wave with a Vertical Angle of Incidence.; title: 132 Frame Aerial in Position of Minimum Magnetic Linkage for Wave having a Vertical Angle of Incidence and Vertically Polarised Magnetic Force.; title: 133 Frame Aerial in position of Maximum Magnetic Linkage for Wave as in Fig. 132.; title: 134 Polar Diagram of Reception of Simple Frame for Wave with Vertically Polarised Magnetic Force.; title: 135 Compare with Fig. 132.; title: 136 Position of Zero Magnetic Linkage for Normally Polarised Wave with a Vertical Angle of Incidence.; title: 137 Position of Zero Magnetic Linkage when Plane of Polarisation of Magnetic Force in Wave is in direction "d."; title: 138 Position of Zero Magnetic Linkage when Plane of Polarisation of Magnetic Force in Wave is in direction "c."; title: 139 Paths of Direct and Reflected Rays from Transmitter to Receiver.; title: 140 Paths of Direct and Refracted Rays from Transmitter to Receiver.; title: 141 Multiple Reflection of Indirect Ray.; title: 142 Method by which Abnormally Polarised Wave H., radiated from Horizontal Portion of an Inverted L Aerial, may reach a D.F. Station by Reflection.; title: 143 Phase Relation, at Transmitting and Receiving Station, as a Function of Distance between Stations and Wavelength.; title: 144 Interference Effect between Direct and Reflected Waves.; title: 145 Example of Extreme Variation in Apparent Bearing.; title: 146 Alternative method of Plotting Graph of Fig. 145.; title: 147 Illustrating the 90° Error Phenomenon as plotted in Figs. 145 and 146.; title: 148 Alternative explanation of 90° Error.; title: 149 Another example of Extreme Sunset Variations in Apparent Bearing.; title: 150 Polar Diagrams of A, B and C Component Waves, using Figure Eight Reception.; title: 151 Vector Diagram for Summation of A, B and C Component Waves.; title: 152 Series of Theoretical Polar Diagrams illustrating the result of Night Effect on Figure Eight Reception.; title: 153 Results of Fig. 152 plotted to show their resemblance to Figs. 145 and 149.; title: 154 Suggested Device for obtaining Azimuth and Zenith Angles of a Source of Electro-magnetic Waves.; title: 155 Adcock's Scheme for Elimination of Night Effect.; title: 156 Franklin and Weagant Spaced and Opposed Frames for Elimination of Night Effect.; title: 157 Polar Diagram of A, B and C Component Waves using Heart- shape Reception and when the Reflected Wave has a Vertical Angle of Incidence.; title: 158 Reduction in Receiving Power of Vertical Aerial when Reflected Wave has a Large Vertical Angle of Incidence.; title: 159 Series of Polar Diagrams as in Fig. 152, but using Heart-shape Reception.; title: 160 Enlarge view of part of Fig. 159 (d).; title: 161 Figure Eight and Heart-shaped Polar Diagrams under influence of Night Effect. Freehand sketches during actual Aural Reception.; title: 162 Further sketches made during Aural Reception illustrating Assymmetry of Heart-shaped Diagram whilst Direction of Zero Reception remains correct.; title: 163 Determination of the Direction of North from Bearings obtained from a Map.; title: 164 Map of District (imaginary) shown in Fig. 163.; title: 165 Triangular Aerials with Single Mast.; title: 166 Triangular Aerials with Central Mast and Four Short Comer Masts.; title: 167 Square Aerials with Four Masts.; title: 168 Plan of M.-B.-T. Triangular Aerial System.; title: 169 Proportions of Triangular Aerial.; title: 170 Simple Method of Measuring off Wire for Triangular Aerials.; title: 171 Masthead Arrangement of Triangular Aerials.; title: 172 Method of Anchoring Triangular Aerial.; title: 173 Short Lead-in for Tuned Aerials.; title: 174 Long Lead-in showing Transposition.; title: 175 Temporary Lead-in for Aperiodic Aerials.; title: 176 Radiogoniometer for use with Tuned Aerials.; title: 176a Field Coil Connections.; title: 177 Radiogoniometer for use with Aperiodic Aerials.; title: 178 D.F. Wavemeter and Tuning Buzzer.; title: 179 Shielded Transformer with Tertiary Winding.; title: 180 Connections of Double Range Shielded Transformer with Reaction Coupling (see Fig. 181).; title: 181 Front view of Shielded Transformer (see Fig. 180).; title: 182 Effect of Capacity of Transformer Windings.; title: 183 Lay-out of Tuned Aerial Circuit.; title: 184 (a) Two Degrees of "Vertical."; title: (b) Twenty Degrees of Rotation.; title: (c) Combination of (a) and (b).; title: 185 Lay-out of Aperiodic Aerial Circuit.; title: 186 Lay-out of Aperiodic Heart-shaped Diagram Circuit.; title: 187 Distortion of Heart-shaped Diagram due to Too Great an E.M.F. induced by Vertical Aerial.; title: 188 Distortion of Heart-shaped Diagram due to Too Great an E.M.F. induced by Loop Aerials.; title: 189 Switching Circuit for (l) "D.F." (2) "Sense" and (3) "Stand By."; title: 190 M.-B.-T. Shore Pattern D.F. Receiver (Marconi).; title: 191 Circuit of D.F. Receiver Shown in Fig. 190.; title: 192 Radiogoniometer. (See Fig. 190).; title: 193 Intermediate Circuit Tuning Condenser. (See Fig. 190).; title: 194 Transformer Panel. (See Fig. 190).; title: 195 Jigger Condenser. (See Fig. 190).; title: 196 Jigger Panel. (See Fig. 190).; title: 197 H.F. Amplifier Control Panel. (See Fig. 190).; title: 198 H.F. Amplifier. (See Fig. 190).; title: 199 Double Note Magnifier. (See Fig. 190).; title: 200 Error Curve of Uncalibrated D.F.; title: 201 Distortion of Bearings of Uncalibrated D.F.; title: 202 Methods of Reducing Temporarily, Area of M.-B.-T. Aerial.; title: 203 Inverted Fore and Aft Loop.; title: 204 Separated Loops.; title: 205 Diamond-shaped Loop to Avoid Unbalance.; title: 206 Fore and Aft Loop Between Funnels.; title: 207 Aerial Lower Centre Support showing Junction Boxes for Leading-in Cables.; title: 208 Temporary Installation; Aerial Lower Centre Support with Rubber Cable Lead-in.; title: 2P9 Aerial Apex Insulator.; title: 210 Corrugated Ebonite Insulator and Spring for Support of Outer Comers of Loops.; title: 211 General View of D.F. Aerials of the R.M.S.P. "Andes."; title: 212 D.F. Aerials of the S.S. "Ballygally Head."; title: 213 Screened Lead-in.; title: 214 Lead-Covered, Paper Insulated Twin Cable for Lead-in.; title: 215 Interior of W/T Office, showing , Internal Junction Boxes.; title: 216 Self-Capacity of Lead-Covered Twin Cable.; title: 217 Arrangement of Ratio Transformers in Aerial and Lead-in*; title: 218 M.-B.-T. Marine Pattern D.F. Receiver (Marconi).; title: 219 Circuit of D.F. shown in Fig. 218.; title: 220 Radiogoniometer. (See Fig. 218).; title: 221 Variable Tuning Condenser. (See Fig. 218).; title: 222 Transformer Panel. (See Fig. 218).; title: 223 Amplifier Panel. (See Fig. 218).; title: 224 Earthing Relay. (See Fig. 218).; title: 225 Calibrating Chokes. (See Fig. 218).; title: 226 Error Curve of Uncalibrated Ship D.F. Installation.; title: 227 The Wing Coil Method ot D.F.; title: 228 Swing Bearing using the Wing Coil.; title: 229 Drift of Aeroplane due to Wind on Beam.; title: 230 Effect of Drift when Flying Head-on to Transmitting Station Objective.; title: 231 Robinson D.F. using Box Type Coils.; title: 232 Robinson D.F. using Pancake Type Coils. Mounted in Fuselage of Handley- Page Aeroplane.; title: 233 Combined Box and Pancake Type Coils used by U.S. Navy.; title: 234 Robinson D.F. adapted to Wing Coil Method of D.F.; title: 235 Circuit of M.-B.-T. Aircraft D.F.; title: 236 M.-B.-T. Aircraft D.F. Installation (Marconi).; title: 236a Key Diagram for Fig. 236.; title: 237 Rigging of M.-B.-T. Fore and Aft Aerial on "Short" Flying Boat.; title: 238 M.-B.-T. Fore and Aft Aerial Supported on Masts. (See Fig. 239).; title: 239 View of Fore Mast used in Special Cases to support M.-B.-T. Fore and Aft Loop.; title: 240 Method of Running Fore and Aft M.-B.-T. Loop to Clear Engine on Single Engine Machine.; title: 241 "Tuned Stopper" Circuit for Elimination of Magneto Interference.; title: 242 Rolls-Royce Engine fitted with Screened Ignition and Screened Sparking Plugs.; title: 243 Screened Sparking Plug.; title: 244 True Position and Geographical Position of Heavenly Bodies.; title: 245 Movement of the Earth Round the Sun.; title: 246 Azimuth, Zenith Distance and Hour Angle.; title: 247 Contacts of Sun's Image with Cross Wire of Theodolite.; title: 248 Latitude as a Function of Sun's Altitude.; title: 249 Latitude as a Function of Sun's Altitude and Declination.; title: 250 To find Direction of True North from the Sun's Meridian Passage.; title: 251 Great Circle Angle and Distance by Calibration.; title: 252 Calculation of Intersections of Great Circle AB with Meridians in order to Plot Great Circle on Mercator's Chart.; title: 253 Construction of a Gnomonic Graticule.; title: 254 Portion of Completed Graticule.