Omnidirectional Slots Antenna

Omnidirectional antenna with high gain, low profile, vertical polarization, even CP polarization is very difficult to design, although it is from the dipole. In this book, a novel idea that the running wave in the coaxial wire is disturbed by the orthogonal slot array on the cylindrical metal shell is introduced, which radiates the CP wave in omni-direction. When feeding on two ends of the coaxial wire respectively, there will appear left hand circularly polarized (LHCP) omnidirectional radiation or right hand circularly polarized (RHCP) omnidirectional radiation. By introducing the T-shaped feed structure, the coaxial wire with slot array can conveniently produce the LHCP and RHCP radiation diversity with one end feeding. In the further, combining with the directional antenna, it will generate the pattern diversity in the half-sphere space. The antenna of the coaxial wire with slot array can further transform into conical CP beam antenna if the coaxial wire becomes into a conical frustum. By introducing the PIN diode into the slot, the antenna of the coaxial wire with slot array can radiate the reconfigurable directional beam by switching the states of the PIN diodes. By introducing a novel switchable microwave circuit, the omnidirectional /directional pattern switchable antenna can be realized easily. This book proposes a continues method to develop the potentialities of the omnidirectional antenna. And the readers can study the method or ideas of the omnidirectional slots antenna, even graft the CP or diversity methods to other antennae. Preface Acknowledgments Contents About the Author Abbreviations List of Figures List of Tables 1 Introduction 1.1 Background and Demand 1.2 Research Development of the Omnidirectional Circularly Polarized Antennas 1.2.1 Omnidirectional Circularly Polarized Antennas 1.2.2 Research on Omnidirectional Circularly Polarized Tapered Beam Antenna 1.2.3 Omnidirectional Polarization Reconfigurable Circularly Polarized Antenna 1.3 Content and Construction of the Book References 2 Basic Theory of Omnidirectional Antenna and Slot Array 2.1 The Basic Theory of the Transmission Line 2.1.1 The Uniform Transmission Line 2.1.2 The State Parameters and Impedance of the TL 2.1.3 The Short State of the Lossless TL 2.2 The Basic Theory of Coaxial Wave-Guide 2.2.1 The Main Mode of Coaxial Transmission Line—TEM 2.2.2 The Parameters of the Main Mode in CTL 2.2.3 High Order Modes in the Coaxial Transmission Line (CTL) 2.3 The Basic Theory to Slot Antenna 2.4 Basic Theory of Array Antenna 2.4.1 Product Theorem of Pattern 2.4.2 Uniform Linear Array 2.4.3 Grating Lobe and the Interval 2.5 Summary References 3 Principles of Omnidirectional CP Slot Array Antenna 3.1 Introduction 3.2 Geometry Structure and Principle 3.2.1 Antenna Structure 3.2.2 Design Principle to Omnidirectional CP Radiation Performance 3.2.3 Impedance Matching and Feed Design 3.3 Antenna Performance Simulation and Verification 3.4 Experiment Results Analysis 3.5 Improved Omnidirectional CP Coaxial Slots Antenna with Compact Size and High Gain 3.5.1 Improved Antenna Geometry Structure 3.5.2 Improved Antenna Design 3.5.3 Antenna Performance Discussion 3.6 Summary References 4 Principles of Omnidirectional Dual-CP Slot Array Antenna 4.1 Introduction 4.2 Geometry Structure, Principle and Antenna Design 4.2.1 Antenna Structure 4.2.2 Dual CP Principle 4.3 Antenna Performance Analysis 4.4 Summary References 5 Dual CP Polarization Diversity and Space Diversity Antennas Enabled by a Compact T-Shaped Feed Structure 5.1 Introduction 5.2 T-Shaped Feed Structure 5.2.1 TFS Geometry Structure 5.2.2 TFS Impedance Transformation 5.2.3 TFS Performance by Simulation 5.3 The Improved Dual CP Omnidirectional Antenna Fed by TFS 5.3.1 The Principle and Structure of the Improved DCPOA 5.3.2 Performance of the Improved DCPOA 5.3.3 DCPOA Parametric Study and Analysis 5.3.4 Experimental Verification and Analysis 5.3.5 Comparison with Other Dual CP Antenna 5.4 TFS-Enabled Space Diversity Antenna 5.4.1 The Principle of the SDA with TFS 5.4.2 SDA Structure and Performance 5.4.3 Experimental Verification and Analysis 5.4.4 Comparison with Other Spatial Diversity Antennas 5.5 Summary References 6 A Circular Truncated Cone Slot Antenna with Circular Polarized Conical Beam 6.1 Introduction 6.2 Antenna Design and Analysis 6.3 Parameter Analysis 6.4 Results and Discussion 6.5 Summary References 7 Half-Space Covered Antenna for Air-Ground Communication 7.1 Introduction 7.1.1 The Principle of the Half Space Covering Antenna 7.1.2 The Key Parameters of the Half Space Covering Antenna 7.2 Performance Analysis 7.3 Summary References 8 A Compact Reconfigurable Coaxial Slot Antenna 8.1 Introduction 8.2 Design Principle 8.3 Simulation Results 8.4 Summary References 9 The Omnidirectional/Directional Switchable Antenna Based on the Curved Microstrip Antenna with Defected Ground Structure 9.1 Introduction 9.2 Geometry Structure and Analysis Method 9.2.1 Antenna Geometry with Defected Ground 9.2.2 Equivalent Circuit 9.2.3 Simulation Method and Experiment Condition 9.3 Result Analysis for Planar Antenna with DGS 9.3.1 Impedance 9.3.2 Length1 9.3.3 Length2 9.3.4 Cavityu 9.3.5 The Optimized Parameter Values for the Plane Microstrip Antenna with DGS 9.4 Curved Antennae 9.4.1 The Varying Principle of the Curved Antenna with Curving Angle α Changing, but Other Parameters Being Unmoved 9.4.2 Patten Varying with the Curving Angle α 9.4.3 Gain 9.5 Omnidirectional/Directional Switchable Antenna 9.5.1 Switchable Principle 9.5.2 Omnidirectional/Directional Antenna 9.6 Summary References