Inverted-L and Inverted-F Antennas in Antenna Design
Explore the structures, current, radiation patterns, and benefits of Inverted-L and Inverted-F antennas for different applications, along with insights on radiation resistance and impedance matching. Learn about the advantages and considerations of these antenna types in antenna design.
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Presentation Transcript
ICE-5108084 Antenna Design Lecture 10: Inverted-L and Inverted-F Antennas 10.1 Inverted-L Antenna (ILA) Structure 10.2 ILA Current and Radiation Pattern 10.3 Various Forms of the ILA 10.4 Radiation Resistnace of the ILA 10.5 Inverted-F Antenna (IFA) Structure 10.6 IFA Size Reduction 10.7 Various Forms of the IFA 1
10.1 Inverted-L Antenna (ILA) Structure Why ILA? - To make a monopole antenna low profile: 10-25% of the monopole height - Low profile = Low height - f = 10 MHz, = 30 m, Hmonopole= 7 m, HILA= 2.1 m Pros of ILA: low profile Cons of ILA: imedance matching required + narrower bandwidth 2
10.2 ILA Current and Radiation Pattern Current on ILA and Radiation Pattern of ILA on the real Earth f f1, L 1/2 f = 2 f1, L = 1 f = 3 f1, L = 1.5 1 3
Radiation Pattern of ILA - Vector sum of fields by vertical current and horizontal current 4
10.3 Various Forms of the ILA - ILA for HF Communication on the ground - ILA for mobile NVIS communication 5
- ILA for missile telemetry - ILA variants 6
10.4 Radiation Resistance of the ILA Radiation resistance RVdue to vertial current: - Uniform current approximation: ideal dipole 2 L 2 V = 80 R rv - Monopole impedance: half the dipole impedance 2 L 1 2 2 V = = 40 R R V r Radiation resistance RHdue to horizontal current: - Short ideal dipole above the ground plane 2 2 3 L 32 L V H = (120 ) R rh 15 - Sinusoidal current dipole above the ground plane: multiply it with (2/ )^2 2 2 2 L 2 L 2 V H = = 1024 R R H rh Radiation resistance of an ILA: - Geometric sum Example: LV= 0.07 , LH= 0.15 RV= 1.9 , RH= 1.1 , RILA= 5.9 RILA= 6.6 (by CST Studio) + + 2 ILA R R R R R V H V H 7
10.5 Inverted-F Antenna (IFA) Structure Why IFA? - ILA impeance: 7 j 22 -Add an impedance-match loop structure to ILA IFA -Adjust S to make the IFA impedance be 50 . Pros of IFA: low profile + small size Cons of IFA: narrower bandwidth 8
10.6 IFA Size Reduction Meander line IFA - Reduce LHby meandering 9
10.7 Various Forms of the IFA USB dongle Bluetooth, WiFi: 2-element MIMO WiFi: Miniature dielectric chip antenna: 10
Wideband PIFA (planar inverted-F antenna) Mobile phone intenna (internal antenna) - LDS (laser direct structuring) technology for 3D antenna 11
ICE-5108084 Antenna Design Lecture 10: Inverted-L and Inverted-F Antennas 12
