antenna project esp2110 design project
DESCRIPTION
Final Presentation for ESP Design Project 2110TRANSCRIPT
ESP2110WIFI ANTENNA DESIGN PROJECT
Picture from [1], p. 353
ContentsIntroduction1. Fabrication, design and parts
2. Reason for choice
Theory3. Loop
4. Archery-target antenna
5. Impedance matching
6. VSWR
User design and future considerations
Performance analysis
Field testing
Conclusion
Credits
Introduction
FabricationArchery target antenna
Parasitic elements Main back reflector Front annular reflector Center small reflector Wooden back base for physical support
Driven element Z-shape 1λ circular loop
Design overview
Basic design and dimensions from existing literature
Optimum dimensions derived mainly from experimentation and occasionally FD-TD method
Modifications not tested before include
1. the addition of secondary rim
2. use with specified driven element
Picture modified [2], p. 227
Back Reflector
Front + center reflector
1λ circular loop
Introduction
Reason for choice Good match with project
requirement
Relatively small size for its Performance
Flexibility with modifications : type of driven element used configuration of reflectors
Characteristics required
Archery-target
Antenna
High gain √
High directivity √
Fixed, narrow band
√
WIFI frequency band
√
Loop theory
1λ circular loop
Radiation pattern
Pictures modified from [3]
4:1 delay line type coax Balun 1λ loop feedpoint impedance (Ω) ≈ 80-150 L = 1/2λ
Causes 180° phase shiftas desired
Provides balanced input
Balun theory
Pictures from [5] and [6]
Endoresonance antenna: open cavity Can be considered similar to
waveguide operation (resonant modes)
Archery-target antenna theory
Pictures from [1], p. 19
Archery-target antenna theory
Influence of sub-reflector size
Small
Large
Pictures modified from [7], p. 4
Archery-target antenna theory
Evolution of front reflectors
Maintaining backfire effect while enlarging aperture size
Increasing directivity with secondary rim on reflectors
Archery-target antenna theory Estimated radiation plot and
directivity
Graphs from [2], p. 226
Impedance matching
Determine lengths x1 and x2 using software Smith v3.10
Smith chart and VSRW of antenna with original 1λ line segment
Impedance matching
Practical approach to impedance matching
Since Smith chart of antenna line segment is favourable
And accuracy loss due to connectors and small physical length of λ
Take x1 ≈ 0
Impedance matching
Impedance matching
New Smith’s Chart and VSWR with stub
User design & future considerations
User design Handle/ portable Rigid back wooden support Weather resistant due to lacquered wood
Future considerations Selective frequency using translucent aperture Increase aperture efficiency by using better dielectric Wider bandwidth using main conical
reflector and a smaller centre reflector
Pictures from [8], p. 115
Performance analysis
-80
-60
-40
-20
0
20
40
60
80
100
120
RSSI
signalQuality
2m
• RSSI -10 to 15• Signal Quality 100
25m
• RSSI -50• Signal Quality 80
2m
• RSSI -10 to 15• Signal Quality 100
Loop A (Directed)
Loop A
Loop B
Loop B (Opposite)
2m
• RSSI -35• Signal Quality 100
25m
• RSSI -58• Signal Quality 80
2m
• RSSI -37• Signal Quality 97
Field hunting
Field hunting – Objective A
Field hunting – Objective A
Field hunting – Objective B
Field hunting – Objective B
Field hunting – Objective C
Field hunting – Objective C
Field hunting - Summary
Conclusion
Fabrication Our antenna is durable and portable Well suited for the Objective
Overall Performance Up to standard for field testing Good Signal Quality
References and Credits [1] A. Kumar, H.D. Hristov, Microwave cavity antennas , Norwood, MA :
Artech House , 1989 [2] M. Vidmar, “An Archery-Target Antenna”, Microwave Journal, Vol.
48, No. 5, pp.222-230, May 2005. [3] J. Bernhard, E.Michielssen and L. C.Godara, Eds., “Antenna
Parameters, Various Generic Antennas and Feed Systems, and Available Software”, in Handbook of antennas in wireless communications , Boca Raton, FL : CRC Press, 2002, ch. 5, sec. 3.2
[5] T. Tribuzio. (2011, Mar. 2). About Balun [Online]. Available: http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=3767
[6] A. Vernucci. (2011, Mar. 2). A Simple 50-ohm Single-Band Balun [Online PDF]. Available: www.qsl.net/i0jx/balun.pdf
[7] M. Rayner, A.D. Olver, A.D. Monk, “FD-TD design of short backfire antennas”, IEE Proc.-Microw. Antennas Propag., Vol. 144, No. 1, pp. 1-6, Feb 1997
[8] G. S. Kirov, “Design of Short Backfire Antennas”, IEEE Antennas Propagat. Mag., Vol. 51, No. 6, pp. 110-120, Dec 2009