1. Automated Antenna Controller

2. Motor Control Software
Our Team
Sam Bryan – Team Leader
Electrical Engineer
PCB Layout
Schematics
Brandon Gray
Electrical Engineer
Frequency Counting
PCB Layout
Dr. Raymond Winton
Academic Advisor
Jacob Edwards
Computer Engineer
Frequency Counting
Motor Control Software
Ashley Stough
Electrical Engineer
Packaging
Schematics
Sponsor

3. Outline Problem Solution Constraints Special Concerns System Overview
Technical
Practical
Special Concerns
Manufacturability
Economics
System Overview
Advancements
Testing
Packaging

4. What is the Automated Antenna Controller?
Microprocessor controlled version of MFJ Enterprises, Inc.’s user-managed loop antenna controller
Used with MFJ-1786 and MFJ-1788 Super Hi-Q Loop Antennas
[1]

5. What is the Automated Antenna Controller? (cont’d)
Unit controls a motor attached to a variable plate capacitor which adds capacitance to the impedance of the load
Standing Wave Ratio (SWR)
Ratio of power or impedance:
Power reflected to source versus power transmitted from source
Load impedance against source impedance

6. Problems with Existing Controller
Operation is Time Consuming
Unit is Difficult to Operate
Meter is Difficult to Read Accurately
Inaccurately controlled
What’s difficult to read accurately?
[2]

7. Solution Use microcontroller to allow more accurate tuning
Automate the tuning process to avoid user error
Utilize digital display to allow easier output for user

8. Technical Constraints
Name
Constraint
Frequency
Frequency must measure and display between 7 and 30MHz ± 30kHz.
Standing Wave Ratio
A maximum of 3:1 SWR must be achieved.
Connector
RF connection must be an SO-239 style connector.
RF Power
Forward and reflected power must be measured and displayed accurately to ± 1W.
Power Supply
Power supply must be the MFJ-1312D AC adapter.

9. Health and Safety Enclose the controller Prevent electric shock
Prevent burns from hot components
Prevent RF burns

10. Economics: Manufacturing Cost
Parts must already be in stock at MFJ
Reduces number of parts ordered
Limits design options

11. Visual System Overview

12. Revisions from SD1 D-Flip Flops to 8-bit Counter User Control
Fine Tune Buttons
PCB
Packaging

13. 8-bit Counter 4 - 74HC74 D-Flip Flops $1.44
1 - Fairchild 74HC4040 $ Board Space

14. User Control & Fine Tune Buttons
User Override Button
User Fine Tune
Tune Up
Tune Down

15. Main PCB Layout 15

16. Display and Control PCB Layout16

17. Whole PCB

18. Main Populated PCB

19. Display and Control PCB
LCD
Power Button
User Fine Tune Button
Tune Up and Tune Down Buttons
Ribbon Cable

20. Packaging 20

21. Bill of Materials Total Electronics Cost = $39.85
PCB Mass Produced
Total Electronics Cost – Hbridge = $22.07
Total Packaging Price = $10.33
Total Price = $50.18

22. Testing Subsystem Testing System Testing SWR and Power Measurement
Frequency Measurement
Antenna Tuning Circuit
Display
System Testing

23. SWR and Power Measurement

24. SWR and Power Measurement

25. Power Measurements

26. Frequency Measurement
8 Bit Counter Input
8 Bit Counter Output
8 Bit Counter Input / 256 = Counter Output to the PIC

27. Frequency Division Radio Operating Frequency Frequency Into the PIC
7 MHz
26.88 kHz
MHz
39.68 kHz
14 MHz
56.82 kHz
MHz
69.44 kHz
21 MHz
81.97 kHz
24 MHz
96.15 kHz
28 MHz
119.0 kHz

28. Antenna Tuning Circuit
Motor Control Circuit
Variable Capacitor

29. Antenna Tuning Circuit
Fast Tune and Slow Tune
No feedback from Motor
Tune Down the Antenna to the lower limit
PWM Input
H-Bridge Output

30. Display
Frequency
SWR
Forward / Reflected Power

31. System Testing Testing with the Dummy Load
Testing with the Loop Antenna

32. SWR Measurements

33. Product Performance Technical Constraint Constraint Met
Frequency must measure and display between 7 and 30MHz ± 30kHz.
Yes
A maximum of 3:1 SWR must be achieved.
RF connection must be an SO-239 style connector.
Forward and reflected power must be measured and displayed accurately to ± 1W.
Power supply must be the MFJ-1312D AC adapter.

34. Finished Product

35. Outline Problem Solution Constraints Special Concerns
Technical
Practical
Special Concerns
Manufacturability
Economics
Parts and Revisions
Testing
Subsystem testing
System testing

36. References
[1] Accessed: September 29, 2009.
[2] [Online]. Accessed: September 27, 2009.
[3]MFJ Enterprises, INC., MFJ Super Hi-Q Loop Antenna: Model MFJ 1786/1788 Instruction Manual, 1997.
[4] [Online]. Accessed: September 30, 2009.
[5] “PIC18F2420/2520/4420/4520 Datasheet”, Microchip Technology Inc. pg 326.
[6] Owen Duffy 1995, 2006 [Online]. Accessed: October 6, 2009. 36

37. Questions? 37