Automated Antenna Controller

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

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

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]

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

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]

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

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.

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

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

Visual System Overview

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

8-bit Counter 4 - 74HC74 D-Flip Flops $1.44 1 - Fairchild 74HC4040 $1.02 + Board Space

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

Main PCB Layout 15

Display and Control PCB Layout 16

Whole PCB

Main Populated PCB

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

Packaging 20

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

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

SWR and Power Measurement

SWR and Power Measurement

Power Measurements

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

Frequency Division Radio Operating Frequency Frequency Into the PIC 7 MHz 26.88 kHz 10.100 MHz 39.68 kHz 14 MHz 56.82 kHz 18.060 MHz 69.44 kHz 21 MHz 81.97 kHz 24 MHz 96.15 kHz 28 MHz 119.0 kHz

Antenna Tuning Circuit Motor Control Circuit Variable Capacitor

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

Display Frequency SWR Forward / Reflected Power

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

SWR Measurements

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.

Finished Product

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

References [1]http://www.mfjenterprises.com/Product.php?productid=MFJ-1786.[Online]. Accessed: September 29, 2009. [2]http://www.mfjenterprises.com/catalog/Pages_061-080.pdf [Online]. Accessed: September 27, 2009. [3]MFJ Enterprises, INC., MFJ Super Hi-Q Loop Antenna: Model MFJ 1786/1788 Instruction Manual, 1997. [4]http://media.digikey.com/photos/Microchip%20Tech%20Photos/pic18f2520-i%20sp.JPG. [Online]. Accessed: September 30, 2009. [5] “PIC18F2420/2520/4420/4520 Datasheet”, 2008. Microchip Technology Inc. pg 326. [6]http://vk1od.net/transmissionline/VSWR/VSWRMeter.htm. Owen Duffy 1995, 2006 [Online]. Accessed: October 6, 2009. 36

Questions? 37