SOP Full Flow Antenna Installation

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Standard Operating Procedure
Subject:
SOP Full Flow Antenna Installation
Author:
Darren R. Chase
Approved by:
Don Warf

Contents

Objective

To install all parts necessary to construct an antenna to be used for PITtag detection on all Full Flow bypass pipes.

Scope

This SOP is intended for PSMFC personnel to use as a guideline to allow for PITtag detection on any full flow bypass pipe. Although pipe sizes and detection electronics may vary this SOP will assist in constructing an acceptable PITtag detection system.

Responsibilities

The installation of full flow antennas should only be performed by qualified PSMFC personnel.

Tools/Parts Required

The following tools/parts or equivalents will be required to perform this procedure.

  • 6"W X 1/2"T Closed Cell foam strips.
  • 3"W UHMW strips.
  • 1 box of Buetyl Tape.
  • Roll of double sided carpet tape.
  • 270' Rolls 16awg Teflon coated silver plated copper wire (2).
  • RF Clamps.
  • Fluke handheld LCR Meter.
  • 3"x2" project box.
  • DP 270 epoxy.
  • NPO Capacitors.
  • Perforated Circuit Board.
  • Level.



Procedure

This procedure is designed to be used as a guideline for constructing one (1) Full Flow antenna for PITtag detection. This particular antenna is a series/parallel type antenna. Two (2) antennas are wrapped and then tied together in parallel with a nominal inductance of 350uH to 400uH to be driven as one detection system. Most Full Flow installations consist of four (4) shielded antennas.

Install RF Clamps

  • The clamps are usually installed by the contractor if that is the case then they can be moved towards each of the shield walls until the antennas have been wrapped. If they have not been installed then they will need to be put on the pipe and bolted together using the proper hardware. The specifications for hardware can be found on PSMFC drawing B2J FF RF Clamp.pdf.
  • The clamps will be used to help determine the inductance and capacitor bank.
  • The final placement will be set in the Testing System of this procedure.



Antenna Cable Install

  1. Pull the Antenna cable from the transceiver enclosure into the Antenna shield.
  2. Connectorize the Transceiver enclosure end. Make sure that you leave enough slack inside the enclosure to allow for possible re-terminations if necessary.
  3. The cable inside the antenna shield does not have to be cut to length at this point.
    • A good rule is to leave enough inside the shield to work with so that it does not get in the way during the testing of the system.



Antenna Base

  1. Measure the distance between the inside shield walls to determine where the center of the pipe is located.
    • The antenna should be as centrally located as possible. This will allow the installer to utilize the RF clamps to load the antenna with out any loading coming from the shield. If necessary the antenna could be constructed closer to one side of the shield but keep in mind this will change the inductance and could have an effect on the tuning and noise.
  2. Unroll the 1/2" Closed Cell Foam (CCF) and wrap around the pipe.
    • The foam is used to allow the pipes ovality and eccentricity to change without reflecting these changes to the antenna.
  3. Measure and cut the foam so that the ends just meet.
    • Be sure to pull the foam so that it is snug all the way around the pipe but do not stretch the foam or the changes to the pipe may be reflected to the antenna.
  4. Measure and apply a second piece of CCF to the pipe as described in the steps above.
    • Once the second piece is applied to the pipe make sure that the two (2) pieces are pushed together so that the seam between them is close to the middle of the pipe inside the shield.
  5. Prepare and install two (2) pieces of UHMW template material.
    • The following steps need to be performed to prepare the UHMW strips:
      1. Cut a 6" wide pre-cut piece of UHMW down the center creating two (2) 3" wide pieces.
      2. wrap the pieces around the CCF and allow fro an overlap of about 3" and cut to length.
      3. Remove the UHMW measure and mark the piece every 8" from top to bottom.
      4. Apply double sided tape across the UHMW at each mark.
      5. Cut and apply Buetyl tape to each of the double sided tape pieces with the adhesive side up. Do not remove the backing from the buetyl tape at this stage.
      6. Cut a piece of tape and apply it to the end of the UHMW that will be the underside of the overlap.
    • You want to have at least four (4) points of adhesion to keep the wire taunt will wrapping the antenna. The more points the easier it will be to keep the wire straight and taunt.
    • Remove the backing on the double sided tape for the overlap. Wrap the Strip around the CCF and pull tight and then back it out just a little and press the top half to the bottom half. The template should spin somewhat freely on the CCF but not be so loose that there is a gap at the bottom between the CCF and the strip. If necessary you can peel the template apart and readjust it for a good fit.



Wrap Antenna

Before you begin wrapping wire onto the template material you will need to figure out how may wraps you will need on each antenna. This can be achieved by using the formula provided below:

  • Formula for determining the number of wraps on round pipe
N=sqrt of I(9R+10L)
R2

I=inductance
R=Radius
L=Length (this actually the width of the antenna)
R2= radius squared

  • You can use the template width for (L) to determine the number of wraps.
  • Since the antenna is a parallel type antenna you will have to wrap each antenna at twice the anticipated inductance that is desired. As stated at the beginning of this document you want your inductance of the antennas in parallel to be somewhere between 350 and 400uH. A good inductance to wrap to is 720uH for each antenna.
  • The antennas must be wrapped in the same direction, if they are in the opposite direction you have problems tuning and possibly create a cancellation of fields in the middle of the antenna. PSMFC standard is to wrap the wire on the pipe so that wire is wound Clockwise from upstream to downstream. The biggest key is to wrap them in the same direction.
  • After you have figured out the number of wraps needed you can calculate the amount of space to used on the 3" template. This is important because you want to try and have the upstream antenna end as close to the edge of the template material as possible. This will make it easier to space the antennas when it comes time to tune. The wire that is used has and O.D. of .089 in. this times the number of wraps will tell you the space required for the antenna.
  1. Apply the wire.
    • Remove the backing on the Buetyl tape pieces.
    • Apply the wire to the upstream template
    • you can spin the template towards you until the calculated number of wraps have been achieved.
    • Cut the wire and strip both ends.
    • Using the LCR meter measure the inductance of the antenna. You might want to note the inductance of each antenna prior to connecting them in Parallel.
  2. Apply wire to the downstream template using the same techniques described above.
    • Before making the connection of the two antennas make sure to complete the next steps.
      1. measure and space the antennas so there is 2" between the antennas. This is measured from the trialing wire of the upstream to the starting wire of the downstream antenna.
      2. Bring the RF Clamps to a measured distance of 12" from each antenna. This will have a direct effect on the inductance of the overall antenna.
  3. Place the two antennas in parallel and measure the inductance.
    • If the inductance is to high wire will need to be removed.
    • If the inductance is to low you may be required to re-wrap one or both antennas. PSMFC work ethics do not allow for any splices in antenna wire, there are to many problems that can accompany this kind of installation.
    • A quick reference would be to remove one wrap from either antenna and remeasure the parallel inductance. This will tell how much inductance is being removed with each wrap.
    • Wire should be removed from the most upstream and downstream sides of each antenna. This will help to keep the spacing between the antennas at a constant.
  4. Once the adjustments have been made to achieve a parallel inductance between 350-400uH you will need to build a capacitor bank to test the antenna.



Capacitor Bank

  1. Calculate the capacitor bank size
    • The following is a chart of inductance versus capacitance at the antenna for a FS1001A system. The chart assumes that only the bottom capacitor jumper (10,000 pF) is installed. This is only to be used as a guide and may vary slightly depending on internal antenna capacitance and environmental loading. Lower and higher inductance's can be extrapolated due to the linear nature of the chart.
    • All NPO type capacitors that are used have a voltage rating of 2KV.
    Capacitor Selection Guide
    Capacitor Selection Guide
    • This chart was developed by Destron-Fearing/Digital Angel at a time when the cable being used was about 18pf/ft. the current cable is 9pf/ft. If you have a short cable length, less than 25ft, you can still use it as a guide for the capacitance needed.
  2. Matrix selection
    • The matrix is the configuration of capacitors that will be needed to achieve the right capacitance as well as providing the correct amount of voltage protection for the transceiver.
    • The current matrix that is used for the full flow is what is known as a 2 X 5. Because of the size of most full flow pipes it is suggested that no less than a series of three capacitors be used. The graphic below will assist in the building and calculations of the matrix.
    Capacitor Matrix Guide
    Capacitor Matrix Guide
    • The legs of the capacitors can be twisted together for testing purposes. The NPO capacitors are expensive and should not be placed into the perforated board and permanently built until they have been tested with the system.
  3. Potting Bank
    • Cut Perforated Circuit board so it will fit inside the project box.
    • Place caps into the board keeping the matrix that was selected and tested.
    • Twist and solder legs together.
    • Use a piece of the antenna wire to make leads for both ends of the bank and solder them to the bank. You will want to make the leads long enough to ensure that the antenna wires can be reached when the bank is installed.
    • Before continuing it would be best to retest the bank to ensure that it has been constructed properly.
    • place bank into the project box
    • Fill the project box with DP 270 epoxy. This will need to cure overnight.
    • Mark the project box with the capacitance.



Testing System

  1. RF clamp placement
    • Adjust the clamp so that it is 12" from the antenna wire.
    • Plumb the RF clamp using the level.
    • Use the adjusting screws to center the clamp around the pipe.
    • Adjust the opposite clamp in the same manner.
  2. Antenna Spacing
    • Space the two antennas so that there is a 2" gap between the antenna wires.
  3. Capacitor Bank and cable attachment
    • Twist one side of the bank together with the White lead coming from the antenna cable.
    • The other side should be twisted together with the upstream wires on the antenna.
    • The black wire should be twisted together with the downstream wire from the antenna.
  4. Transceiver
    • Connect the antenna cable to the transceiver
    • Power on Transceiver
    • Tune transceiver. To tune the transceiver please refer to the appropriate tuning procedure. Currently there are only two transceiver types being used on the full flow detection systems the FS 1001A SOP_FS1001A_Tuning or the FS1001A-B SOP_FS1001AB_Tuning
    • To verify that the capacitor bank is correct the transceiver should have somewhere around 10,000pf of selectable capacitance in side once the system is tuned.
    • If the system cannot be tuned due to selectable capacitance i.e. need to add or subtract and do not have the capacity the cap bank will need to be adjusted. The change in capacitance is about 5:1. Every 100pf at the antenna is a result in about 500pf inside the transceiver.
    • The tuning will change slightly when the antenna and cable connections are dressed out.
    • After the system has been tested and the capacitor bank is verified to be correct proceed to the "Potting"section of the Capacitor Bank procedure.



Sealing and Tuning

  1. Seal Antennas
    • Wrap Buetly tape around the antenna to measure the amount needed.
    • Cut the tape to length.
    • Peel off backing and apply over the top of the antenna wires.
    • Repeat steps for second antenna.
    Remember to leave the antenna wires that need to be connected out of the Buetyl tape.
  2. Antenna Spacing
    • Once the wires have been sealed the antenna must be separated by 2"
    • Make sure that spacing is equal over the entire circumference
  3. RF Clamp Placement
    • Start with the upstream clamp. Set clamp to a distance of 12" from the antenna wire. You will need to check this distance at several points around the circumference of the pipe.
    • Adjust feet so that the clamp is equally spaced off the pipe.
    • Use a level to make sure that the clamp is plumb.
    • Lock down foot adjustment locking nuts.
    Be Careful after completing this task that the RF clamps do not get bumped or moved. If this happens recheck the alignment and adjust if necessary.
  4. Antenna wire and Cable Dressing
    • Select location and attachment points for antenna cable.
    • Cut cable to length and strip leaving enough wire to make clean connections to the antenna wire.
    • Select location for the Capacitor Bank.
    • Mount the Capacitor Bank with adhesive backed Velcro.
    • Connect leading antenna wires by stripping and twisting together. Make the transition from downstream antenna to upstream as straight as possible.
    • Connect trailing antenna wires by stripping and twisting together. Make the transition from downstream antenna to upstream as straight as possible.
    • Connect the black wire from the antenna cable to the downstream antenna wires using a 3M solder-splice #SS501. Shrink the waterproof shrink wrap around the connection.
    • Connect the White antenna wire to one side of the Capacitor Bank using 3M solder-splice. shrink waterproof shrink wrap.
    • Connect the other side of the Capacitor Bank to the upstream antenna wires using a 3M solder-splice.
    • Antenna installation is complete. The drawing below show what the final install should look like.

Full Flow Installation

  1. Final Tuning
    • Fine tune the transceiver using the appropriate tuning procedure.
    SOP_FS1001A_Tuning
    SOP_FS1001AB_Tuning
    • Make note of the current and noise levels.
    • Document the inductance of each individual antenna, parallel inductance, capacitor bank, antenna spacing, and RF clamp spacing.




References

B2J FF RF Clamp.pdf
SOP_FS1001A_Tuning
SOP_FS1001AB_Tuning
Full Flow Installation

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