FIO_3_PSC__Scoping__Antenna_Wrapping.pdf

Cal OES/PSC & General Contractor Scope of Responsibilities

MW Work – CalOES, CAPSNET, and Contractor:

• MW dishes and waveguide will be purchased and delivered to the site by CalOES;

• MW dishes and waveguide are to be installed by the Contractor;

• Dehydrators and manifolds for waveguide are to be purchased and installed by the Contractor;

• Dehydrators and manifolds are to be connected to the waveguide and tested by the Contractor;

• Vault entry plates are to be purchased and installed by the Contractor, with waveguide routed through these plates and terminated appropriately;

• External ground bus items, including tower bus bars and entry point bus bars, and ground kits on MW dishes and waveguide, are to be purchased and installed by the Contractor;

• Microwave battery rack is as detailed in the Appendix is to be purchased and installed by the Contractor;

• Microwave radio equipment will be purchased and installed as a part of the appropriate year CAPSNET contract and installed by the CAPSNET contactor yet to be hired;

• Batteries for the battery racks will be purchased and installed as a part of the appropriate year CAPSNET contract and installed by the CAPSNET contactor yet to be hired;

• The turning on of the microwave radios and final path alignment of all dishes and paths will be done by the CAPSNET contractor yet to be hired.

VHF Work – CalOES and Contractor:

Note: VHF refers to all Low-Band, VHF, UHF, 700MHz, and 800MHz equipment

• Antennas and coax will be purchased and delivered to the site by CalOES;

• Antennas and coax are to be installed by the Contractor;

• Vault entry plates are to be purchased and installed by the Contractor, with coax routed through these plates and terminated appropriately;

• External ground bus items, including tower bus bars and entry point bus bars, and ground kits on antennas and coax, are to be purchased and installed by the Contractor;

Cal OES PSC Red Mtn. Project

Cal OES/PSC & General Contractor Scope of Responsibilities

• The VHF equipment battery rack as detailed in the Appendix is to be purchased and installed by the Contractor;

• The batteries for the VHF equipment battery rack will be purchased and installed by CalOES;

• The turning on of the VHF radios will be done by CalOES;

• The coax between the lightening arrestor and the rack space location will be purchased and installed by CalOES;

• The site vault transmitter combiner/receiver multi-coupler systems will be purchased and installed by CalOES.

Both MW and VHF Work – CalOES and Contractor:

• Cable trays in the vault are to be purchased and installed by the Contractor;

• Plywood to hold MDF frames are to be purchased and installed by the

Contractor;

• MDF frames and blocks are to be purchased and installed by CalOES after acceptance of the vault;

• Internal ground bus wiring will be purchased and installed by CalOES after acceptance of the vault;

• Empty seismic rated racks as detailed in the Appendix for all rack spaces will be purchased and installed by the Contractor.

OES/PSC Antenna wrapping, installation and testing guidelines Page 1

ATTACHMENT 1 – INSTALL, Heliax and Waveguide

FOR ANTENNA-JUMPER CONNECTIONS/PIG TALES (RG 214)

Shrink Wrap: https://www.commscope.com/catalog/tools_accessories/product.aspx?id=25

Products Used: Cold Shrink Kit (Commscope 245171), ¼” UV rated blue zip ties (Panduit PLT4H-TL76).

Installation:

Step 1 – Follow the Cold Shrink manufacture installation instructions.

Step 2 – Place cold shrink over antenna-jumper connectors, so that the inner plastic tail exits away from the antenna.

Step 3 – As you pull the tail, ensure that the top of the cold shrink is placed up against the antenna, to maximize protection. Pull tail 2-3 wraps at a time, ensuring that the wrap shrinks down along the curves of the connector underneath.

Step 4 – Place one zip tie near the antenna end of the wrap, and another about ½” from the jumper end. Tighten both until they depress enough to ensure a full seal.

Note: RG 214 jumpers at antennas shall be 18 to 24 inches in length.

FOR ANTENNA JUMPER TO 7/8” HELIAX CONNECTIONS

Products Used: Cold Shrink Kit (Commscope 245171), tape,1/4” UV rated zip ties

Installation:

Step 1 – Follow the Cold Shrink manufacture installation instructions.

Step 2 – Place one zip tie at each end of the Cold Shrink and one in the middle.

GROUNDING KITS (COMMSCOPE UNIVERSAL UG 12158-1584T OR 7/8 SG78-12B2U):

Universal ground kits work well, but the ones design for the manufacture of the cables function at a higher level. It is recommended that the ground kit be purchased from the cable manufacture for best performance.

Location and Orientation:

All grounds will need to be attached to the coax or WG with the ground cable pointing away from the connectors towards the ground. If the ground cable has to make bends, maintain a minimum 6" bend radius. From point of contact with the cable, the tail must always follow a path downward to its ground connection point.

VHF cable runs less than 100' above the base of the tower have one ground placed just after connector, one ground at the base of the tower, one at the feed through plate (FTP), and a polyphaser at the connection inside the vault. Runs that are above 100' have an additional ground 50' below first ground at the top. If runs above 100' are going through a monopole place the additional ground where cable exits the monopole.

https://www.commscope.com/catalog/tools_accessories/product.aspx?id=25

OES/PSC Antenna wrapping, installation and testing guidelines Page 2

MW. WG runs less than 100' with a horizontal run to the back of the dish ground just past the first sweep where the WG first meets the cable ladder. If the run is vertical to the MW dish the ground should be placed below the flex connection. Ground at the base of the tower and the FTP. Runs over 100' or through a monopole have the same grounding practices as VHF.

Run all cable runs on the inside of the tower to protect the cable and allows for all sides and corners of the tower to be used for antennas. Cable trays from tower to building install cables on the underside to protect the cable. All cable trays need to have covers and go directly to the FTP in as straight a line as possible. The orientation of MW and VHF is important to match the side of the FTP to equipment in vault. Cable tray height is important, in that it is extremely difficult to dress cables when you cannot reach the cable from ground level.

Note: Heliax and Waveguide must be a continuous run into the vault. Waveguide will terminate at the specified equipment rack. Heliax will enter the vault and extend 36 inches at termination.

Cushions/Donuts:

Always 4 hole, always 7/8”, plugs. Advantage is future expansion, disadvantages.

Cushions 7/8 SR784-K 4-holes, SR783-K 3-holes, SR782-K 2-holes, SR782 1-hole.

Cushion hardware 3/8 stainless steel-washer flat SS38FW, washer lock SS38LW, nut SS38NUT.

PSC recommendations is 4-hole cushions on all runs for expansion purposes.

Shrink Wrap: https://www.commscope.com/catalog/tools_accessories/product.aspx?id=25

CABLE IDENTIFICATION

Cable runs are identified with vinyl labels (P-Touch) from a label maker (at antenna and at polyphaser) and then sprayed with clear lacquer to prevent label from coming off or fading from exposure.

ANTENNA FLEXIBLE JUMPERS

We always use a flex connection. RG214 jumpers are always used on radio antennas. They are flexible and help prevent damage to the connection with any movement that may occur. The same goes for Waveguide used on Microwave. This is especially important for when we are aligning the dish or swapping a dish, as moving a dish with waveguide directly connected can damage the connector.

https://www.commscope.com/catalog/tools_accessories/product.aspx?id=25

OES/PSC Antenna wrapping, installation and testing guidelines Page 3

ATTACHMENT 2 – ANTENNA / CABLE TESTING

OBJECTIVE FOR ALL NEW SYSTEMS

Establish a baseline set of traces of the antenna system as a whole and its individual components.

EQUIPMENT REQUIRED

Spectrum Analyzer with a tracking generator.

Return-Loss-Bridge or equivalent.

Two test coaxial cables that connect Analyzer to Bridge. Coax must be rated for test frequencies, such as RG142 B/U.

A laptop computer to transfer the trace files.

COAXIAL TESTING

Reference Traces:

A Return Loss test is a before and after test of the 50-ohm impedance match between the bridge and the device you wish to test. This is done by comparing what the spectrum analyzer trace looks like with nothing connected to the DUT port (your reference trace) compared to what it changes to with a device attached to the DUT port (your live trace).

You will setup the test parameters on your spectrum analyzer with the Return Loss Bridge connected between the Tracking Generator Output and the RF Input with nothing attached to the DUT port.

Normally your test parameters will display the entire bandwidth you are testing. For example, in Figure 1 below, a Return Loss test at a center frequency 460 MHz with a bandwidth of 20 MHz from 450 MHz to 470 MHz. This is a trace of just the Return Loss Bridge with nothing connected to the DUT port.

Figure 1

OES/PSC Antenna wrapping, installation and testing guidelines Page 4

Next, make this trace your reference. See the user guide for the spectrum analyzer you are using. See Figure 2 below.

Figure 2

Finally, connect one end of the coaxial cable to the DUT port and leave the other end of the cable unterminated. See Figure 3 below.

Figure 3

The signal entering the cable will be attenuated as it travels through to the open end of the coaxial cable. The signal will be reflected back to the bridge due to the open at the end of the cable. The reflected signal will pass through the cable in the opposite direction and be attenuated again by the same amount. The combined amount of attenuation in both directions is equal to the Return Loss measurement. The difference in dB between the reference trace and the live trace is the Return Loss measurement on the spectrum analyzer.

TESTING AN ANTENNA AND COAXIAL CABLE

In this procedure the antenna cannot be separated from the coaxial cable; so, the reference trace can only represent the Return Loss Bridge. Thus, the return loss of the coaxial cable must be added to the VSWR specification to adjust for the added return loss in the live trace.

OES/PSC Antenna wrapping, installation and testing guidelines Page 5

Note: The coaxial cable and antenna used in this procedure are the same coaxial cable and antenna used in the previous procedure. The measurements will be very close.

Find the antenna response curve on your spectrum analyzer with the return loss bridge.

Set the Center Frequency and Span for the operating range of the radio. If you are not sure, then go full span on the spectrum analyzer and look for the response dip. See Figure 4.

Figure 4

In this example, the dip at 171 MHz on the left side of the live trace will be used. See Figure 5.

Figure 5

Next, on the spectrum analyzer:

• Set the center frequency

OES/PSC Antenna wrapping, installation and testing guidelines Page 6

• Set the span to show the dip and where the trace begins to level off (goes horizontal) on both sides of the dip.

• Remove the coaxial cable from the return loss bridge.

• Set this as your reference trace.

• Reconnect the coaxial cable. The response curve on the spectrum analyzer is the result of the coaxial cable and the antenna. See Figure 6.

Figure 6

Check the antenna specification sheet for the VSWR measurement to use in your calculation. In Figure 6 the VSWR measurement from the specification sheet is 2:1.

The markers in Figure 6 represent the following:

• Marker 1 – Lowest frequency of the antenna bandwidth.

• Marker 2 – Highest frequency of the antenna bandwidth.

• Delta – The measured bandwidth of the antenna (Marker 2 frequency – Marker 1 frequency).

• Marker 3 – The best frequency response of the antenna.

• Marker 4 – The Return Loss of the coaxial Cable.

In this example the coaxial cable was not attached to the return loss bridge when the reference trace was set; so, you compensate for this by adding the return loss of the coaxial cable to the VSWR specification of the antenna. To do this you must first convert the VSWR to Return Loss (see Return Loss to VSWR Conversion Table at the end of Attachment 2).

A VSWR of 2:1 is equal to 9.5 dB of return loss.

Next, find the frequency to the left side of the dip on the curve where the trace becomes horizontal (See Marker 4). At this frequency on the curve the antenna is no longer radiating RF. The RF is being reflected back to the return loss bridge. The difference between the reference trace and the live trace is the attenuation of the signal in both directions (going to and coming back from the antenna along the coaxial cable). This is the return loss measurement of the cable.

OES/PSC Antenna wrapping, installation and testing guidelines Page 7

To find the correct return loss levels to measure bandwidth add the return loss specification of the antenna to the return loss measurement of the coaxial cable. In this example Marker 4 is measuring

1.6 dB of return loss.

9.5 dB + 1.6.dB = 11.1 Db

Markers 1 and 2 are set as close as possible to the points on the trace that are 11.1 dB lower than the reference trace.

The measurements in Figure 6 are as follows:

• Center Frequency – 171.0 MHz

• Bandwidth – 30.76 MHz @ 2:1 VSWR

• Low Frequency of the Bandwidth – 151.41 MHz @ 2:1 VSWR

• High Frequency of the Bandwidth – 182.18 MHz @ 2:1 VSWR

Compare the measurements from figure 15 to the measurements from figure 18 below:

• Center Frequency – 171.0 MHz

• Bandwidth – 31.48 MHz @ 2:1 VSWR

• Low Frequency of the Bandwidth – 151.05 MHz @ 2:1 VSWR

• High Frequency of the Bandwidth – 182.53 MHz @ 2:1 VSWR

They are very close.

OES/PSC Antenna wrapping, installation and testing guidelines Page 8

Return Loss to VSWR Conversion Table

VSWR = [1+10 (‐Return loss/20)]/[1‐10 (‐Return loss/20)]

Return Loss (dB) = ‐20 log [(VSWR‐1)/(VSWR+1)]

VSWR = (1+|Γ|)/(1‐|Γ|) Γ = (VSWR‐1)/(VSWR+1)

Mismatch Loss (dB) = 10 log(1‐Γ2) Through Power (%) = 100 (1‐Γ2) Reflected Power (%) = 100 * Γ2

Return Loss VSWR Reflection Mismatch Loss Reflected Power Through Power (dB) Coefficient, Γ (dB) (%) (%)

1 17.39 0.891 6.868 79.43 20.57 2 8.72 0.794 4.329 63.10 36.90 3 5.85 0.708 3.021 50.12 49.88 4 4.42 0.631 2.205 39.81 60.19 5 3.57 0.562 1.651 31.62 68.38 6 3.01 0.501 1.256 25.12 74.88 7 2.61 0.447 0.967 19.95 80.05 8 2.32 0.398 0.749 15.85 84.15 9 2.10 0.355 0.584 12.59 87.41

10 1.92 0.316 0.458 10.00 90.00 11 1.78 0.282 0.359 7.94 92.06 12 1.67 0.251 0.283 6.31 93.69 13 1.58 0.224 0.223 5.01 94.99 14 1.50 0.200 0.176 3.98 96.02 15 1.43 0.178 0.140 3.16 96.84 16 1.38 0.158 0.110 2.51 97.49 17 1.33 0.141 0.088 2.00 98.00 18 1.29 0.126 0.069 1.58 98.42 19 1.25 0.112 0.055 1.26 98.74 20 1.22 0.100 0.044 1.00 99.00 21 1.20 0.089 0.035 0.79 99.21 22 1.17 0.079 0.027 0.63 99.37 23 1.15 0.071 0.022 0.50 99.50 24 1.13 0.063 0.017 0.40 99.60 25 1.12 0.056 0.014 0.32 99.68 26 1.11 0.050 0.011 0.25 99.75 27 1.09 0.045 0.009 0.20 99.80 28 1.08 0.040 0.007 0.16 99.84 29 1.07 0.035 0.005 0.13 99.87 30 1.07 0.032 0.004 0.10 99.90 31 1.06 0.028 0.003 0.08 99.92 32 1.05 0.025 0.003 0.06 99.94 33 1.05 0.022 0.002 0.05 99.95 34 1.04 0.020 0.002 0.04 99.96 35 1.04 0.018 0.001 0.03 99.97 36 1.03 0.016 0.001 0.03 99.97 37 1.03 0.014 0.001 0.02 99.98 38 1.03 0.013 0.001 0.02 99.98 39 1.02 0.011 0.001 0.01 99.99 40 1.02 0.010 0.000 0.01 99.99

MICROWAVE FEEDLINE PRESSURE TESTING

JIM PRATT

APRIL 23, 2020

Microwave feedlines, connectors and antenna feedhorns are hollow devices. As such, they tend to attract and hold moisture. To alleviate this problem, feed systems are pressured with dry air at a specific pressure to keep water and other contaminants out. This is accomplished by utilizing an air source such as a dehydrator in the equipment room that ensures a constant air pressure is delivered to the antenna feed system.

To avoid this dehydrator running constantly, it is important to ensure that the feedline and feedhorn systems are air-tight at the time of initial installation. This is accomplished by performing a pressure test on the system before it is put into service.

At the connector end of the feed system in the radio shelter, there is a small neoprene hose connected from that connector to a manifold on the shelter wall inside. A typical manifold is a Commsope 6600D, which provides four ports of antenna connection, along with valves for each port and a pressure indicator for each port. Here is a photo of such a device:

In a normal configuration, all feedlines would be connected to this manifold, one per port. If more than four ports are needed, additional manifolds are added in a “daisy chain” configuration. A source of air from the dehydrator is then connected to the manifold to maintain pressure. (The dehydrator is set to a constant value, usually 5 pounds per square inch (PSI), and starts automatically to maintain that pressure at the manifold inlet.)

To do a pressure test, before connecting the dehydrator but after all the feedlines are connected to the manifold, the valves to the connected waveguides are opened fully. A source of air (usually a nitrogen tank or a bicycle pump) is attached the manifold inlet (where the dehydrator would connect in the future). Air is then injected until each pressure gauge per connected feedline shows it has 5 PSI of pressure. Once a feedline shows it has 5 PSI, the valve to that feedline is closed. This continues until all connected feedlines show they are at 5 PSI and have their corresponding valves closed. The air source is then shut off and disconnected.

The then pressured, closed system is then left for a period of 48 hours, untouched. A technician then returns to the site to ensure that each feedline pressure gauge still shows 5 PSI. If a feedline does still show 5 PSI, that feedline system is deemed “leak free”. If the pressure has reduced below 5 PSI over that 48 hour period, the feedline system is assumed to have a leak. That leak must then be found and patched. Once patching is complete, the 48 hour test is performed again, until the entire system has been deemed “leak free”.

Once the entire system is deemed “leak free”, the temporary air source remains disconnected and the dehydrator is connected to the manifold instead for permanent operation.

OES/PSC Antenna wrapping, installation and testing guidelines Page 9

ATTACHMENT 3 – ANTENNA WRAPPING PROCEDURE

Step 1: Place antenna on cradles attached to equal-height sawhorses, attach crank to connector end.

Step 2: Clean antenna with alcohol and a lint-free towel, mark location of tuning skirt if used.

OES/PSC Antenna wrapping, installation and testing guidelines Page 10

Step 3: Cut 3” wide Teflon tape at an angle that will allow 0.5” of overlap when wrapped around the antenna. Carefully wrap around the antenna once, fully covering the end of the tape.

OES/PSC Antenna wrapping, installation and testing guidelines Page 11

Step 4: Slowly turn the crank while keeping steady tension on the Teflon tape to prevent air bubbles from forming. If air bubbles form back off about a half turn, then slowly crank forward while gently rubbing the tape as it adheres. Continue to wrap the antenna maintaining 0.5” of overlap.

Step 5: When you reach the top of the lower section of the antenna, cut the tape perpendicular to the axis of the antenna, and wrap it around making an even edge around the circumference.

OES/PSC Antenna wrapping, installation and testing guidelines Page 12

Step 6: Cut a piece of 4” diameter heavy shrink tube about 1” wide and use a very hot heat gun to shrink it over the end of the tape. Do not cover the bolts.

Step 7: Repeat steps with 2” wide Teflon tape and 2” diameter shrink tube on the top section of the antenna. Do not block hex bolts at the tip.

END OF SECTION