Marine Antenna Installations IBEX 2011 Speakers: David Gratton- - - PowerPoint PPT Presentation

IBEX 2011

Speakers: David Gratton- Martek-Palm Beach, FL Johnny Lindstrom- Westport Shipyard, WA

Marine Antenna Installations

Property of the NMEA. Shall not be copied or re-distributed.

Seminar Overview

• Antennas

– AIS, Cellular, Radar, Satellite, SSB, VHF, WX

• Location

– Aesthetic vs. Practical vs. Customer Requests

• Testing
• Installations

Antenna Basics VHF, SSB, AM/FM, AIS, Cellular

• Any Conducting Material Will Work as an

Antenna on Any Frequency

• Only Reason for Specific Antennas Is to

Control Radiation Pattern (n/a for SSB on most

vessels)

– Total Radiated Power Is Same

• Focused Radiation Pattern Results in Antenna

“Gain” (n/a for SSB on most vessels)

• Example: Spot light vs. Flood light (n/a for SSB)

Property of the NMEA. Shall not be copied or re-distributed.

Antenna Locations VHF, SSB, AM/FM, AIS, Cellular

• Objectives:
• Preserve Antenna Aperture
• Avoid Co- and Cross-channel Interference
• Avoid Shadowing Potential Services
• Avoid Damage from High-power Transmitters
• It is not possible to locate all antennas in
• ptimum locations. Most all installations are

a compromise.

Property of the NMEA. Shall not be copied or re-distributed.

• GPS, Satellite & Cell Antennas must be outside Radar

Beam

• GPS Antennas below SATCOM Antenna Beam
• Cell Transmissions Can Interfere with GPS Reception
• Multiple Radar Antennas at Different Heights (18”)
• Sat TV Spacing Dependent on Radar Output Power

Antenna Spacing Important Notes

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Antenna Spacing (Feet)

VHF GPS SSB Radar Cell Sat TV VHF 4 3 3 2 2 3 GPS 3 1/2 4 (a) 5 (c) 3 SSB 3 4 10 4 2 4 Radar 2 (a) 2 2 1 4 Cell 2 5 (c) 2 1 1 4 Sat TV 3 3 4 4 4 6

Property of the NMEA. Shall not be copied or re-distributed.

Antenna Types

Application Description T or R Type VHF Communication T/R Dipole Sideband (SSB) Communication T/R Marconi AM/FM Entertainment R Dipole AIS Vessel Tracking R Dipole Cellular Communication T/R Dipole GPS Navigation R Micro strip Satellite Comm. Communication T/R Parabolic Satellite TV Entertainment R Parabolic Radar Collision Avoidance T/R Reflector Weather Environment R Micro strip

Antenna Locations

Antenna Locations

Radiation Pattern Example VHF, AM/FM, AIS, Cellular

90 30 45 60 75 15

3D View Top Down View

Property of the NMEA. Shall not be copied or re-distributed.

High & Low Gain Patterns

Low Gain High Gain

Antenna Gain VHF, AM/FM, AIS, Cellular

• Measures the Ability to Focus Existing RF

Energy (spot light vs. flood light)

• Measure Is in dB, a Ratio of

– Maximum Radiated Power to the Radiated Power

• f an Isotropic Source (dBi)

– Maximum Radiated Power to the Radiated Power

• f a ½ Wavelength Dipole (dBd)

Property of the NMEA. Shall not be copied or re-distributed.

Aperture Disturbances VHF, SSB, AM/FM, AIS, Cellular

• Aperture Size Is a Function of Wavelength

– VHF @ 156.800 MHz, Dipole Aperture ≈ 1.6 Feet – Applications at 1+ GHz, Dipole Aperture << 1 Foot

• Antennas with Dipole Apertures

– VHF, AIS,Cell Phone, AM/FM, DGPS

• Conductors within Aperture Change Antenna

Characteristics

Property of the NMEA. Shall not be copied or re-distributed.

Antennas- VHF & SSB

• Physical Support

– Withstand 10 Lbs. Force 24” from the Mounting – How do we measure? – Two-point Mount for Antennas Longer Than 8’

• Arrangement

– Maximize Spacing to Minimize Interference

• Safety

– SSB Shock Hazard due to high voltage – Radar Radiation Hazard

Property of the NMEA. Shall not be copied or re-distributed.

VHF Test Parameters

Test Measurement Nominal Value Tolerance 1 RF Forward Power 25 Watts ≥ 20 Watts 2 RF Reflected Power at DUT Output 0 Watt ≤ 3 Watts 3 Voltage at DUT Input 13.6 Volts ≥ 12 Volts DUT= Device Under Test

Property of the NMEA. Shall not be copied or re-distributed.

Antenna Requirements-SSB

• Antenna Starts at Antenna Coupler Ground

– Signals from Lead-in Wire Should Not Be Blocked

• r Shunted to Ground
• Ideally, Antenna Is ¼ Wave Length

– At 2 MHz Antenna Would Be 120 Feet – At 22 MHz Antenna Would Be 11 Feet – Obviously not practical

• At ¼ Wave Length, RF Signal Resonates on

Antenna, Resulting in Maximum Radiation for a Given Power Level

SSB Installation

• Ground System Complexity

– Hull Material: Metal Hulls Are an Excellent Antenna Counterpoise – Salt Water Is More Conductive Than Fresh Water – Much more “effective area” is required in fresh water

• Ground Conductors

– Surface Area Is Important – RF travels on surface, not conductor – Copper Straps and Copper Tubes (hydraulic tubing) Have Greater Surface Area for a Given Weight

Property of the NMEA. Shall not be copied or re-distributed.

SSB Test Parameters

Test Measurement Nominal Value Tolerance 1 RF Forward Power 150 Peak Watts ≥ 120 Peak Watts 2 RF Reflected Power at DUT Output 1 Watt ≤ 5 Watts 3 3 Voltage at DUT Input 13.6 Volts ≥ 12 Volts Signal strength meter required to measure antenna output

Radar Location

• Beam Is Above Crew Spaces
• No Obstructions on Critical Azimuth Bearings
• Power density?

Radar Transmits a Focused Energy Beam That Can Be a Hazard to Humans and Other Receiving Equipment

Radar Mounting

• Consider Weight of Unit vs. Strength of

Location

– Many Fiberglass Arches Won’t Support Open Array Radar Units without Reinforcement

• Optimum Attitude Level with Horizon When

Cruising

– Powerboats: 2° Down at Rest or Horizontal ± 2° at Cruise – Sailboats: Horizontal ± 2°

• Vertical Height Within 30’ of Water Level to

Avoid Missing Close in Targets (discuss)

Property of the NMEA. Shall not be copied or re-distributed.

Radar Connections

• Cable between Display and Array Unit Performs

Multiple Functions

– Longer Lengths Are Available from Manufacturer – Best practice is to use Manufacturer Approved Extension Cables when required, instead of splicing

• Use Shielded Power and Communications Cables
• Ground Units to RF ground bus to Reduce EMI

Property of the NMEA. Shall not be copied or re-distributed.

Wind & Weather Sensors

• Must be installed in 360° “Clean Air”

– This assures wind & temperature readings will be accurate. – Check alignment placement (differs with manufacturers).

• Mast installations:

– Mount at top (power or sail).

• Hardtop installations:

– Mount at least 1 ft. above, and 3’ back from front of hardtop.

• Radar Arch installations:

– Mount at least 1 ft. above arch.

Property of the NMEA. Shall not be copied or re-distributed.

Wind & Weather Sensors: Dead Air Zone

Satellite Constellation Geometry

• Geostationary – Always in Same

Relative Position in Sky.

TV, Communications, Weather 22,000 miles

• Non-stationary – Cross from

Horizon to Horizon while in use.

Height varies with purpose.

• Low Earth Orbit (LEO)

400-1200 miles

• Medium Earth Orbit (MEO)

12,000 miles (GPS)

• Some Systems Must Maintain a

Minimum of 2-3 Satellites in View at All Times

Satellite System Antenna Types

• Wide Variety of Marine Communication Needs
• Receive Only

– GPS, Weather, TV, Other Entertainment

• Transmit/Receive

– Voice/Fax – Internet Data Services – Video Conferencing

• Motion Compensated Systems

Property of the NMEA. Shall not be copied or re-distributed.

GPS Antenna Installations

• Must have a clear view of the sky
• Must be outside Radar Beam, either above or below
• Should be below SATCOM Antenna Beam
• Cell Transmissions Can Interfere with GPS Reception

Property of the NMEA. Shall not be copied or re-distributed.

Typical Satellite System

Above Deck Below Deck

Interface is dependent on Satellite Dome & System

Satellite Dome Location

• Physically Secure Location
• Communications are Line-of-sight

– Clear View of as Much Sky as Practical

• Follow Antenna Spacing Requirements
• Outside Any Radar Array by 6 Feet

Property of the NMEA. Shall not be copied or re-distributed.

Multi-path Interference

• Paths Arrive at Different Times
• Received Signal is Summation of

All Signals Received

Direct Echo 1 Echo 2 Signal

Property of the NMEA. Shall not be copied or re-distributed.

Orientation and Location

Antenna Unit Antenna Unit

O X

° 15

Antenna Unit Antenna Unit

° 15

Antenna Unit Antenna Unit

O X

Flat Surface No Obstacles

Property of the NMEA. Shall not be copied or re-distributed.

Effect of Misalignment

• Misalignment Moves Predicted Satellite Position

– 30 Second Normal Search Time – 2 to 5 Minute Search Time when Misaligned – Systems with both position & heading inputs are typically faster

45 °

Line-of-Sight

• 15° to

+85° Blocked From View! Mast or Cabin Structure

• 15° to

+115°

Property of the NMEA. Shall not be copied or re-distributed.

Satellite Dome Radar Clearance

±15°

• Average Radar Antenna has a vertical

beamwidth of ±20°

±10°

System Grounding

• 10 AWG or larger

Ground wire

• Connect dome and

Control Unit to RF Ground

• Run wire to Local RF

Ground Bus

Property of the NMEA. Shall not be copied or re-distributed.

Summary

• Antenna characteristics are determined by

physical construction

• Practical Considerations Drive Mounting

Locations

• Mounting options vary from vessel to vessel
• Poor location can affect antenna performance

Property of the NMEA. Shall not be copied or re-distributed.