thursday, september 22, 2005 part ii – am antenna …00 am transmitter characteristics panel ... +...

1

AM Directional Antennasin a Digital World

2005 NAB Radio ShowPart 2 – AM Antenna Systems

and HD RadioEnd12:00 PM

All Questions and Answers11:30 PM

Hardy/Hinkle/Mendenhall

Transmitter Characteristics Panel11:00 AM

Break10:30 AM

Cox/WarnerWhere the Bandwidth Meets the Load10:00 AM

RackleyTransmitter Load Optimization for HD Radio9:30 AM

DawsonEvaluating Antennas for HD Radio9:00 AM

RackleyDA System Design Considerations for HD Radio

8:40 AM

DawsonDA Pattern Design Considerations for HD Radio

8:20 AM

RackleyModulation Basics8:00 AMX

Part II – AM Antenna Systems and HD Radio

Thursday, September 22, 2005

Modulation Basics


and HD Radio

Antenna Performance Concerns

• Unnecessarily High Digital-to-Analog Crosstalk (Hiss and “Bacon Frying” Sound)

• Decreased “Robustness” of Digital Signal • Digital Coverage Area Limited by Pattern

Bandwidth• Higher Adjacent Channel Interference Resulting

from Poor Pattern Bandwidth• Noisier Analog Reception in DA Null Region Due

to Poor Pattern Bandwidth

2

AM Equation AM Equation Expansion

F(C)F(C) - F(M) F(C) + F(M)

AM SINUSOIDAL MODULATION SPECTRUM(FREQUENCY DOMAIN)

F(C)

F(C) - F(M) F(C) + F(M)

AM SINUSOIDAL MODULATION(VECTOR REPRESENTATION)

3

F(C)

F(C) - F(M) F(C) + F(M)


R

F(C)

F(C) - F(M) F(C) + F(M)


R

F(C)

AM COMPLEX MODULATION(VECTOR REPRESENTATION)

AND ETC.....

FREQUENCY COMPONENTSOF

MODULATING W AVEFORM

F(C)

AM COMPLEX MODULATION SPECTRUM(FREQUENCY DOMAIN)

4

FM Equation FM Equation Expansion

F(C) + F(M)

F(C)F (C) - F(M)

FM - PM MODULATIONFIRST ORDER SIDEBANDS

AM + DIGITAL IQ MODULATION

1 0 1 1

0 0 1 0

0 1 1 1

1 0 0 1

CONCEPTUAL ONLY - NOT TO SCALE

CARRIER

100% POSITIVE PEAK

DIGITALINFORMATION

5

F(C)

AM IBOC MODULATION SPECTRUM(FREQUENCY DOMAIN)

CONCEPTUAL - NOT TO SCALE

+J 1.0

-J 1.0

J=0.0

R=1.0

0 DEGOR

180 DEG

45 DEG

90 DEG

135 DEG

TOWARD GENERATOR

SMITH CHART BASICS

FINAL AMPLIFIER LOAD IMPEDANCE SYMMETRY

F(C)

F(L)

F(H)

F(C)

F (C) - F(M)

SIDEBAND ALTERATIONFROM SYMMETRICAL LOAD

F(C) + F(M)

6

FINAL AMPLIFIERLOAD IMPEDANCE ASSYMMETRY

F(C)

F(L) F(H)

R

+X

-X

F(C)

F (C) - F(M)

SIDEBAND ALTERATIONFROM ASYMMETRICAL LOAD

F(C) + F(M)

End12:00 PM




Break10:30 AM





8:40 AM


8:20 AMX




DA Pattern Design Considerations for HD Radio


and HD Radio

7

Pattern Design

Current distribution and radiation

8

How a horizontal pattern is created

9

AM Antenna Pattern Design

Self Impedance + Coupled Impedance = Operating Impedance

RMS = Pattern SizeRSS = (E1

2+E22+..+En

2)½

If E values are largesystem is “sensitive” to small % changes

If E values are smallsystem is more stable and has less change with frequency (sidebands)

10

Parameter Inversion

• Original Parameters• Tower 1 = 1/0 Tower 2 = 0.5/55

• Inverted Parameters• Tower 1 = 0.5/-55 Tower 2 = 1/0

Pattern Inversion Showing Geometry Inversion

12

End12:00 PM




Break10:30 AM





8:40 AMX


8:20 AMX




DA System Design Considerations for HD Radio


and HD Radio

Typical DA Feed SystemNodal Modeling of Complete

System

• Necessary to Calculate System Network Effects and Tower Operating Impedances Simultaneously

• Most Existing Systems Were Designed Without Nodal Modeling

13

Nodal Modeling

• Uses Admittance Matrix to Represent Tower Self and Mutual Characteristics – Usually From Moment Method Modeling

• Includes Nodes for Common Point, Tower Bases, Transmission Line Ends, and at All Branch Connections

Broadbandingby Optimizing System Phase

Shift• Select Overall Phase Shift Scheme (Phase

Budget) That Allows Base Impedance Sideband Excursions to Compensate One Another

• Iterate Basic, Low-Q Network Design for Different Phase Shifts Using Nodal Model

Reference DA Feed System Pattern Bandwidth Reference

14

Pattern Bandwidth + 1 Increment Phase Shift

Pattern Bandwidth+2 Increments Phase Shift

Pattern Bandwidth + 3.5 Increments Phase Shift DA Feed System

15

Textbook Diplexer System Calculated Input Impedance (Red)

Improved Diplexer System Calculated Input Impedance (Blue)

16

Best Diplexer System Best Diplexer System

Best Diplexer System 1330 KHZ Best Diplexer System 1410 KHZ

17

Conclusion

• In Addition to Minimizing Circuit Q, Overall System Phase Shift Optimization is Desirable for DA Systems

• Diplexer and Filter Circuits Must Be Optimized for Complex Impedance of Load

• New Equipment is Not Necessarily HD-Radio Compatible End12:00 PM




Break10:30 AM



DawsonEvaluating Antennas for HD Radio9:00 AMX


8:40 AMX


8:20 AMX




Evaluating Antennasfor HD Radio


and HD Radio

Evaluating Antennas

18

Ibiquity Desired Characteristics

• +/- 5 KHz – RF Final Amplifier Load Impedance Symmetry Such That VSWR of One Sideband Impedance Does Not Exceed 1.035:1 When Normalized to the Complex Conjugate of the Corresponding Sideband Impedance on the Other Side of Carrier Frequency

• (Hermitian Symmetry)

Symmetry Desired for IBOC(Conjugate Impedances at +/-5 KHZ)

- 5 KHz

+5 KHz

R

+X- X


• +/- 10 KHz – RF Final Amplifier Load Impedance VSWR Not Exceeding 1.20:1

• +/- 15 KHz – RF Final Amplifier Load Impedance VSWR Not Exceeding 1.40:1

VSWR Desired for IBOC

1.4:1 V SWR

1.2:1 VSWR

Fc

+10 KHz

-15 KHz

R

+X-X

19

VSWRs of Existing DAs(Random Sample of 50)

20 30 40 5010 60 70 80 90 1000PERCENTILE RANKING

1.0:1

1.2:1

1.4:1

1.6:1

1.8:1

2.0:1

2.2:1

2.4:1

2.6:1

2.8:1

3.0:1

VSW

R+/

-10

KHZ

20


• +/- 15 KHz – Response From Transmitter to Far Field within +/- 2.0 dB

• +/- 15 KHz – Group Delay Constant Within +/-5.0 Microseconds(or Phase Response < 27° across 30 kHz Bandwidth)

Network Analyzer Measurements

Input Impedance Measurements(Nondirectional Antenna ATU/Diplexer)

Transmitter Load Impedance(Feeding ATU/Diplexing Filter)

21

High Power Network Analyzer System

AMPLIFIER(+50 dB)

DIRECTIONALCOUPLER

ATTENUATOR(-20 dB)

ATTENUATOR(-20 dB)

ATTENUATOR(-12 dB)

DUTRF OUTPUT

RECEIVER R

RECEIVER A

RECEIVER B

VECTORNETWORKANALYZER

REF(-30 dB)

FWD(-30 dB)

0 dBm(0.22 V)

+50 dBm(70.7 V)

+38 dBm(17.7 V)

DA Parameter System

AMPLIFIER(+50 dB)

DIRECTIONALCOUPLER

ATTENUATOR(-20 dB)

ATTENUATOR(-20 dB)

ATTENUATOR(-12 dB)RF OUTPUT

RECEIVER R

RECEIVER A

RECEIVER B

VECTORNETWORKANALYZER

FWD(-30 dB)

ATTENUATOR(-20 dB)

CP

REFERENCETOWER

CURRENTSAMPLE

DATOWER

CURRENTSAMPLES

22

Measured Tower Ratio Measured Tower Phase

23

Pattern Bandwidth Evaluation for IBOC Performance

• Observe Tower Current Ratios and Phases at Carrier and Sideband Frequencies

• Excite Moment Method Computer Model of Array to Produce Sideband Parameters

• Calculate Relative Magnitudes and Phases of Far-Field Radiation at Different Azimuths Around the DA Pattern and Compare to IBOC Requirements

AZIMUTH

(Degrees True)

-15 KHz RESPONSE (dB)

+15 KHz RESPONSE (dB)

+/- 15 KHz DEVIATION FROM

LINEAR PHASE (Degrees)

0 +2.2 -11.2 17.1 10 +1.1 -3.1 1.6 20 +0.3 -1.4 0.1 30 +0.1 -0.7 0.5 40 0.0 -0.2 0.5 50 -0.1 +0.1 0.6 60 -0.1 +0.2 0.5 70 -0.2 +0.3 0.6 80 -0.2 +0.4 0.6 90 -0.2 +0.4 0.5 100 -0.2 +0.4 0.6 110 -0.2 +0.3 0.6 120 -0.1 +0.2 0.5 130 -0.1 +0.1 0.6 140 0.0 -0.2 0.5 150 +0.1 -0.7 0.5 160 +0.3 -1.4 0.1 170 +0.7 -3.1 1.6 180 +2.2 -11.2 17.1 190 +7.0 +4.3 82.1 200 +3.7 +4.6 11.9 210 +3.0 +2.6 0.4 220 +4.4 -0.2 4.1 230 +5.4 -4.6 9.1 240 +2.8 +0.9 1.8 250 +1.2 +1.9 4.1 260 +0.6 +2.1 4.6 270 +0.4 +2.1 3.7 280 +0.6 +2.1 4.6 290 +1.2 +1.9 4.1 300 +2.8 +0.9 1.8 310 +5.4 -4.6 9.1 320 +4.4 -0.2 4.1 330 +3.0 +2.6 0.4 340 +3.7 +4.6 11.9 350 +7.0 +4.3 82.0

PATTERN BANDWIDTH CHARACTERISTICS FROM PHASE/RATIO MEASUREMENT SWEEPS

Pattern Bandwidth Effects

End12:00 PM




Break10:30 AM


RackleyTransmitter Load Optimization for HD Radio9:30 AMX



8:40 AMX


8:20 AMX




24

Transmitter Load Optimizationfor HD Radio


and HD Radio

Optimizing Load Impedance

• Reduces Noise from Digital-To-Analog Crosstalk• Improves Spectral Purity of Digital Signal • Improves Headroom for Receiver Error

Correction

Final Amplifier Load Optimization

FINALAMPLIFIER

OUTPUTMATCHING AND

FILTERINGNETWORK

LOAD MUST BESYMMETRICAL HERE

TRANSMITTEROUTPUT PORT

+J 1.0

-J 1.0

J=0.0

R=1.0

0 DEGOR

180 DEG

45 DEG

90 DEG

135 DEG

TOWARD GENERATOR

SMITH CHART BASICS

25

Normalizing Per-UnitValues of Impedance

• Divide Each Sideband Resistance by the Carrier Resistance

• Divide the Difference Between Each Sideband Reactance and the Carrier Reactance by the Carrier Resistance

Normalizing Examples

+j 0.121.09+j 10.057.0+15 KHz

j 0.001.00-j 3.552.5Carrier

-j 0.090.86-j 8.045.0-15 KHz

+j 0.201.14+j 10.057.0+15 KHz

j 0.001.00j 0.050.0Carrier

-j 0.160.90-j 8.045.0-15 KHz

Per-UnitReactance

Per-UnitResistance

ReactanceResistanceFrequency


F(C)

F(L)

F(H)

FINAL AMPLIFIERLOAD IMPEDANCE ASSYMMETRY

F(C)

F(L) F(H)

R

+X

-X

26

Phase Rotation Network

TRANSMITTER

- 45 DEGREEPHASE

SHIFTINGNETWORK


TOANTENNA


F(C)

F(L)

F(H)

UNCORRECTABLE IMPEDANCE ASYMMETRY

F(C)

F(L)

F(H)

R

+X

-X

Transmitters With Transformer Combiners

FINALAMPLIFIERMODULE

OUTPUTMATCHING AND

FILTERINGNETWORK

LOAD MUST BESYMMETRICAL HERE


COMBINER




27

LH

SYMMETRICAL SIDEBAND LOADFOR TRANSMITTER WITH

-135 DEGREE OUTPUT NETWORK

(MOST HARRIS MODELS)

L

H



(MOST BE MODELS)

L

H



(NAUTEL MODELS?)

Case Study

ND Antenna Simple Load OptimizationHarris 50 KW Transmitter

(Mid-Low Band)

28

LOAD AT FINAL AMPLIFIER OF TRANSMITTER FEEDING ND ANTENNA

Frequency

(KHz)

Before

VSWR

After

VSWR

Recommended Maximum

VSWR -15 1.88 1.45 1.40 -10 1.51 1.25 1.20 -5 1.20 1.10 --

Carrier 1.00 1.00 1.00 +5 1.18 1.10 -- +10 1.34 1.25 1.20 +15 1.47 1.42 1.40

LOAD AT OUTPUT OF TRANSMITTER FEEDING ND ANTENNA

Frequency

(KHz)

Before

VSWR

After

VSWR

Recommended Maximum

VSWR -15 1.25 1.28 1.40 -10 1.18 1.17 1.20 -5 1.09 1.09 --

Carrier 1.00 1.00 1.00 +5 1.09 1.09 -- +10 1.18 1.19 1.20 +15 1.29 1.29 1.40

LOAD AT FINAL AMPLIFIER OF TRANSMITTER FEEDING TEST LOAD

Frequency

(KHz)

Before

VSWR

After

VSWR

Recommended Maximum

VSWR -15 1.51 -- 1.40 -10 1.32 -- 1.20 -5 1.15 -- --

Carrier 1.00 -- 1.00 +5 1.16 -- --

+10 1.33 -- 1.20 +15 1.53 -- 1.40

Case Study

ND Diplexed AntennaFilter Redesign and Load Optimization

BE 5 KW Transmitter(Low Band)

29

LOAD AT OUTPUT OF TRANSMITTER FEEDING DIPLEXED ND ANTENNA

Frequency (KHz)

Before

VSWR

After

VSWR

Recommended Maximum

VSWR -15 1.20 1.36 1.40 -10 1.16 1.20 1.20 -5 1.09 1.09 --

Carrier 1.00 1.00 1.00 +5 1.13 1.07 --

+10 1.32 1.19 1.20 +15 1.57 1.38 1.40

Case Study

DA Antenna Phasor Redesign and Load Optimization

Harris 5 KW Transmitter(Low Band)

LOAD AT OUTPUT OF TRANSMITTER FEEDING DAYTIME COMMON POINT

Frequency

(KHz)

Before

VSWR

After

VSWR

Recommended Maximum

VSWR -15 N/A 1.29 1.40 -10 2.51 1.17 1.20 -5 1.44 1.08 --

Carrier 1.00 1.00 1.00 +5 1.24 1.07 --

+10 1.50 1.16 1.20 +15 N/A 1.27 1.40

Case Study

DA Antenna Phasor Redesign and Load Optimization

Harris 5 KW Transmitter(Low Band)

30

LOAD AT OUTPUT OF TRANSMITTER FEEDING NIGHTTIME COMMON POINT

Frequency

(KHz)

Before

VSWR

After

VSWR

Recommended Maximum

VSWR -15 N/A 1.30 1.40 -10 4.57 1.17 1.20 -5 2.21 1.07 --

Carrier 1.00 1.00 1.00 +5 2.59 1.05 --

+10 5.86 1.12 1.20 +15 N/A 1.24 1.40

Case Study

DA Antenna Load Optimization Not Possible

Due to Assymmetry(Low Band)

LOAD AT OUTPUT OF TRANSMITTER FEEDING DIRECTIONAL ANTENNA

Frequency (KHz)

Before

VSWR

After

VSWR

Recommended Maximum

VSWR -15 2.07 -- 1.40 -10 1.78 -- 1.20 -5 1.41 -- --

Carrier 1.00 -- 1.00 +5 1.63 -- -- +10 2.22 -- 1.20 +15 4.35 -- 1.40

Impedance Effects on Signal Sampling

• Sideband Impedance Characteristics at Sampling Point Influence Spectrum Measurements

• Observations Within Transmission System May Not Represent Far-Field Signal

31


F(C)

F(L)

F(H)

F(C)F(C) - F(M) F(C) + F(M)


LH



(MOST HARRIS MODELS)

F(C)F(C) - F(M) F(C) + F(M)


32

F(C)F(C) - F(M) F(C) + F(M)


F(C)F(C) - F(M) F(C) + F(M)


33

For Printable Versionand Network Analyzer System Details

E-Mail [email protected]

Subject: NAB Presentation

End12:00 PM




Break10:30 AM

Cox/WarnerWhere the Bandwidth Meets the Load10:00 AMX

RackleyTransmitter Load Optimization9:30 AMX



8:40 AMX


8:20 AMX




Where the BandwidthMeets the Load

John Warner Tom Cox, PE

34

• Impedance Sweep Plots

• Harris DX10• -225° Output

Network

Rotation Correction Network

Station set up using sample toroid at output of transmitter

Far field measurement of the same station

35

The pictures look different depending on where I look…

• Far field– 4 cardinal points at approximately 1 km

• Power bus using an inductive coupling loop• Transmitter output

– Modulation monitor output port (voltage sample)– Sample toroid (current sample)

• Output of rotation correction network– Sample toroid

• Unused sample loop

Test Station

• 50 kW ND day• 50 kW 3 tower DA night• Harris DX50 transmitter• Harris Dexstar AM IBOC Exciter

Far Field Measurement West• 1 km 273° T• Chris Scott

LP-3 Standard H-field antenna

• AgilentE4402 SA

Far Field Measurement North• 1.03 km 10°• Chris Scott

LP-3 Standard H-field Antenna

• AgilentE4402 SA

36

Far Field Measurement East• 1.26 km 98° T• Chris Scott LP-

3 Standard H-field Antenna

• Agilent E4402 SA

Far Field Measurement South• 1.03 km 166°• Chris Scott

LP-3 Standard H-field Antenna

• AgilentE4402 SA

Power Buss using inductive loop

• 2 turn loop• Approximately 20

V p-p

Power Buss using inductive loop

• 2 turn 4” loop terminated with 50 ohms placed 6” from strap connecting power bus to input of transmitter output network

37

Transmitter Output• Modulation

monitor port (voltage sample)

Transmitter Output• Sample

toroid(current sample)

Output of rotation correction network (-85°)

• Sample toroid(current sample)

Unused Tower Sample Loop

• East tower loop

38

WHJJ As Found After Adjustment, Transmitter Output

Field Measurement WCAO Transmitter Sample

39

Common Point Toroid Tower 1

Tower 2 Tower 3

40

Tower 4 Far Field

1 Meter Loop “Portable” Loop

41

Remote Exciter Access

End12:00 PM




Break10:30 AMX





8:40 AMX


8:20 AMX




42

BREAK TIME!


and HD Radio End12:00 PM



Transmitter Characteristics Panel11:00 AMX

Break10:30 AMX





8:40 AMX


8:20 AMX




Transmitter Characteristics Panel


and HD Radio

Load Impedance Considerations for Nautel AM IBOC TransmittersSeptember, 2005

© Nautel Limited 2005This presentation has been produced for Nautel customers and agents and is not for distribution without the expressed written consent of Nautel.

43

Overview

• RF Harmonic Filter Topologies (Bandpass & Lowpass)

• Goals at Nautel

• What to do with your current or future Nautel transmitter

Low Power Transmitter – Bandpass

-

+-J100+J100

-J25

+J100 -J10050

S2010094-A V1

+J25

•Full Bridge Class-D amplifier: Voltage Source•Low Power Transmitters, J1000 and ND1•Theoretical Phase Delay is Zero•Capacitor Tolerance is not a problem

Low Pass Topology

n

1

2

-

-

+

-50

+

+

S2010094-B V1

•High power transmitters: XR Series, XL Series and ND5-50•Ideal phase is 195 – 210 degrees depending on model and frequency•High phase Sensitivity of T section to capacitance changes

Phase Sensitivity of T Section

Example of 25 to 50 ohm T section

44

Current Focus at Nautel

• Make zero delay standard on J1000• Investigate the possibility of making 180 degree phase delay

standard on XR series. (May not be attainable without some tolerance or extra cost.)

• Beginning an experimental investigation to provide a factory recommendation for antenna impedance requirements at the transmitter output terminals

• Experimental Setup employs a series tuned resonant circuit with 1.4:1 VSWR at plus/minus 15 kHz

• T section allows rotation of impedance cusp

Series Resonant Condition Series Resonant with 30° Phase Delay

45

Series Resonant with 60° Phase Delay Parallel Resonant

What can you do?

• If you have an existing transmitter and there is no phase information from the factory, a measurement is required to determine RF filter phase

• Measurement can be made using a two channel oscilloscope, although high voltage probes may be required

• Current shipments are provided with delay measurement and equivalent circuit (XR Series)

• Future shipments can be shipped with a specific delay – consult your sales representative at time of purchase

Questions?

Thank You!

[email protected]

46

Antenna Loads for AM TXs and HD RadioTM

The NAB Radio Show September 22nd, 2004

AM-1A, AM 500

AM-10A, AM-6A, AM-5E, AM-2.5E 4MX 50

47

AM-1A 1.5:1 @ 15kHz

AM-1A Load Impedance Plot 1.5:1 @ 15kHz

Effects of Antenna Load on Spectrum

Modified AM into 50ohms Modified AM into 1.5:1 VSWR@ 10kHz

-20kHz 2nd Adj +20kHz 2nd Adj

Effects of Antenna Load on Spectrum

-20kHz 2nd Adj +20kHz 2nd Adj

4MX 50 Network Sweep

48

ANY QUESTIONS?

[email protected]

(217) 224-9600

HD Radio Antenna Seminar - Geoff Mendenhall assured communicationsSeptember 22, 2005

AM Directional Antennas in a Digital World

NAB Radio Show 2005

Presented By:

Geoff Mendenhall

VP – Research and Development


Phase Rotation of Load

• The load presented to the RF Power Amplifier FET’sneeds to provide symmetrical loading for both sidebands so that the power output is equal for upper and lower sidebands

• There are two points on the Smith chart that provide this symmetry, but the preferred point is where the resistive component of the load presented to the FET’s is lower at the sideband frequencies. This causes the amplifier to output more power at the sidebands which tends to compensate for the roll off in frequency response of the antenna system at the sideband frequencies

• Symmetrical loading of the RF amplifier is key to maintaining RF mask compliance


Locations of Phase Rotations

0 Degrees

3:00 o’clock

-45 Degrees

6:00 o’clock

“horns down”

-90 Degrees

9:00 o’clock

-135 Degrees

12:00 o’clock

“horns up”

49


Phase Shift in Transmitter Output Network

CH1 S 11 1 U FS

START 1.065 000 MHz STOP 1.095 000 MHz

Cor

PRm

MARKER 1 1.08 MHz

8 Sep 2005 11:10:53

1

1_: 8.2681 2.5874 381.29 nH

1.080 000 MHz

CH1 S 11 1 U FS


Cor

PRm

MARKER 1 1.08 MHz

8 Sep 2005 11:19:29

1

1_: 50.314 -1.0781 136.69 nF

1.080 000 MHz

Impedance at Amplifier FET’s Impedance at Transmitter Output


Harris Transmitters into iBiquity Load

• Harris is testing DAX and 3DX transmitters into iBiquity’s maximum recommended VSWR load circle

• Artificial antenna consists of series tuned LC network with a Q (11.6@1080KHz) sufficient to create 1.4:1 VSWR at +/- 15KHz from carrier

• HD Radio reception can be maintained at higher VSWR’s than what is required to maintain RF Mask compliance

• RF Mask compliance requires 3rd order spectral re-growth to be at least 65dB below un-modulated AM host carrier level


Artificial Antenna Circuit


DAX-6 into iBiquity Artificial Antenna

50


Location of Spectrum Sample Point

• The position of the sample point can affect amplitude flatness (tilt) across the sidebands and introduce distortion to the RF envelope shape, but it can not introduce new spectral components as long as the transmitter is not overmodulated

• The spectrum should be flat (equal upper and lower digital sideband levels) across the channel at the RF load

• In the case of directional array, the question is: Where should equal amplitude of the upper and lower sidebands occur in the far field ?


DAX-6 into iBiquity Artificial Antenna


Tips for AM HD Radio Installations

• Envelope modulation of transmitter and DexStar must be closely matched so that phase modulated carrier output from HD-Radio exciter is not interrupted by “pinch off” of internal EER extractor

• Use missing pulse protection board on 3DX-50• Use phase shift network to rotate complex

impedance plot to “11:00 o’clock, horns up” position on smith chart

• Keep antenna VSWR less than 1.4:1 @ +/- 15KHz

CH1 S 11 1 U FS


Cor

PRm

MARKER 1 1.08 MHz

8 Sep 2005 11:19:29

1

1_: 50.314 -1.0781 136.69 nF

1.080 000 MHz


Summary of Findings

• The Harris DAX transmitters have best RF mask performance into a symmetrical load that is rotated 125 degrees +/- 10 degrees clockwise (11:00 o’clock position) and presented to the RF output connector

• The Harris 3DX-50 transmitter has the same output network topology as the DAX and should best performance into to same load angle as the DAX (11:00 o’clock position)

• The Harris DX-10 and DX-50 transmitters perform best into a symmetrical load that is rotated 135 degrees +/- 10 degrees clockwise (12:00 o’clock position) and presented to the RF output connector

• Harris can provide "equivalent circuit" models that can be integrated into computer models of antenna systems

51


Questions ?

End12:00 PM

All Questions and Answers11:30 PMX



Break10:30 AMX





8:40 AMX


8:20 AMX




Questions?


and HD Radio End12:00 PMX

All Questions and Answers11:30 PMX



Break10:30 AMX





8:40 AMX


8:20 AMX

8:00 AMX



thursday, september 22, 2005 part ii – am antenna …00 am transmitter characteristics panel ... +...

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