Advanced Passive Components for UHF Broadcast Spectrum Reallocation

RADIO FREQUENCY SYSTEMS

Advanced Passive Components

for

UHF Broadcast Spectrum Reallocation

Benedikt Scheid Senior Engineer R&D - Broadcast Division

Radio Frequency Systems

16th October 2015

Special thanks for their contributions to

Yan Cao, Jonathan Chi, Ernest Fardin, Dieter Pelz and Nick Wymant


Overview

• The Australian repack experience & the looming US repack

• Old and New - adjacent channel high power combiner systems

• 1st adjacent channel combiner component: 50 kW fully tunable filter

• 2nd adjacent channel combiner component: High power 3 dB couplers

• Repack scenario: OK, I have a tunable 50 kW filter - who can tune it?


RFS’ recent experience in the

Australian repack:

520 MHz 820 MHz

Before

520 MHz 694 MHz

After


• Project timeframe: Feb. ‘13 - Sep. ’14

• Channels clustered into 5 x 6 adjacent channel blocks

• About 1300 channel changes

• MS project file contained 13,000 tasks with 100,000 dependencies!1)

Australian Frequency Repack Stats

1)Source: Broadcast Australia

1)

RADIO FREQUENCY SYSTEMS The looming US repack

• Project timeframe: Mid ‘16 - End ’19 ?

• Post repack UHF TV Band 470 MHz - ~608 MHz ?

• Tunable and broadband equipment desirable to protect investment

from further changes – ATSC 3.0 ?

• Adjacent channel combining would offer the ability for everybody to

share a common antenna

The looming US repack


• Adjacent channel combining – no problem

• High power handling capability (~250 kW)

• Relatively small footprint

• Fixed channel – not tunable

Traditional high power UHF combiner

technology

2008

RFS 10 CH ‚Superchain‘

Old and New - adjacent channel high power combiner systems


• Combine any channels between CH 14 – CH 41

including adjacent channels

• Maximum individual channel input: 100 kW

• Maximum combined power output: 320 kW

• If channels change, simply re-tune on site!

6 CH tunable adjacent channel combiner

Fully tunable high power UHF combiner

2015

Old and New - adjacent channel high power combiner systems


What was required to achieve this

product innovation?


1st adjacent channel combiner component:

50 kW fully re-tunable UHF filter

RADIO FREQUENCY SYSTEMS 50 kW Fully re-tunable UHF Filter

• 473 MHz – 635 MHz tuning range (Ch14-41)

• <0.2 dB insertion loss (>95.5% efficiency)

• Liquid cooled

• Very compact

(considering its power rating and tunability)

6PPXX325E – 50 kW re-tunable UHF TV filter


• Input power: 50 kW

• Ambient: 77⁰ F

• Coolant temp.:131⁰ F

• Body: 138⁰ F

Thermal simulation

Liquid Cooling Ducts

Ansys thermal simulation using heat flux data from 3D EM simulation (Ansys HFSS)

50 kW Fully re-tunable UHF Filter


Thermal verification – power test

Thermal imager picture of 50 kW filter during power test


• Input power: 50 kW

• Ambient: 77⁰ F

• Coolant temp.:131⁰ F

• Body: 142⁰ F


Low filter temperature – less filter insertion loss


Copper conductivity [%] VS. temperature


Why do we care about low average filter temperature?


TX power 50 50 kW

Filter loss (average over signal bandwidth) @ 68°F (20°C) 0.200 0.200 dB TX efficiency ( Pout_rf / Pin_ac ) 45 45 % Operating Life Time 20 20 Years Cost per kWh 15 15 Cents

Filter operating temperature 68 176 ° F Filter operational insertion loss 0.200 0.239 dB Filter efficiency 95.5 94.7 %

Cost over operating life time 131.5 156.2 k$

25k$ difference - an extra 0.1dB insertion loss would cost ~62k US$...


Less filter insertion loss – higher overall TX efficiency


TX overall efficiency VS. filter insertion loss

( Pout_rf / Pin_ac )


Filter Tuning Range

50 kW filter mask response plot summary

• 473 MHz – 635 MHz (Ch14 – Ch 41)

• Constant S21 response across

tuning range

• Adjustable selectivity to meet TX

requirements



2nd adjacent channel combiner component:

High Power 3 dB Couplers


• Frequency Range: 470 MHz – 700 MHz

• Max. Power:

80 kW with 7-3/16” output transmission line

125 kW with 8-3/16” output transmission line (up to 614 MHz)

• Thermal Management: Remove heat from inner conductors via

a thermal connection1)


Coaxial high power 3 dB coupler

Coaxial 3 dB coupler

1)Patent application filed

RADIO FREQUENCY SYSTEMS High Power 3 dB Couplers

Coaxial coupler used to combine TX cabinets

Coupling Response of high power coaxial 3dB coupler High power 3dB coupler used to combine TX racks

1)

1)Source: Rohde & Schwarz

~0.35dB coupling ripple


• Frequency Range: 470 MHz – 640 MHz

• Max Output Power: 320 kW

• Compact design due to broad side coupling

Why does a waveguide coupler handle more power?

• No inner conductor

• 65% less average current density

Waveguide high power 3 dB coupler

Waveguide 3 dB coupler



High Power Tunable Combiner module • Frequency Range: 470 MHz - 640 MHz

• Max. Input Power per Channel:

100 kW

• Max. Combined Output Power:

320 kW

• Adjacent channel combining across the UHF band

• Smart interface to waveguide coupler1) 100 kW tunable combiner module

1)Patent application filed


6-Channel Combiner Example

Footprint (LxWxH)

19 ft x 5.2 ft x 10.8 ft

(5.8 m x 1.6 m x 3.3 m)

Combiner

Output

CH 6 CH 5

CH 4 CH 3

CH 2 CH 1

Typical group delay about <350 nS

RADIO FREQUENCY SYSTEMS Broadcast Computer Aided Tuning

Repack scenario:

OK, I have a tunable 50 kW filter – who can

re-tune it? With Broadcast Computer Aided

Tuning (BCAT), (almost) anyone


Broadcast Computer Aided Tuning

(BCAT)


• Tuning software specific to broadcast

• Factory Tuning anytime/anywhere

• Stress-free re-tuning without trial/error

• Very fast algorithm for real time feel

• Only limited experience needed

BCAT general user interface

BCAT


S-parameters

BCAT

Tuning Actions

The BCAT tuning cycle

Visualization of

tuning errors


Filter tuning demonstration using BCAT

BCAT tuning video

Video by: Upul Bulathsinhala and Serge Piastra

Conclusions

• A new class of products have been developed providing both high power and

frequency agility

• Computer Aided Tuning provides the ability to retune a mask filter on the spot

• Adjacent channel combiners enhance site flexibility and efficiency by removing the

need for multiple antennas.

• For good overall transmitting efficiency filter losses and operating temperatures should

be considered

• The repack in Australia has shown that with careful planning, a repack can be

successfully accomplished in a short period of time

www.rfsworld.com

• • • •

• • • • •

• • • • • • • • •

• • • • • • • • • • •

Dubai

Johannesburg

Kolkata

Madrid

Monza

New Delhi

Paris

Pacy

Trignac/Lannion

Coconut Creek

Mansfield

Meriden

Naperville

San Jose

Bangkok

Beijing

Guangzhou

Hong Kong

Jakarta

Kuala Lumpur

Melbourne

Shanghai

Singapore

Taipei

Tokyo

EUROPE

NORTH

LATIN

AMERICA

NORTH

AMERICA

ASIA

PACIFIC

SOUTH EUROPE, MIDDLE

EAST, AFRICA & INDIA

Thank You for your attention!

Bogota

Buenos Aires

Mexico City

São Paulo

Copenhagen

Haddenham

Hannover

Moscow

Warwick

• • • • •

© Radio Frequency Systems

2015. All rights reserved


Backup Slides


How does a balanced combiner work?


Presentations & Public Speaking

Advanced Passive Components for UHF Broadcast Spectrum Reallocation