Getting Ready for the Repack – • Antennas • Transmission Line • RF Systems Re-use or Replace ? Daniel S Fallon Sr. RF Engineer
Repack / Transition Timeline
Overview • Towers • Antenna’s • Transmission Line • RF Systems • Transition Scenario's
Towers • TIA-222 Rev G
Towers • TIA-222 Rev G Ice Wind Speed Topography Get structural analysis Need detailed site information
Antennas • Pylon • Less ERP required • Narrowband at lower channels • Moving down in channel = to replicate larger antenna coverage Antenna not • Some may allow adjacent • necessarily longer channel operation Replace
Antennas • Panel • Joining a Panel Broadband • • All stations have common • Owned by “vertical real- pattern estate” companies • Number of channels can be • Broadcaster going dark may limited by Power open up space on panel Re-use • FCC is not considering moving Tx location during “re-pack” phase of the auction • Application to move to a new Tx site will be done post auction
Multi-Channel Pylon Example of a broadband slotted coaxial antenna design WNYT Glens Falls, NY TLP-12W/VP-R (SP) channels 39 & 45 • 12 layer antenna with 4 way split Multi-sectional phase cancellation • Manufactured in ½” wall aluminum Lower Q from thin wall Elliptically polarized • Leveraging Babinet’s principle Channels 38 to 47 under 1.1:1
Coaxial line “stick” length, 3 MHz Guard Band 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 20 19 ¾ 19 ½ 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 20 19 ¾ 19 ½ Prohibited Channel per catalog
Coaxial line “stick” length, 1.5 MHz Guard Band 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 20 19 ¾ 19 ½ 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 20 19 ¾ 19 ½
Transmission line • Get a line sweep • 6 1/8” line 20’ stick length • Ch 16 and 20 are OK (<1.03:1) Channels 14 to 24 Sweep curtesy Ed Murlatt and associates Maybe Re-use
RF Systems • High Power RF System Components (25kW-80 kW) WR1150 Ch44-69 WR1500 Ch18-48 WR1800 Ch14-17
RF Systems • High Power RF System Components Coax to Waveguide Transitions Narrowband Replace
RF Systems • High Power RF System Components Waveguide Magic Tee Combiner New Slabs Required Re-tune
RF Systems • High Power RF System Components Waffle Iron Low Pass Filter Re-tune
RF Systems • High Power RF System Components Constant Impedance Band-pass Filter Replace
RF Systems • High Power RF System Components Waveguide Switch and Coaxial Water-load Re-tune
RF Systems • Medium Power RF System Components (10kW-25 kW) Replace filter All components are Re-use all else broadband except waveguide filter
RF Systems – Practical Considerations • Field re-tuning not practical – Limited qualified talent – Some parts may need to be replace • If have two tube system – Re-tune one tube and operate into new CIF – Send all other system parts for refurbishment
Transition Scenario’s FLASH CUT FLASH CUT FLASH CUT FLASH CUT STAGED • On air with original channel today On air with new channel tomorrow • GOT BACKUP? GOT BACKUP? GOT BACKUP? GOT BACKUP? NEED TEMPORARY TRASMISSION FACILITY
Transition Scenario’s - Staged
If you have backup • Operate off backup site while work is done at main site to get ready for new channel • Expect several months of back-up operation • Reliable back-up is important
Analog antenna still up? • Operate off current digital channel • Replace analog antenna (top mount)
Currently no Aux Antenna ? • New side mount on new channel • Replace top mount post cut over • Side mount becomes backup If re-using Tx line tower a top channel splitter • can be used to feed side mount • Side mount can go at separate site and be used as part of SFN or as backup post transition • Put up side mount on current channel
Candelabra ? • Candelabra – New full power antenna • New Stacked antenna with another broadcaster • Space made available by broadcaster going off air ?
Dual Channel Slot? • Several dual channel slots went up during DTV conversion • These are currently operating on one channel only Antenna, line and combiner are ready • for broadcaster in market repacked to that adjacent channel • Operation from same aperture on adjacent channel will mitigate interference • Apply to FCC to change broadcast site
Panel? • Join existing or new panel as tenant • Space made available by broadcaster going off air ? • Will require combiner work New manifold combiner • • Possible broadband port addition or module replacement in CIF • Vertical real estate company owns and upgrade hardware, broadcasters lease
New Multi-Channel Pylon 9 % = ch14-21 (5 channels) ch30-38 (8 channels) ch34-42 (8 channels) ch42-51 (9 channels) Channels 38 to 47 under 1.1:1
ATSC 3.0 • Add V-Pol to help mobile reception • Single Frequency Network (SFN) topology
Conclusions • A temporary or back up transmission facility will be required • Antennas will most likely have to be replaced • Good chance that transmission line can be re-used Some RF system components can be re-used • • Don’t plan on field re-tuning • Least expensive option would be to move to existing transmission site if it is available in the market
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