HORIZONTALLY POLARIZED OMNI COMPARISONS (490 MHz) [Ordered by Gmin in each Category.]

Transcription

1 HORIZONTALLY POLARIZED OMNI COMPARISONS (490 MHz) [Ordered by Gmin in each Category.] 13-Apr-16 holl_ands A. TRUE OMNI: [Roughly EQUAL GAIN in ALL Directions, preferably less than +/- 1 db] Gmin Gmax SWR SWR Char. Elev. Null (dbi) (dbi) Min Max Imped. Depth A1 7-El Yagi (w. Refl) TRIAD Array dbi El=-48-deg dbi El=-58-deg A2 6-El Yagi (w. Refl) TRIAD Array dbi El=-36-deg dbi El=-50-deg dbi El=-54-deg dbi El=-56-deg A3 4-El Yagi (w. Refl) TRIAD Array Not a Problem A4 5-El Yagi (w. Refl) TRIAD Array Not a Problem A5 3-El Yagi (No Refl) TRIAD Array Not a Problem A6 4-El Yagi (No Refl) TRIAD Array Not a Problem A7 2-El Yagi (No Refl) TRIAD Array Not a Problem A8 5-El Yagi (w. Refl) QUAD Array dbi El=-48-deg SWRTooHigh dbi El=-58-deg A9 6-El Yagi (w. Refl) QUAD Array dbi El=-48-deg SWRTooHigh dbi El=-58-deg A10 3-El Yagi (No Refl) TRIAD Array dbi El=-44-deg A11 4-El Yagi (w. Refl) QUAD Array dbi El=-24-deg dbi El=-38-deg A12 2-El Yagi (w. Refl) TRIAD Array ### dbi El=-44-deg SWRTooHigh A13 7-El Yagi (w. Refl) QUAD Array dbi El=-44-deg dbi El=-56-deg A14 Triangle 3X Dipole TRIAD Array Not a Problem 200-ohm bit better than 50-ohms Not a Problem A15 Square 4X Dipole QUAD Array Not a Problem

2 [Why better OMNI Pattern at 470 MHz???] SWR TooHigh

3 A. TRUE OMNI: [Continued] A16 4-El Yagi (No Refl) QUAD Array Not a Problem [WHY WORSE????] [And Reversed Phase Elements on Opposite Antennas are MUCH WORSE.] A17 HALO Single Loop Gap = 5.00-in Not a Problem Omni: Gap = T.B.D. ~0.9 ~1.5 TBD TBD TBD Not a Problem Quasi: Gap = 1.89-in Not a Problem Quasi: Gap = 0.63-in High High 2226 Not a Problem Need to Adjust Gap for Low SWR w. 50 or 200-ohm Load - But VERY CRITICAL Dimensions B. OMNI-PLUS: [Gain Greater Than Gmin in ALL Directions and PLUS that in SOME Directions] Gmin Gmax SWR SWR Char. Elev. Null (dbi) (dbi) Min Max Imped. Depth B1 Flat-Swept SBGH dbi El=-38-deg B2 Swept FF dbi El=-40-deg SWRTooHigh -15 dbi El=-18-deg B3 Double ZZ8 (Similar to Swept SBGH) dbi El=-18-deg -24 dbi El=-32-deg -22 dbi El=-62-deg B4 Hourglass-Loop TRIAD Array + FL's Down Angle = 0-deg El = dbi El=-42-deg B5 QuadTrap-Loop+2Bars TRIAD Array + FL's SWR TooHigh Down Angle = 0-deg El = dbi El=-28-deg Down Angle = 2.5-deg El = dbi El=-30-deg Down Angle = 5-deg El = dbi El=-36-deg Down Angle = 7.5-deg El = dbi El=-42-deg [Down Angle = 5-deg is "Enough" to suppress Elev. Null.] C. QUASI-OMNI: [Gain Less than 0 dbd = 2.15 dbi in SOME or MANY Directions] C1 C2 Double Diamond Quad + 90-deg TL's 486 MHz MHz dbi El=-32-deg 494 MHz Hourglass-Loop QUAD Array + FL's Down Angle = 2-deg El = Not a Problem Down Angle = 2-deg El = Not a Problem

4 [WHY OMNI GAIN LOSS & HIGH SWR??] SWR TooHigh C3 Double Hoop [FM Band Data] ~1.2 ~2 50 Not a Problem [ReRun 490 MHz w. Variable Gap for Best SWR] SWR TooHigh C4 Swept FF T.B.D. SWR TooHigh

5 DVB-T Ch23 RANGE CALCULATOR Enter data ONLY into BLUE fields holl_ands 14-Apr-16 FSPL = 20*log(km) + 10*log(freq) db [Free Space Path Loss] Normalized RX Power (dbm) = EIRP (dbm) - FSPL (db) "WORST" is for Antenna pointed in some OTHER direction and hence about 0 dbi Gain toward 490 MHz. Required PAL SNR = 25+ db Grade2 (Very Annoying), 30+ db Grade3 (Annoying) and??? db Grade 4 (Noticeable) and min. 43 db for IEC Required DVB-T C/N (For 3/4 Code in 8 MHz) = 18.6 db (64QAM at 24.9 Mpbs), 13.0 db (16QAM at 16.6 Mbps) and 6.8 db (QPSK at 8.3 Mbps) For Ricean Channels, From 3 DIPOLES IN TRIAD ARRAY: BEST TYPICAL WORST Xmtr Power (watts) = watts Xmtr Power (dbm) = dbm TX Cable Losses = db (Need to Minimize Length of LOW LOSS Cable) TX Balun Loss = db (Recommend Low Loss Coax 4:1 Balun) TX Antenna Gain (Min) = db [MIN. FOR 3 DIPOLES IN TRIAD ARRAY] EIRP (dbm) = dbm EIRP (watts) = watts Max Range = km Free Space Path Loss (db) = db (For 1 km at 490 MHz) Normalized RX Power (dbm) = dbm (For 0 dbi RX Antenna, No RX Losses) RX Antenna Gain = dbi (0 dbi "Typical" when NOT pointed to Station) Balun + Cable Losses = dbi RF Splitter Losses = dbi RX Power at Tuner Input = dbm (Preamp will improve on these numbers) Tuner NF = db 7.6 MHz Noise Power at Tuner Input = dbm CNR is about equal to SNR = db [= Rx Power - NF ] Analog PAL"Suitability" = POOR NO NO DVB-T "Suitability" = GOOD FAIR POOR "Typical" DVB-T Rate Supported = 64-QAM 16-QAM QPSK "Typical" DVB-T CNR Required = SNR Margin =

6 FLAT-SWEPT SBGH: BEST TYPICAL WORST Xmtr Power (watts) = watts Xmtr Power (dbm) = dbm TX Cable Losses = db (Need to Minimize Length of LOW LOSS Cable) TX Balun Loss = db (Recommend Low Loss Coax 4:1 Balun) TX Antenna Gain (Min) = db [MIN. FOR FLAT-SWEPT SBGH] EIRP (dbm) = dbm EIRP (watts) = watts Max Range = km Free Space Path Loss (db) = db (For 490 MHz) Normalized RX Power (dbm) = dbm (For 0 dbi RX Antenna, No RX Losses) RX Antenna Gain = dbi (0 dbi "Typical" when NOT pointed to Station) Balun + Cable Losses = dbi RF Splitter Losses = dbi RX Power at Tuner Input = dbm (Preamp will improve on these numbers) Tuner NF = db 7.6 MHz Noise Power at Tuner Input = dbm CNR is about equal to SNR = db [= Rx Power - NF ] Analog PAL"Suitability" = GOOD POOR NO DVB-T "Suitability" = GOOD GOOD POOR "Typical" DVB-T Rate Supported = 64-QAM 64-QAM QPSK [Probably WORSE at some Locations] "Typical" DVB-T CNR Required = SNR Margin =

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8 ANTENNA LOOK DOWN ANGLE vs RANGE Angle = (180/ )*ASIN(DeltaHt/1000*Range) 15-Feb-16 holl_ands TX Height Advantage (m)= RANGE (km) = #VALUE! #VALUE! #VALUE! #VALUE! #VALUE! #VALUE! LOOK-DOWN ANGLE: LOOK-DOWN LOSS (db): LOOK-DOWN LOSS + 20 db (PROPAGATION GAIN FOR 0.1 km vs 1.0 km):

9 #VALUE! #VALUE! #VALUE!

10 3-Dipole Triangle - Look Down Angle vs Tower Height Advantage (meters) Advantage = 10-m Advantage = 20-m Advantage = 30-m Advantage = 40-m Advantage = 60-m Advantage = 80-m Look Down Angle (degrees) Loss = 10 db Loss = 6 db Loss = 3 db Loss = 2 db Loss = 1 db Loss = 0.5 db Range (km)

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12 Flat-Swept SBGH OMNI - Look Down Angle vs Tower Height Advantage (m) Advantage = 10-m Advantage = 20-m Advantage = 30-m Advantage = 40-m Advantage = 60-m Advantage = 80-m Loss = 20 db Look Down Angle (degrees) Loss = 3 db Loss = 1 db Loss = 12 db Loss = 30 db Loss = 20 db Loss = 16 db Loss = 20 db Loss = 10 db Loss = 6 db Range 0.25 (km)

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