Presentation on theme: "The Mystery Band by Marc C. Tarplee, Ph.D. N4UFP"— Presentation transcript:
1 The Mystery Band by Marc C. Tarplee, Ph.D. N4UFP 6 MetersThe Mystery Bandby Marc C. Tarplee, Ph.D.N4UFP
2 6 Meters: Rhetoric vs. Reality No one is on 6 meters(I’ve made over 1900 QSO’s on 6 m since 1992)There is no DX on 6 meters(I’ve worked 46 states and 38 countries on 3 continents)6 meters is the TVI band(I have never had a TVI complaint from my neighbors)
3 What makes 6 m interesting? A wide variety of operating modes is availableNo band offers a wider range of propagation phenomena than 6 mStation equipment requirements are modestAntenna experimentation is much easier on 6 m than the HF bands
4 6 Meter Band PlanCW, beacons (beacon sub band = MHz)SSB, CW (SSB calling frequency = MHz)DX windowAll modesNonvoice communications (digital calling frequency = MHz)Radio remote control (20-kHz channels)Pacific DX windowRepeater inputs (19 channels, digital repeater inputs are MHz)Repeater outputs (19 channels, digital repeater outputs are MHz)Repeater inputs (except as noted; 23 channels)52.02, FM simplexTEST PAIR (input)Repeater output (except as noted; 23 channels)Primary FM simplexSecondary FM simplexTEST PAIR (output)Repeater inputs (except as noted; 19 channels)Remote base FM simplexSimplex53.1, 53.2, 53.3, Radio remote controlRepeater outputs (except as noted; 19 channels)53.5, 53.6, 53.7, Radio remote control53.52, Simplex
5 6 Meter Propagation Every type of propagation is possible on 6 m: Line of SightTropospheric PropagationSporadic EMeteor ScatterAuroral ScatteringTransequatorial FIonospheric F2
6 Line of Sight (LOS) and Tropospheric Propagation LOS coverage is determined primarily by the height of the transmitting and receiving antennasFor typical amateur 6 m stations LOS coverage is about 20 milesLOS propagation is unaffected by solar conditions, time of day or the seasonsTropospheric PropagationVariations in the humidity of the troposphere cause RF to be scattered over the horizon. This is known as tropospheric scatterTemperature inversions (warm dry air located above cool moist air) refract RF in the VHF range back towards the earth. Temperature inversions occur daily in the middle latitudes at sunrise and sunset. Communications are possible over a ranges up to 600 milesOver the oceans, stable temperature inversions can create a duct, through which VHF can travel without significant loss up to 2500 miles
8 Sporadic E (ES)Clouds of high density ionization form without warning in the ionosphere’s E layerES is not dependent on solar activity. It may occur any time, but is most frequent between May and August, with a smaller peak of activity in DecemberSingle hop ES has a range of ~1400 miDouble hop ES has a range of ~ 2500 miCause of Sporadic E is not known: high altitude wind shear may be responsible.
9 Sporadic E (ES)The ionized clouds that cause sporadic E propagation can move. This animated sequence shows grid squares contacted in ½ hour intervals during an ES opening beginning at 0500 Z, 10 June 2001
10 Meteor ScatterAs meteors are vaporized in the upper atmosphere, they leave behind ionized trails at heights of 60 – 70 miles that are sufficiently dense to reflect VHFA long trail lasts only 15 seconds so contact must be made quickly on SSBSSB QSO’s via meteor scatter are usually possible only during a meteor stormShort trails that occur continuously may be used for high speed CW QSO’s (> 100 wpm)Best time for meteor scatter is after midnight or during a meteor storm
11 Aurora (Au)During periods of intense auroral activity, charged particles in the auroral zone can scatter 50 MHz RFThe RF interacts strongly with the aurora, resulting in significant distortion of the signal. Only narrow band modes such as CW are used during Au openingsTo work Au, the transmitter and receiver point their antennas at the auroral zone, not each other.
12 Transequatorial F (TE) The ionosphere’s F layer is most intense in the region of the geomagnetic equator.Stations within about 2500 miles of the geomagnetic equator can launch 50 MHz RF into these regions. The RF is refracted and travels across the equator and into the other hemisphere without scattering from the groundStations using TE must be at approximately equal distances from the geomagnetic equator
13 F2 propagationCommunications over long distances (> 2000 miles) are possible on 6 m via the F2 layer of the ionosphere during periods of high solar activity (solar flux above 220)Openings generally occur in spring and fall during daylight hours (similar to 10 m)
14 Propagation Example2001 June VHF QSO Party 6 m QSO’s
15 Traditional 6m Operating Modes CWUsed primarily below MHzUsed during auroral openings – narrowband modes like CW are less susceptible to distortionHSCWCW sent at high speeds (200 wpm or more)Used with meteor scatter propagationMost operation takes place near MHzSSBMost common 6m mode - USB is the standardCalling frequency is MHz– MHz is the DX window
16 Digital 6m Operating Modes FSK441Uses triplets of 4 tones to transmit data882, 1323, 1764, 2205 HzEach character is sent as a 3 tone sequence43 Character alphabet (letters, numbers . , / ? # $ <sp>)Single tone characters used for shorthand messages:882 Hz - R Hz - RRR1323 Hz – R Hz - 73Data rate = 147 characters per second (3 tones/char)Used for meteor scatter communicationsMost activity takes place near MHzMessages sent in 30 sec intervals – westernmost station transmits during first 30 seconds of each minute.
17 Digital 6m Operating Modes JT65BNarrowband PSK64-ary PSK (6 bits per baud)~2.7 Baud signaling speed~5.4 Hz operating bandwidthRequires a stable receiver, good timingMessages sent in 60 sec intervals – westernmost station transmits during even-numbered minutes.Provides clear copy at SNR < 0 dBUsed for moonbounce and troposcatter operationMost activity takes place near MHz
18 6 Meter Station Requirements Transceiver or TransverterRF output of at least 10 W PEP (>100W for FSK441, JT65, ~1000W for EME) with multi-mode capability (CW/SSB/FM)ICOM 706, 746, 756Yaesu FT-100, 817, 847, 920Kenwood TS-570Alinco DX-70THAntennaGain of at least 5 dBd (> 15dBd for EME)Should be rotatable (az-el rotation is very important for EME)Should be at least 20 ft above groundUse low loss coax (RG8 up to 75 ft, Belden 9913 for longer runs)Useful accessoriesRF pre-amp (RF switched)Grid Square MapPC (for FSK441, JT65)
19 6 Meter Antennas6 m antennas are relatively small, light and easily rotatable.Best choices for a new operator:2 element quad3 element YagiExtended Double Zepp6/10 dual band dipoleFor weak signal work (CW/SSB) the antenna should be horizontally polarizedFor repeater operation, vertical polarization is the normFor EME an array of 4 long yagis is typicalMeteor scatter operation requires an antenna with good gain and broad beamwidth – 5 to 9 element yagis work well.
20 6 Meter Quad and Yagi Antennas 2 element Quad (square loops of #14 ins. wire Z ~ 60 ohms Gain ~ 4 dBd)Element Loop Length (in) Position (in)ReflectorDriver3 element Yagi (Aluminum tubing Z ~ 42 ohms gain ~ 5 dBd)Element Half Length (in) (0.75 dia dia) Position (in)ReflectorDriverDirector5 element Yagi (Aluminum tubing Feed Z ~ 35 ohms Gain ~ 8 dBd)Element Half Length (in) (0.75 dia dia) Position (in)ReflectorDriverDirectorDirectorDirector
21 Other 6 Meter Antennas Dipole Extended Double Zepp Length = 114 inches (#14 wire) Z ~ 70 ohms Gain ~ 0 dBdExtended Double ZeppLength = 282 inches (#14 wire) Z ~ 45 ohms Gain ~ 4 dbdAntenna is fed at the center through a inch length of 450 ohm ladder line (VF = 0.9)6/10 dual band dipoleLength = 198 inches (#14 wire) Z ~ 64 ohms Gain ~ 1 dBdAntenna is fed at the center through 32 feet 4 inches of 450 ohm ladder line (VF = 0.9)Antenna also can be used on 10 meters (Z ~ 72 ohms)
22 6 Meter Activities Contests Operating Awards Grid Square Hunting ARRL January VHF Sweepstakes (3rd weekend in January)ARRL June VHF QSO Party (2nd weekend in June)SMIRK QSO Party (3rd weekend in JuneCQ WW VHF Contest (2nd weekend in July)Six Club 6 m Sprint (3rd weekend in July)ARRL September QSO Party (2nd weekend in September)Operating AwardsVUCC – contacts with 100 Grid Squares, not difficultWAS – tough, but not impossibleDXCC – very tough from North America, but it has been doneGrid Square HuntingThere are over 500 grid squares in the continental USNo one has worked them all yet (except perhaps for W5FF)
23 What is a Grid Square?Almost all VHF operating awards and contests involve grid squaresGrid Squares are 2º longitude x 1º latitude sections of the earth’s surface (there are 32,400 in total)Each grid square has a 4 character designator containing 2 letters and 2 numbers.The two letters designate the field. There are 324 fields lettered AA through RREach field is divided into 100 squares numbered 00 through 99The continental US includes grid squares in fields CM,CN, DL, DM, DN, EL,EM,EN, FM and FNMost of Rock Hill is in grid square EM94.