1 Evaluating a QTH for Contesting and DXing Steve London, N2IC

2 Factors to be considered Site Selection Criteria Site Selection Criteria Ionospheric propagation to maximize QSO’s and multipliersIonospheric propagation to maximize QSO’s and multipliers Relative rarity – country, state, prefix …Relative rarity – country, state, prefix … Antenna-friendly government and neighborsAntenna-friendly government and neighbors Antenna-friendly environmentAntenna-friendly environment Cost of living and landCost of living and land AccessibilityAccessibility Availability and cost of resources for assembling stationAvailability and cost of resources for assembling station Quiet receiving locationQuiet receiving location Proximity to non-contesting amenities and employmentProximity to non-contesting amenities and employment Do you really want to live there ?Do you really want to live there ?

3 Evaluating the location What are the propagation characteristics to the desired targets ? What are the propagation characteristics to the desired targets ? What is the effect of local topography ? What is the effect of local topography ? Is there an optimal, realizable antenna system for the location ? Is there an optimal, realizable antenna system for the location ?

4 A property to be considered

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7 How high can that mountain be before it affects my signal ?

8 4.6 degree horizon (tan -1 h/d) How High is that Mountain ? DeLorme TopoUSA

9 What about the curvature of the earth ? H = D 2 / H = Number of feet that object “drops” D = Number of miles from object

10 How strong is my signal….with and without the obstruction ?

11 Case Study Denver-to-JA/UA0/JT Denver-to-JA/UA0/JT 15 meters 15 meters 0100Z 0100Z March 30 March 30 Sunspot Number = 70 (Solar Flux = 120) Sunspot Number = 70 (Solar Flux = 120)

12 Summary of Steps Model the terrain from your QTH in the interesting directions Model the terrain from your QTH in the interesting directions Model your antennas over your terrain Model your antennas over your terrain Model the propagation to your target Model the propagation to your target Compare the propagation to your target with "real" terrain and "real“ antennas vs. "ideal" terrain and "ideal" antennas. Compare the propagation to your target with "real" terrain and "real“ antennas vs. "ideal" terrain and "ideal" antennas.

13 Model the Terrain Paper USGS Topographic Maps Paper USGS Topographic Maps Draw a line from the tower base in the direction of interestDraw a line from the tower base in the direction of interest Plot and read points along the linePlot and read points along the line Painstaking !Painstaking ! Topographic Map Software (i.e. DeLorme TopoUSA) Topographic Map Software (i.e. DeLorme TopoUSA) Easier, but still doesn’t automatically generate dataEasier, but still doesn’t automatically generate data MicroDEM (Internet Freeware and included in ARRL Antenna Book) MicroDEM (Internet Freeware and included in ARRL Antenna Book) Manipulates Digital Elevation Model (DEM) topographic data available free on the internet.Manipulates Digital Elevation Model (DEM) topographic data available free on the internet. Automatically generates azimuth terrain profile filesAutomatically generates azimuth terrain profile files

14 ARRL HFTA

15 ARRL HFTA Model the Antenna over Flat Terrain

16 Model the Antenna over the Actual Terrain

17 2-hop F2 3-hop F2 Transition VOACAP Model the Propagation

degree horizon, 50 foot high monobander over flat terrain VOACAP Put it all together !

19 1 degree horizon, 50 foot high monobander over flat terrain VOACAP

20 Compare !

21 Conclusions Difficult to make sweeping statements based on 1 case study Difficult to make sweeping statements based on 1 case study This single case study would suggest: - The 4.6 % obstruction significantly degrades performance to areas with marginal openings. This single case study would suggest: - The 4.6 % obstruction significantly degrades performance to areas with marginal openings.

22 Useful References Propagation prediction software: Propagation prediction software: VOACAP VOACAP Quick Guide - OH6BG Quick Guide - OH6BG MultiNEC ( ( ACE-HF (Reviewed Nov 2002 QST)ACE-HF (Reviewed Nov 2002 QST) PropMan2000 (Sept 2001 QST)PropMan2000 (Sept 2001 QST) WinCAP (Jan 2003 QST)WinCAP (Jan 2003 QST) Topographic map software: Topographic map software: DeLorme TopoUSA - TopoUSA - MicroDEM – – Terrain analysis software: Terrain analysis software: HFTA (HF Terrain Analysis) – ARRL Antenna Book, 20 th edition,HFTA (HF Terrain Analysis) – ARRL Antenna Book, 20 th edition,

23 N2IC/5 QTH …

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28 What I Have Learned at the New QTH It’s easy to be moderately strong It’s easy to be moderately strong 30’ of height works well on the high bands30’ of height works well on the high bands Not so easy to be REALLY strong Not so easy to be REALLY strong Stacked yagis play predictably on flat terrainStacked yagis play predictably on flat terrain No apparent stacking gain on a mountainNo apparent stacking gain on a mountain Antenna and terrain modeling doesn’t tell the whole story Antenna and terrain modeling doesn’t tell the whole story HFTA has significant issues with complex terrainHFTA has significant issues with complex terrain