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HF OPERATORS

HF OPERATORS. HIGH FREQUENCY TERRAIN ASSESSMENT HFTA and MicroDEM by John White VA7JW va7jw@shaw.ca. What is HFTA ?. Antenna modeling software (i.e. EZNEC) typically models over FLAT TERRAIN

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HF OPERATORS

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  1. HF OPERATORS HIGH FREQUENCY TERRAIN ASSESSMENT HFTA and MicroDEM by John White VA7JW va7jw@shaw.ca NSARC HF Operators

  2. What is HFTA ? • Antenna modeling software (i.e. EZNEC) typically models over FLAT TERRAIN • The physical features of the land at your QTH will alter the flat terrain vertical radiation pattern model • HFTA software models the vertical radiation pattern of your antenna based on your actual terrain ACTUAL TERRAIN ALL DIRECTIONS = 360 degrees NSARC HF Operators

  3. Where to Get HFTA? • HFTA is ARRL proprietary software supplied on a CD which is included with every ARRL antenna handbook since 2003 • It cannot be purchased from ARRL as a stand-alone package nor be downloaded for the web • HFTA was developed by Dean Straw N6VB while employed at ARRL as Senior Technical Editor for many publications • Copy the HFTA files to your PC from the CD • Runs under Windows XP and Win 7 NSARC HF Operators

  4. HFTA Features • HFTA allows experimentation with different antennas at different heights to characterize a given installation, or optimize and design a new installation, at a given location / terrain • Computes horizontally polarized radiation, sorry - no verticals • Dipoles and yagi’s from 2 elements to 6 elements • Heights > 1 foot above ground, at antenna site • Bands from 160 through 10 meters • Shows only low angle radiation < 34 degrees (why later ..) NSARC HF Operators

  5. Vertical Radiation Plots • Example: Vertical elevation plot – dipole - 1 wavelength high over flat terrain • Lobes show angles of maximum gain and minimum gain, (peaks and nulls) • Loss effect of real ground is also noted NSARC HF Operators

  6. Effect of Terrain • Recombination of the Direct wave and ground Reflected wave determines the angle at which max and min lobes appear • Higher the antenna, the lower becomes the first maximum lobe with more lobes developing with increased height • The angles of reflection are also determined by • the distance from the antenna to terrain variations • the angle of the terrain to the antenna – rising, falling, flat … • rising ground will increase low angle, falling will decrease low angle 15 degrees 10 degrees 5 degrees NSARC HF Operators

  7. How Lobes are Formed • Lobes occur due to the phase re-enforcement or cancellation of the direct wave from the antenna and the reflected wave from the ground • (Reflected wave undergoes a 180 deg phase shift since E field must = 0 at t he surface of a conductor, i.e the ground) Formation of a Max Lobe at 50 deg Formation of a Null at 30 deg NSARC HF Operators

  8. Where’s the Terrain Info? • HFTA does not contain terrain / topographical information • HFTA uses a digital topographical mapping application which renders topographical information into a file format suitable for use by HFTA • MicroDEM is the companion mapping software that provides HFTA with the required land profiles for mapping • More on MicroDEM later …. NSARC HF Operators

  9. HFTA – What will it do? • Enter the Type and Height of your antenna above ground • Enter Frequency • Enter the geographical definition of your terrain from MicroDEM • HFTA will calculate the terrain profile every 5 degrees around your QTH out to 4400 m / 14,500 feet • HFTA will plot the vertical angle of radiation of the antenna, • can be compared to flat ground performance • can be compared to the arrival of low angle DX signals NSARC HF Operators

  10. Main HFTA Window • Enter Frequency • Terrain Files • as generated by MicroDEM are loaded here • Ant Type • select the antenna from a drop down menu • Height of Antenna – type in • There are 4 fields so that 4 models can be compared NSARC HF Operators

  11. Completed Window • MicroDEM has generated a profile at a 60 deg AZ from my QTH. 3 element yagi at 60 ft, all entered • Loaded the Flat File that plots patterns of flat terrain • Checked both lines 1 and 4 to plot pattern of same graph NSARC HF Operators

  12. Terrain Profile Plot • Hit the Button Height of Antenna above ground Ground (Terrain) Profile at 60 degrees Azimuth Burrard Inlet – Sea Level Burke Mtn Ridge NSARC HF Operators

  13. Vertical Radiation Plots • Hit the Button • Typical Gain over Flat about 4 to 6 dB out to 20 deg. The Negative Profile advantage • No advantage 14 to 18 degrees • Sharp nulls at 8 & 23 deg • One would experiment with various heights to find optimum performance Antenna Pattern Flat Terrain Pattern NSARC HF Operators

  14. DX Low Angle Skip • Many DX signals arrive at low angles due to long skips • Long skip typically arrives at < 34 degrees (ARRL Antenna Handbook 21st edition, pages 3-21 ff) • Antenna performance for low angle / long skip of particular interest to DX operators • HFTA allows for examination of low angle arrivals with respect to the vertical elevation antenna plot • Enter desired angle coverage in HFTA window. NSARC HF Operators

  15. DX Profile Files • HFTA is supplied with files (.PRN) that provide a statistical angle of arrival of DX signals as a percentage of time that can be plotted along with the vertical radiation pattern • Select your call zone i.e. VE7 from the .PRN file listing • Areas are Africa (AF), South Asia (AS), Europe (EU), Far East (JA), South Pacific (OC), South America (SA), and the US • Select the DX “area” from the list of VE7 files by clicking in the Elevation field of HFTA • The PRN elevation file is entered in to the HFTA main window NSARC HF Operators

  16. The Complete Plot • Introduce the EU file for DX angle of arrival • Bar graph representation • Most often, signals arrive between 3 and 6 degrees • Antenna pattern happens to peak in this area – that’s good • Try other bands, directions • That’s it! except for the mapping …. NSARC HF Operators

  17. Maps and MicroDEM • MicroDEM software loads and displays digital topographical maps • Digital topographical map is called a DEM = Digital Elevation Module (Digital Elevation Map makes more sense) • DEM’s are 3 dimensional topographical providing latitude, longitude and elevation • Canada and US DEM’s are available on the web and are free • MicroDEM processes these maps & provides HFTA with terrain files that allows HFTA to plot the profiles and calculate the vertical radiation patterns NSARC HF Operators

  18. Where to Get MicroDEM? • MicroDEM is downloadable from the web, free • Do NOT download the MicroDEM version from the ARRL CD. It is out of date • Developed by Professor Peter Guth of the US Naval Academy http://www.usna.edu/Users/oceano/pguth/website/microdem/microdem.htm • The latest MicroDEM version is now 64bit • Runs under Windows XP and Win 7 NSARC HF Operators

  19. About MicroDEM • MicroDEM is a powerful and complex application • Do not “experiment” with it as setup is critical • Recommend downloading “Beginners Guide to HFTA” for setup directions and settings to get started http://www.nsarc.ca/tech_archive/Articles/hfta.pdf • Also download “Operating Instructions for HFTA Ver 1.04” by Dean Straw, dated 22 Feb 2013, http://www.arrl.org • or go to the ARRL website, search for HFTA, click on HFTA … NSARC HF Operators

  20. Canadian DEM’s • Access DEMS at http://www.geobase.ca • Geobase > data > digital elevation data • Whole Canada map • Select General Region • i.e. South West Canada, Region 92 • Click on 92 to expand • Region 92 is subdivided • Select Vancouver is 092G • Click to expand again NSARC HF Operators

  21. Expanded DEM • DEM now shows districts within 092G • Click on the NAME closest to QTH • This case Port Coquitlam (PoCo) • Data field below map shows selected DEM file(s) for download • 092G07 is the DEM file for PoCo • This is downloaded to a directory set up by HFTA NSARC HF Operators

  22. Sub-DEM Structure(Canadian only) • Sub sections within 092G are identified by suffixes 01 thru 08 with attached names as shown. Each sub section has an East and West map i.e. demw – DEM west and deme = DEM east NSARC HF Operators

  23. MicroDEM Appearance • Main window • This is a map of the lower mainland, a composite of 8 DEM’s • North shore Mtns • Harbour • Vancouver • New Westminster • Surrey • Richmond, Delta, Ladner NSARC HF Operators

  24. Opening the DEM’s • Refer to Beginners Guide for unzipping and saving the file • When DEM file has been selected, open in MicroDEM • First time may take a moment to interpret • Display is set to represent elevation by color. Blue ~ sea level, red ~ 2000m • Resolution looks miserable but it is not • Magnification can show great detail • MicroDEM will stitch together maps to make larger maps i.e. lower main land VA7JW QTH NSARC HF Operators

  25. Where Am I ? • You have to know where you are located, accurately • Use Google Earth (suggest version 7.1.1.1888 or later) • Enter your street address in the SEARCH field • Magnify and find your house • Zoom in and place cursor on top of your antenna / tower • Lower right, read off your Latitude. Longitude and Elevation i.e. 49 degrees 16 minutes 59.73 seconds North etc., EXACTLY (why?) NSARC HF Operators

  26. Position Accuracy • Profile plots and antenna pattern accuracy are based on position of antenna / tower on the map. Get within 10 ft. • Distances between Latitudes are constant North to South • Distance between Longitudes varies with Latitude North and South of equator > becomes zero at Poles • Table shows uncertainty of location at equator; E-W error becomes less at higher latitudes. NSARC HF Operators

  27. Find QTH on the Map • Write down the Google Earth coordinates • Open up your MicroDEM QTH map • Mouse over estimated QTH • Watch bottom of MicroDEM window for Lat, Long and Elev readings • Move mouse until Lat Long read ~ same as Google Earth Lat & Long • That’s your QTH (VA7JW) NSARC HF Operators

  28. Enter QTH in MicroDEM • Double Click on your QTH • Window appears with Lat and Long of the mouse on map • This does not have to be precisely set on the map • Now enter the exact Lat and Long as per Google Earth in the fields • MicroDEM now knows exactly where your antenna is NSARC HF Operators

  29. FAN Generation • MicroDEM, will generate a land profile, radially from the QTH, every 5 degrees, over 360 degrees, out to 4400 meters • This “suite” of files is referred to as a FAN • Each 5 degree profile is saved as a .PRO file • There is one file for each 5 degree increment (71 in total) • This is the field that will populate the HFTA window under the Terrain Files field (MicroDEM saves these files automatically as degrees (i.e. VA7JW-60.00.PRO) Suggest renaming with date & time stamp i.e. VA7JW-21jun13-1708-60.00.PRO) NSARC HF Operators

  30. HFTA is READY • You can now run HFTA to do your site analysis • Run profiles • Run antenna patterns • There are other very important, useful features in MicroDEM • MicroDEM will plot, • The Blocking Horizon • Topology coverage map • Lines of Sight, useful for VHF/ UHF NSARC HF Operators

  31. The Blocking Horizon • The horizon limits the ultimate angle for blockage of signal, both on transmit and receive • MicroDEM will graph the blocking horizon • Line of Sight – your QTH to the horizon in terms of vertical angle as well as distance to the blockage vs. azimuth • Horizon Blocking Plots • Elevation plot to blocking horizon, over 360 degrees • Distance plot to the blocking horizon, over 360 degrees • Topographical MAP showing areas where blockage occurs NSARC HF Operators

  32. VE7NSR Example • A Topographical map showing blocking horizon • The Vertical elevation plot to the horizon, in degrees • can also run distance to blocking horizon • Reveals problematic areas as well as good areas, by Azimuth • Plot profiles in directions of interest as well as worst & best • Take into account antenna beam width with respect to coverage NSARC HF Operators

  33. VE7NSR Topology • Blocking Horizon from NSEMO out to ~ 20 km NSARC HF Operators

  34. VE7NSR Blocking Horizon Lions Grouse Seymour Cypress Buraby Mtn Vancouver Straits NSARC HF Operators

  35. VE7NSR, the HFTA Plots • PRO files generated • Freq 14.2 MHz • PRO file at 1200, 3 ele yagi at 70ft entered • Flat Terrain file • DX Rx angles .PRN files for South America NSARC HF Operators

  36. Typical 2 Degree Horizon • North Van platform at 120 degrees • Land profile drops, looking up Burrard inlet towards Bby Mtn • Actual is not as good as Flat NSARC HF Operators

  37. Worst Case, 90 Horizon • Grouse blockage • Ant pattern is impaired for Low angle DX • Flat Terrain • DX Arrival Angle NSARC HF Operators

  38. Best Case, 00 Horizon • Negative Horizon, ground slopes away at 2500 • Ant pattern excellent • No blockage of low angle sig arrival. Good for DX NSARC HF Operators

  39. LOS – Bowen Repeater • LOS is Line Of Sight • VHF/ UHF path • Green is visible • Red is obscured Mt Gardner NSEMO NSARC HF Operators

  40. LOS – Seymour Repeater • VHF – UHF Path (actual repeater site – tower uncertain) • and for something really cool > NSEMO NSARC HF Operators

  41. Panoramic View - NSEMO • MicroDEM generates a panorama view that can be scrolled through 360 degrees Lions Grouse Seymour Eagle NSARC HF Operators

  42. DONE • Once the PRO(files) are generated, HFTA is ready to compute • Characterize your location • all antennas (horizontally polarized only) • all heights • all bands • all directions • Vancouver has a complex horizon - good and no so good for DX • plot your horizon as shown slide 34 • know which parts of the world are at what azimuth, slide 34 • blockages mean low angle will be impaired but under most openings, higher angle is common and DX will be worked NSARC HF Operators

  43. Summary • HFTA and MicroDEM will provide a characterization of your antenna vertical radiation patterns as altered by local terrain at your QTH • HFTA software is easy to use • MicoDEM mapping software takes effort to setup • To make this task EASIER download “Beginners Guide to HFTA and Microdem” at: http://www.nsarc.ca/tech_archive/Articles/hfta.pdf • Provides step x step instructions NSARC HF Operators

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