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Ham Radio Vertical Antennas

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This presentation is about Amateur Radio Vertical antennas and was used with my talk to a local radio club in Napier New Zealand in 2014

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Ham Radio Vertical Antennas

  1. 1. Vertical AntennasVertical Antennas Do they radiate equally poorly in all directionsDo they radiate equally poorly in all directions or are they simply getting bad press?or are they simply getting bad press? And why vertical antennas?And why vertical antennas?
  2. 2. You Need to Know about Angle of RadiationYou Need to Know about Angle of Radiation Angle of radiation is not just a theory…Angle of radiation is not just a theory… It’s real – if you want to work DXIt’s real – if you want to work DX High angle of radiation – Little or no reflection and no DXHigh angle of radiation – Little or no reflection and no DX Low angle of radiation – good reflection and you work the DX!Low angle of radiation – good reflection and you work the DX!
  3. 3. Propagation gets messy – Why?Propagation gets messy – Why?  Because propagation varies – Hour by hour…. DayBecause propagation varies – Hour by hour…. Day by day…. Month by month and Year by Yearby day…. Month by month and Year by Year  Amateurs ride and live for the solar cycleAmateurs ride and live for the solar cycle  Have a look at what happens to our bands everyHave a look at what happens to our bands every day……..day……..  And then let’s get back to “Why Verticals?”And then let’s get back to “Why Verticals?”
  4. 4. Why Verticals?Why Verticals?  Vertical antennas give low angles of radiationVertical antennas give low angles of radiation  Vertical antennas are easy to constructVertical antennas are easy to construct  Vertical antennas have small “footprints”Vertical antennas have small “footprints”  Vertical antennas are vertically polarizedVertical antennas are vertically polarized  And so is atmospheric and man madeAnd so is atmospheric and man made noise!noise! Let’s look at what makes a vertical antenna work!Let’s look at what makes a vertical antenna work!
  5. 5. Let Us Digress & Talk About Free Space Dipole Radiation Patterns
  6. 6.  Where is current maximum in a half wave antenna?Where is current maximum in a half wave antenna?  Where is current maximum in a quarter wavelength vertical antenna?Where is current maximum in a quarter wavelength vertical antenna?  Why is the current important at the feedpoint?Why is the current important at the feedpoint? Current & Voltage distribution in AntennaCurrent & Voltage distribution in Antenna ElementsElements
  7. 7. Height Above Ground Matters!!! Your 3.6 Mhz dipole is 10 metres above ground and you are feeding it with 72 ohm RG59. It’s perfectly matched – Right? Wrong! – 10m (33’) is actually 0.13 wavelengths above ground. The impedance at the feedpoint is ______ ohms and the mismatch is _________
  8. 8. Practical vertical antennasPractical vertical antennas
  9. 9. The Ground Plane Antenna Power is applied to the base of the vertical radiator and the centre of the four ground plane wires The Marconi Antenna Power is applied to the base of the vertical radiator and the centre of the four ground plane wires
  10. 10. Good Ground – Bad GroundGood Ground – Bad Ground The choice is working your next door neighbour or great DXThe choice is working your next door neighbour or great DX
  11. 11. Radials & Grounds - There isRadials & Grounds - There is No FreeNo Free Lunch!Lunch! So what are we seeing here?So what are we seeing here? Look at the angle of radiation!Look at the angle of radiation!
  12. 12. The more radials you have, the less distance between radials and therefore less loss through the earth. This type of loss is called “ground loss” 4 radials is barely OK. 16 radials is acceptable and 64 radials is heroic and the vertical will sing! Who said “Radials”?Who said “Radials”?
  13. 13. G3AMN 4 Square Grounding SystemG3AMN 4 Square Grounding System
  14. 14. The more Radials – The BetterThe more Radials – The Better
  15. 15. • At least 16 radials should be used if at all possible. 16 radials decreases the loss resistance and increases the antenna efficiency by 30% to 50% for a 1/4 λ vertical, depending on soil characteristics. • Large number of radials (even though some or all of them must be short) is preferable to a few long radials for a vertical antenna mounted on the ground. • The conductor size is relatively unimportant. #12 to #22 copper wire is suitable. • Seawater is great for verticals! • An all metal ground plane such as a large tin roof or a chicken wire matt is excellent as a ground plane base • Anything is better than a 3 foot ground rod !!!!!!!! Practical Suggestions for Vertical Grounds SystemsPractical Suggestions for Vertical Grounds Systems
  16. 16. GAPs, Comets, Cushcrafts &GAPs, Comets, Cushcrafts & JoysticksJoysticks SPECIFICATIONS o Bands + 80m 40m 20m 15m 12m 10m 6m 2m o Bandwidth -- Under 2:1 + Entire band on 40m 20m 15m 12m 10m 6m 2m + 80m over 130 KHz; 10m over 1MHz o Height -- 31.5 ft. o Weight -- 18 lbs. o Radiation Efficiency : Exceed conventional verticals by up to 600% o Mount : Ground or elevated. A ground mount is supplied. o Counterpoise : 3 at 25 ft. o Ground Area Required : Fits in 10 ft. by 12 ft. area. CQ tested the Challenger and established that on 2m, for example, its gain was approximately 6 to 8dB. On 40m compared to a mono band vertical, they found Challenger an S unit stronger. This is typical of the many reports received from amateurs around the world. Challenger is designed to be mounted directly in the ground or elevated. A ground mount is provided with each antenna. With the ground mount in place, the Challenger simply drops in. If necessary, because of space limitations, but not to improve performance, Challenger may be roof mounted since it does not require earth loss to obtain a 50 ohm match. Challenger requires a counter poise of three 25ft. insulated wires. They may be buried or just scattered on the ground. Symmetrical deployment is not critical. Adding additional wire will not significantly improve performance. What are these guys on ????????? GAP VerticalGAP Vertical
  17. 17. What a dream antenna!!! All bands, No radials, No antenna tuner No traps, No coils and 23 feet long Read the fine print – that is what it is designed for – to satisfy the thousands of frustrated apartment dwellers around the world and make money for Comet. Does the antenna work? Yes… but! The efficiency is such that your 100W will magically turn into about 10 watts! The Comet Antenna
  18. 18. CUSHCRAFT R5 (10/12/15/17/20m) Cushcraft have made many vertical antennas; R4, R5, R6, R6000, R7, R7000, R8 etc. All are ½ wave radiators with 4 or shorter base-load rods. Those "radials" are in fact a top hat capacitance. “The 17ft half wave vertical is covering the 10, 12, 15, 17, and 20m amateur bands. The antenna does not require traditional ground radials, so no need for unsightly radials and is so light a normal scaffold pole would be ideal to mount the antenna.” (Sounds good!!!)
  19. 19. DX Engineering’s 55’ 80m/75m/40m dual band vertical. This is a no nonsense antenna and is designed for 16 plus radials. Note the small 40m trap at the 33’ level. With a good radial system installed this antenna would have an efficiency of 80% or more DX Engineering’s 43’ all band vertical. This is a compromise antenna designed for 16 plus radials for 80m – 10m . Note the small automatic tuner below which switches in a tuning network for each of the 8 bands so that the end of the coaxial cable sees a close 1:1 match and 50 ohms so little or no cable loss results.
  20. 20. The All Band, All Singing,The All Band, All Singing, All Dancing Trap VerticalAll Dancing Trap Vertical • Each Trap acts like and “Open Circuit” switch • The 10 Metre radiating part of the antenna is from the top of the mounting pole to the bottom of the 10M trap • The 15 Metre radiating part of the antenna is from the top of the mounting pole to the bottom of the 15M trap • The 20 Metre radiating part of the antenna is from the top of the mounting pole to the bottom of the 20M trap • The 40 Metre radiating part of the antenna is the whole structure from the top of the mounting pole to the bottom of the 40M added section on top of the 20M trap • Note the “Top Hat” on top of the 20M trap. It simply adds inductance so that the whole antenna resonates on 40M
  21. 21. The Biggest “Con” of them all – The “Joystick”The Biggest “Con” of them all – The “Joystick” D r a w in g o f J o y S t ic k s h o w in g le n g t h s , c o il a n d w o o d e n d o w e l. C o il is c o n n e c t e d o n e a c h e n d t o a lu m in u m t u b in g . Amongst the many claims for the Joystick was that it would work indoors propped up in the corner of the room, didn’t require any radials and the advertisements showed glowing testimonials from satisfied DXers that had worked the world with 5 Watts. Partridge Electronics in England sold thousands of them before word got around and the product no longer sold. How gullible are we hams when we look at antennas advertisements???
  22. 22. The VE3EJ 80M 4 Square AntennaThe VE3EJ 80M 4 Square Antenna Just outside Toronto, OntarioJust outside Toronto, Ontario
  23. 23. Vertical Antenna Q & AVertical Antenna Q & A  Do Vertical Antennas Work?Do Vertical Antennas Work?  Answer –Answer –  Can you get away without a good ground system?Can you get away without a good ground system?  Answer –Answer –  Are commercial vertical antennas worth the money?Are commercial vertical antennas worth the money?  Answer –Answer –  What should vertical antennas be used for?What should vertical antennas be used for?  Answer –Answer –  Is it time for me to Finish?Is it time for me to Finish?  Answer – YES!!!!!!!!Answer – YES!!!!!!!!
  24. 24. Beware!Beware! Low flying aircraft!Low flying aircraft! ZM2M - 2009ZM2M - 2009

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