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DB is right on the money. That's two 3 element vertical beams. The driven element is a folded dipole. The good question is why are the director and reflector angled the way they are. There can only be a few reasons for this. My first thought was they are angled to prevent them from arcing to the ground. This guy runs in excess of 50 kw! These pictures were taken at a event in Florida a year or two ago where he proceeded to kick the snot out of all the competition. The folded dipole will not develop a corona arc on its ends because it has no ends for the high voltage RF to discharge in an arc. By angling the outside elements he has gained some ground clearance on them.

Then I remembered he's combining a pair of folded dipoles together that without parasitic elements would have an impedance of about 300 ohms each or 150 ohms together. There are no impedance adjustments on his driven elements. He could have used a pair of T-matches to tap the driven elements at the correct impedance. He could have used different diameter tubing to form each side of the folded dipole, thereby allowing you to adjust impedance by the gapping distance of the folded dipole. I think he decided to pull the bottoms of the parasitic elements in towards the folded dipole in order to cause the impedance of the system to drop closer to 50 ohms. Simply moving the entire reflector and director elements closer to the driven would do the same thing but could reduce gain too.

I've thought about the possibility of some type of mechanical beam tilt taking place and can pretty much rule that out as a possibility. At this wavelength and low height above ground, tilting the elements will not tilt the radiation angle in the far field. The ground is going to reflect this signal back up to the same take off angle as we would have without the elements tilted at this height above ground. Furthermore, both outside elements are tilted at opposing angles and have similar currents on them. Any effect one could have would be cancelled by the other. He's most likely adjusting his SWR by tilting these elements.

<blockquote data-quote="Shockwave" data-source="post: 431516" data-attributes="member: 10882">DB is right on the money. That&#039;s two 3 element vertical beams. The driven element is a folded dipole. The good question is why are the director and reflector angled the way they are. There can only be a few reasons for this. My first thought was they are angled to prevent them from arcing to the ground. This guy runs in excess of 50 kw! These pictures were taken at a event in Florida a year or two ago where he proceeded to kick the snot out of all the competition. The folded dipole will not develop a corona arc on its ends because it has no ends for the high voltage RF to discharge in an arc. By angling the outside elements he has gained some ground clearance on them.Then I remembered he&#039;s combining a pair of folded dipoles together that without parasitic elements would have an impedance of about 300 ohms each or 150 ohms together. There are no impedance adjustments on his driven elements. He could have used a pair of T-matches to tap the driven elements at the correct impedance. He could have used different diameter tubing to form each side of the folded dipole, thereby allowing you to adjust impedance by the gapping distance of the folded dipole. I think he decided to pull the bottoms of the parasitic elements in towards the folded dipole in order to cause the impedance of the system to drop closer to 50 ohms. Simply moving the entire reflector and director elements closer to the driven would do the same thing but could reduce gain too.I&#039;ve thought about the possibility of some type of mechanical beam tilt taking place and can pretty much rule that out as a possibility. At this wavelength and low height above ground, tilting the elements will not tilt the radiation angle in the far field. The ground is going to reflect this signal back up to the same take off angle as we would have without the elements tilted at this height above ground. Furthermore, both outside elements are tilted at opposing angles and have similar currents on them. Any effect one could have would be cancelled by the other. He&#039;s most likely adjusting his SWR by tilting these elements.</blockquote>

[QUOTE="Shockwave, post: 431516, member: 10882"] DB is right on the money. That's two 3 element vertical beams. The driven element is a folded dipole. The good question is why are the director and reflector angled the way they are. There can only be a few reasons for this. My first thought was they are angled to prevent them from arcing to the ground. This guy runs in excess of 50 kw! These pictures were taken at a event in Florida a year or two ago where he proceeded to kick the snot out of all the competition. The folded dipole will not develop a corona arc on its ends because it has no ends for the high voltage RF to discharge in an arc. By angling the outside elements he has gained some ground clearance on them. Then I remembered he's combining a pair of folded dipoles together that without parasitic elements would have an impedance of about 300 ohms each or 150 ohms together. There are no impedance adjustments on his driven elements. He could have used a pair of T-matches to tap the driven elements at the correct impedance. He could have used different diameter tubing to form each side of the folded dipole, thereby allowing you to adjust impedance by the gapping distance of the folded dipole. I think he decided to pull the bottoms of the parasitic elements in towards the folded dipole in order to cause the impedance of the system to drop closer to 50 ohms. Simply moving the entire reflector and director elements closer to the driven would do the same thing but could reduce gain too. I've thought about the possibility of some type of mechanical beam tilt taking place and can pretty much rule that out as a possibility. At this wavelength and low height above ground, tilting the elements will not tilt the radiation angle in the far field. The ground is going to reflect this signal back up to the same take off angle as we would have without the elements tilted at this height above ground. Furthermore, both outside elements are tilted at opposing angles and have similar currents on them. Any effect one could have would be cancelled by the other. He's most likely adjusting his SWR by tilting these elements. [/QUOTE]

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