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Found a great formula related to diameter of dipole's rod, suggest and help me!

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Willen

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Wow! Found a great detailed formula related to diameter of dipole's rod, suggest me!

Actually I found a link which is fully dedicated to diameter of dipole's rod calculation. Look in Formula-II. I never found this type of detailed math anywhere related to diameter factor. So I think it will be very useful to me. Because I am going to use 1.8 cm diameter pipe as a rod for 100MHz. www.braincambre500.freeservers.com/Open Half Wave Dipole Calculation.htm
Does it really useful to me? Tell me something please!

Ops...! Why formula-I is 492/MHz? I have found 468/MHz in various places.
Thanks
 
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this (formula i) is the half wave length calculation to find the required length of wire in FEET for an antenna. this is NOT the element diameter. the element diameter (in fractions of a wavelength) determines the usable bandwidth of the antenna, which is what formula ii is used for.

the difference between the 468 number and the 492 number, is that to get the correct length, you need to know the velocity factor of the wire or cable being used. with regular copper wire, the velocity factor is 0.95. with some transmission line elements the velocity factor can be as low as 0.6. 468/f is the wavelength in free space. 492/f is the wavelength on a wire dipole (as the result is 95% of 468/f)

468/f is often used in textbooks for antenna length because: a) it's easier to remember, and b) you can trim wire off an antenna to tune it a lot easier than adding wire to one that's too short
 
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the difference between the 468 number and the 492 number, is that to get the correct length, you need to know the velocity factor of the wire or cable being used. with regular copper wire, the velocity factor is 0.95. with some transmission line elements the velocity factor can be as low as 0.6. 468/f is the wavelength in free space. 492/f is the wavelength on a wire dipole (as the result is 95% of 468/f)

468/f is often used in textbooks for antenna length because: a) it's easier to remember, and b) you can trim wire off an antenna to tune it a lot easier than adding wire to one that's too short

Where is the application of this velocity factor in dipole math? Is it 'Multyplying Factor K or A'?
Ex.- length of dipole in meter= 150xA/MHz (is this?) Or half wavelength multiplied by velocity factor? Like:- 64.56'' x 0.96?

Give me clear way to calculate dipole length. I am using coax as a feed line and 1.8cm diamerer rod for 91 MHz.
 
the velocity factor is applied to the dipole length. if you are making a dipole out of wire, or solid bar or tubing, the velocity factor is 0.95. if you are making a folded dipole or a bazooka antenna out of transmission line, the velocity factor is whatever the velocity factor is for that transmission line.
 
the velocity factor is applied to the dipole length. if you are making a dipole out of wire, or solid bar or tubing, the velocity factor is 0.95. if you are making a folded dipole or a bazooka antenna out of transmission line, the velocity factor is whatever the velocity factor is for that transmission line.
- Actually what you mean by ''Transmission line''? Is it feed line (coax) or antenna tube?
-I am making Open Dipole. OK then should I have to calculate like this-
492x0.95/MHz or 468x0.95/MHz, which is correct?

-What is the impedance of Yagi Uda antenna used folded dipole and Open dipole? Are they same?
Can I use TV's Yagi on my FM, without modifying?
 
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- Actually what you mean by ''Transmission line''? Is it feed line (coax) or antenna tube?
-I am making Open Dipole. OK then should I have to calculate like this-
492x0.95/MHz or 468x0.95/MHz, which is correct?

-What is the impedance of Yagi Uda antenna used folded dipole and Open dipole? Are they same?
Can I use TV's Yagi on my FM, without modifying?

it would be (468/Mhz)x0.95, or (492/Mhz)

a folded dipole has an impedance of 300 ohms and requires a 4:1 balun to match to 75 ohms. an open dipole has an impedance between 50 and 75 ohms, and can be connected directly to the coax
 
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