KPMDWhistler
Member
I am very new to building antennas, and antennas in general. I am also not super knowledgeable with radios, so any help would be greatly appreciated.
So, I want to start planning out my LPDA build, but I'm unable to find any instructions anywhere on how to build one. I have found a website that helps me calculate everything I need to build the antenna. There is a very high likelihood that some of the things that I input wouldn't make much sense, so if you can please give me feedback so I can better understand this tricky subject.
Website: Log‑Periodic Dipole Array Calculator
Input:
Lowest Freq - 100 MHz
Highest Freq - 1000MHz
Diameter of shortest element - 10mm (I wasn't too sure what to put here, I figured 10mm might be a good middle-ground)
Char. input imp. - 50 ohm
Taper - 0.88 (I don't know what this is or how to use it.)
Relative spacing - 0.06 (I don't know what this is or how to use it.)
Output: (Not all outputs included)
Optimal spacing - 0.163 (I assume this is in mm)
Cot of the apex half-angle - 2.000 deg
Number of elements - 21 (Wouldn't it have to be an even number? Or should I just round it to 22?)
Boom Length - 1.383m (54.45")
Length of the dipole element - 1.499m
Distance between element centers - 0.180m
I have not included many things that are probably important, so I would suggest inputting the same variables into the calculator that I provided.
A few more questions:
What does the "Length of the terminating stub []_Zterm = 0.375 m" mean?
What does the "Required characteristics impedance of the feeder connecting the elements Zc_feed = 406.7 ohm" mean?
I assume I don't just straight connect a coax cable to the element loop, what would I use between the element loop and coax cable to the radio?
What would be the recommended element diameter and material?
Would I use some type of aluminum box rod for the boom? If so, what size?
The antenna is not going to be mounted outside, it will be stored inside until I need to use it. When in use it will be vertically mounted to a tripod with a wide stance using hose clamps or a 3/8" fitting.
Any YouTube video links that will help me to better understand what i'm doing would be appreciated.
If my grammar is unreadable, or you need me to clarify anything, let me know.
So, I want to start planning out my LPDA build, but I'm unable to find any instructions anywhere on how to build one. I have found a website that helps me calculate everything I need to build the antenna. There is a very high likelihood that some of the things that I input wouldn't make much sense, so if you can please give me feedback so I can better understand this tricky subject.
Website: Log‑Periodic Dipole Array Calculator
Input:
Lowest Freq - 100 MHz
Highest Freq - 1000MHz
Diameter of shortest element - 10mm (I wasn't too sure what to put here, I figured 10mm might be a good middle-ground)
Char. input imp. - 50 ohm
Taper - 0.88 (I don't know what this is or how to use it.)
Relative spacing - 0.06 (I don't know what this is or how to use it.)
Output: (Not all outputs included)
Optimal spacing - 0.163 (I assume this is in mm)
Cot of the apex half-angle - 2.000 deg
Number of elements - 21 (Wouldn't it have to be an even number? Or should I just round it to 22?)
Boom Length - 1.383m (54.45")
Length of the dipole element - 1.499m
Distance between element centers - 0.180m
I have not included many things that are probably important, so I would suggest inputting the same variables into the calculator that I provided.
A few more questions:
What does the "Length of the terminating stub []_Zterm = 0.375 m" mean?
What does the "Required characteristics impedance of the feeder connecting the elements Zc_feed = 406.7 ohm" mean?
I assume I don't just straight connect a coax cable to the element loop, what would I use between the element loop and coax cable to the radio?
What would be the recommended element diameter and material?
Would I use some type of aluminum box rod for the boom? If so, what size?
The antenna is not going to be mounted outside, it will be stored inside until I need to use it. When in use it will be vertically mounted to a tripod with a wide stance using hose clamps or a 3/8" fitting.
Any YouTube video links that will help me to better understand what i'm doing would be appreciated.
If my grammar is unreadable, or you need me to clarify anything, let me know.
Last edited: