Dipole its symmetric system with ~72ohm in center.
Wiki:
The dipole is any one of a class of antennas producing a radiation pattern approximating that of an elementary electric dipole with a radiating structure supporting a line current so energized that the current has only one node at each end.
The most commonly used is the center-fed half-wave dipole which is just under a half-wavelength long. The radiation pattern of the half-wave dipole is maximum perpendicular to the conductor, falling to zero in the axial direction, thus implementing an omnidirectional antenna if installed vertically, or (more commonly) a weakly directional antenna if horizontal
A half-wave dipole antenna consists of two quarter-wavelength conductors placed end to end for a total length of approximately L = λ/2. The current distribution is that of a standing wave, approximately sinusoidal along the length of the dipole, with a node at each end and an antinode (peak current) at the center (feedpoint)
How to build half-wave dipole antenna for hf:
1.Need 2 copper wire 1-4mm diameter and λ/4– use this table:
Wavelength table
Band | MHz | λ | λ/2 | λ/4 |
160 meter | 1,81 MHz | 165,75 Meter | 82,87 Meter | 41,44 Meter |
80 meter | 3,6 MHz | 83,33 Meter | 41,66 Meter | 20,83 Meter |
60 meter | 5,35 MHz | 56,07 Meter | 28,04 Meter | 14,02 Meter |
40 meter | 7,1 MHz | 42,25 Meter | 21,13 Meter | 10,56 Meter |
30 meter | 10,1 MHz | 29,70 Meter | 14,85 Meter | 7,43 Meter |
20 meter | 14,15 MHz | 21,20 Meter | 10,60 Meter | 5,30 Meter |
17 meter | 18,1 MHz | 16,57 Meter | 8,29 Meter | 4,14 Meter |
15 meter | 21,2 MHz | 14,15 Meter | 7,08 Meter | 3,54 Meter |
12 meter | 24,95 MHz | 12,02 Meter | 6,01 meter | 3,00 Meter |
10 meter | 28,4 MHz | 10,56 Meter | 5,28 Meter | 2,64 Meter |
Note that the shortening factor of the wire is not included in the table. So the antenna will be about 5% shorter in reality.

2. Balun 1:1 (without balun you will be have many common mode. Balun need for current symmetry and choke commonmode)
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Product on saleBalun for dipole 1:1 (DB11K)Original price was: €90.00.€70.00Current price is: €70.00.
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Product on saleBalun for dipole 1:1 (DB1143)Original price was: €80.00.€65.00Current price is: €65.00.
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Product on saleBalun for dipole 1:1 (DB1152)Original price was: €80.00.€70.00Current price is: €70.00.
3. Coax 50ohm 1/2 lamda length (Half-wave coax repeater) – use this link for calculate coax length: (use Freq and shortening factor anly) – https://docs.google.com/spreadsheets/d/1Ww9v5mr89MIzynbZVK-7KeMNxyqpsoXb5VZy7sDfUOY/edit?usp=sharing

Balun 1:1 (without balun you will be have many common-mode. Balun need for current symmetry and choke common-mode)
Balun:
Balun is an electrical device that converts between a balanced signal and an unbalanced signal. Our dipole its strongly balanced device, our coax its unbalanced device.
Balun materials:
Wire copper or silverplated (much better) 0.5-0.7mm 100-300wt
Core:
FT140-43 – 1-10 mhz 10-24 mhz 30-54mhz
FT140-52 – 1-3 mhz 3-30 mhz 54mhz
Wire copper or silverplated (much better) 1.2-1.5mm 500-1000wt
Core:
FT240-43 – 1-10 mhz 10-24 mhz 30-54mhz
FT240-52 – 1-3 mhz 3-30 mhz 54mhz
FT240-K – 1-3mhz 3-54mhz