Production of "J" antenna under amateur conditions

The J-Pole antenna is composed of a 1 / 2-wave emitter and a 1 / 4-wave drive matching device. It is equivalent to a dipole antenna driven from the end. Because its conductor is J-shaped, it is called For J pole. The right picture A is an example of a J-pole antenna, and B is a J-pole antenna made of copper wire or copper tube with a diameter of 3-10 mm (suitable for high power).

The following introduces a method of making "J" type antennas under amateur conditions, for fans to imitate.

First of all, you can buy the following materials from the refrigeration equipment repair shop: 10mm refrigeration copper tube 3.5m; supporting U-shaped elbow.
Reference price Copper tube: 4 yuan / meter U-shaped elbow: 2 yuan / piece

Let everyone take a closer look at how the U head and copper tube are connected.

Tin the inner and outer walls of the copper tube and the inner wall of the U-shaped head. (It is recommended to grind the sand with fine sand first, apply flux, and tin it with a high-power electric iron)

Then use gas welding or gas stove welding: insert the tin-lined copper tube into the U head, and heat it in the gas furnace at the same time to melt all the tin, adjust the angle, close the furnace, and let the copper tube and tin cool naturally. (Be sure to pay attention to safety)

The part of the feeding point of the well-welded antenna is welded with a 50-5 feeder and the M base.

Complete joints and nodes

If you have a good J-type antenna, if you think the effect is not good, you can also use another section of copper tube and a U-head as a folded part to increase the gain.

Note: The short side of the core wire is conducive to lightning protection!

J-type antenna parameter calculator (English).

There is another design of J-pole antenna (89MHz.pdf format), click to download.

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