Construction 2.
Greetings friends! Time for antennas again!
Today I am laying out the construct of one of the simplest antennas - this is the canonical GP antenna 1/4. You can easily find more than one similar design on the Internet, but here I will show my construct.
The design is actually simple. In the detailed photo, you will see all the elements.
The design is based on the correct microwave connector. This is an N-type flanged connector. It is easy to mount and fits in a variety of designs, which I will describe a little later.
For a clean GP antenna, as shown in the photo above, an important element is the absence of a metal mounting cup. If you plan to mount the antenna on a mast, then it must be dielectric or the glass must be no more than 50mm in length.
The emitting element is made of a brass tube with a diameter of 4mm. The length of the radiating element is 82mm. The tube is neatly sealed on the piping of the connector.
I have a counterweight made of soft copper wire with a diameter of 2mm.
The length of the counterweights that are attached to the connector is 75mm.
When you make counterweights, cut the total length of the elements 100 … 120mm. Counterweight fasteners can be made from the same piece of wire or can be soldered onto special petals (see photo).
To minimize the influence of the power cable, a small loop with a diameter of 2 … 3 cm is made below the connector 7 … 10 cm.
Antenna parameters: VSWR, LogMag, Smith.
If you mount the antenna on a metal glass (not recommended), then the length of the radiating element will need to be slightly increased. I used a regular screw for this.
Perform the setting with the NanoVNA V2 device. We achieve a minimum SWR by rotating the screw and changing the angle of the counterweights (about 45 degrees)