The quarter-wave antenna in the industry radio should be regarded as the simplest and not bad antenna, so it occupies a considerable proportion in the radio industry. For example, if you pay attention, most of the antennas on police cars It is a quarter-wavelength antenna like the 430MHZ mobile phone you are using. Most of its antennas are also quarter-wavelength. Please note that most of the big mobile phones are also quarter-wavelength. The wavelength of the antenna shows that the quarter-wavelength antenna definitely has its effect. If you are not a concept of electronics, you may ask what is the quarter-wavelength? Simply put, it is an antenna The unit of length is calculated in terms of frequency. It has a formula:

The length of the antenna (wavelength) = 300 divided by the frequency multiplied by a quarter and multiplied by 0.96 (wavelength shortening rate) is

The calculated length of the antenna (in meters) For example, if you want to make an antenna with a frequency of 144.00MHZ, you must first calculate the antenna length and then use the above formula to calculate: (300 / 144.00MHZ) * 0.25 * 0.96 = 0.5 (meter)

So we get 0.5 meters, which is 50 cm in length. Then we need to prepare materials. We prepare 5 50 cm copper bars and an M-shaped connector (see Figure 1). Then use a soldering iron to connect the M-shaped main shaft to one of them. The copper bars are welded together, and the other four are screwed on the sides or welded, and the four are down 45 degrees

There is a relatively simple method of making GP antennas, and there are several methods of attachment.

The following is a physical photo quoting netizen "MXX"

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Anti-Explossion Matte Films

What are the advantages of Explosion-proof Screen Protectors?
What is an Explosion-proof Screen Protector? This is a Soft Film made of imported PET material. It has very good flexibility and can help you solve the problems of tilting, white edges, and not suitable for curved screens. Can closely fit the curved edge of the screen.
The PET Screen Protector is made of imported materials from Korea. It is equipped with a proprietary "self-healing" function that can automatically repair minor scratches on the film. Daily protection measures to prevent accidental knocks and drops. The screen strengthens the screen and reduces the chance of cracking. Broken tempered glass is no longer replaced frequently.
1. Edge coverage: The Explosion-proof Screen Protective Film is made of PET flexible material, which is very suitable for the screen of your device, and 100% provides excellent edge coverage, and there is no gap between the edges of the device
2. High-definition resolution: high-definition display, true display of the original screen color.
3. Original touch experience: The oleophobic coating surface of the screen protector can provide your phone with original texture and perfect touch screen response speed. The Soft Film also has oleophobicity and water resistance, which can prevent unnecessary fingerprints.
4. Self-repairing scratches: The Screen Protection Film with self-repairing function can automatically repair tiny scratches and bubbles within 24 hours.
5. Anti-seismic and explosion-proof: PET material has high strength, flexibility and elasticity, which can fully decompose the impact force and prevent the mobile phone from breaking

Explosion-Proof Matte Protective Film,Matte Explosion-Proof Screen Protector,Anti-Scratch Matte Film,Anti-Impact Matte Film

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