Contents
- 1 Why do we use long wire antenna?
- 2 What are the different radio bands?
- 3 Does a long wire antenna need to be grounded?
- 4 Are end fed antennas any good?
- 5 What is the difference between band and frequency?
- 6 Does a long wire antenna need to be straight?
- 7 What kind of radio does a long wire antenna use?
- 8 What happens to the gain of a long wire antenna?
Why do we use long wire antenna?
As the frequency increases, the length of the antenna decreases and vice versa. Hence, the frequency and length are inversely proportional to each other. These long-wire antennas are the basic elements for the construction of V-shaped antennas or the Rhombic antennas.
How does a long wire antenna radiate?
Long Wire / End Fed Wire Antenna Includes: With antennas of this length, the radiation directional pattern shows lobes that align more with the axis of the antenna as the length in wavelengths increases. Ultimately, the maximum radiation, and reception sensitivity aligns with the axis of the antenna.
What are the different radio bands?
ITU
| Band name | Abbreviation | Frequency and Wavelength |
|---|---|---|
| Medium frequency | MF | 300–3,000 kHz 1,000–100 m |
| High frequency | HF | 3–30 MHz 100–10 m |
| Very high frequency | VHF | 30–300 MHz 10–1 m |
| Ultra high frequency | UHF | 300–3,000 MHz 1–0.1 m |
What is the gain of a long wire antenna?
The gain increases in proportion to the number of wavelengths used, assuming the antenna is high above ground. For example, the gain for a 3-wavelength long wire (referenced to a dipole) is 2 dB. A 6- wavelength wire yields a 4.8-dB gain, and a 10-wavelength long wire provides nearly 7-1/2 dB of gain.
Does a long wire antenna need to be grounded?
(A random-wire antenna needs a good ground regardless of how much power you’re running.) A counterpoise is simply a long, insulated wire that attaches to the ground connection on your antenna tuner. The best counterpoise is 1/4-wavelength at the lowest frequency you intend to use.
How long should my wire antenna be?
Wire Lengths for Various Band Combinations The fewer bands, the fewer high impedance regions to avoid. You also want the antenna to be at least 1/4 wavelength long for each band you plan to use. For instance, to work 40m be sure the antenna is at least 10m or 33′ long.
Are end fed antennas any good?
End fed wire antennas can work very well under many circumstances. They have some disadvantages, but with careful installation, they can work well and be particularly versatile offering multi-band operation.
What radio frequency is harmful to humans?
Most mobile operators use from radiofrequency waves in the range up 300 MHz to 3 GHz that can be harmful for human health (1).
What is the difference between band and frequency?
A frequency band is a range of frequencies. They’re usually referred to by the wavelength (e.g. 40 meters is the band from 7000 KHz to 7300 KHz). A frequency is the reference point for tuning your transceiver.
How long should a long wire antenna be?
It is important to use a counterpoise. A standard recommendation (see QST, March 1936, p. 32, “An Unorthodox Antenna”) is an 84′ long end fed and a 17′ long counterpoise (6.5′ for 20m)….Wire Lengths for Various Band Combinations.
| Group | USA Bands |
|---|---|
| a | 40-30-20-15 |
| b | 40-30-20-17 |
| c | 40-30-20-17-15-12-10 |
| d | 80-40-30-20-17-15-12-10 |
Does a long wire antenna need to be straight?
The wire may be straight or it may be strung back and forth between trees or walls just to get enough wire into the air. Such antennas are usually not as effective as antennas whose length is adjusted to resonate at the wavelength to be used.
How long can an antenna ground wire be?
You can use any size wire for your antenna ground as long as it’s larger than 10 AWG (and smaller than your house ground. They sell various clamps and wires online at Amazon. You want to be sure to get a solid copper wire, as stranded wire can become brittle over time.
What kind of radio does a long wire antenna use?
The “long wire” antenna is an HF antenna, and operates in the 2 to 30 Mhz band. Not all aircraft will use them, only aircraft that need to communicate further than a VHF radio.
How tall does a long wire antenna need to be?
While the below described antenna does not fit the criteria for a true long wire antenna on the lower bands it will on the higher band above 20m and certainly meets the definition at 10m.
What happens to the gain of a long wire antenna?
As the long wire antenna becomes longer in terms of its wavelength, so the main lobes fall increasingly in line with the axis of the antenna wire. The gain of the antenna also increases as the lobes become more directive with increasing number of wavelengths.
What kind of radio frequency does an airplane use?
Knowing that modern aviation radio operates in the 108-137 MHz band, and that most modern aircraft use much shorter rigid antennas, the long wire would seem to be inappropriate or unnecessary for that purpose. So, why would aircraft of a more modern design still be equipped with one?