GP vertical antenna radiation diagram
GP vertical antenna radiation diagram
The figure commonly used in cheap FM transmitter GP antenna, within the price of one hundred yuan. Cone antennas are described below.
GP antenna in English stands for: Ground Plane Antenna, that is, “with a ground plane antenna”, also known as “ground plane antenna” or simply “ground antenna.”
GP antenna is in the U / V segment to communicate the type most commonly used antennas, his family members, including a car whip antenna, fiberglass base antennas, small antennas on handheld devices and so on. Since the U / V segment in the use of vertical polarization communication mode, the antenna usually be set up vertically, so the antenna is also called “vertical grounded antenna.”
First, we take a look and lobe antenna radiation diagram, in which the blue object on behalf of the antenna oscillator, green translucent objects representative of radiation lobe. We can see: In a typical monopole antenna work, the electromagnetic radiation similar to an apple shape, dipole antennas electromagnetic wave around the average distribution of non-directional. This is a simple vertical antenna radiation.
Vertical antenna radiation model
Sometimes, we hear about the gain and directional antennas, the following chart to show when two superimposed oscillator generated by change. Can be seen: when two superimposed oscillator, the lobe shape becomes flat some of the radiation energy is more concentrated in the horizontal direction, which formed in the horizontal direction of the gain of the antenna to improve the “efficiency”, now City fiberglass base antenna, sold most of this structure, there are a lot of friends made according to this principle of high-gain antenna. Of course, to make the antenna have a way to gain not only this, not much discussed here.
Understanding antenna radiation, let us look at the case of GP antenna.
GP antenna is generally fed by a coaxial cable, inner conductor of vibration sub, outer conductor connected to “ground plane.” “Ground plane” is what we often say “to network.” The figure is a typical GP antenna ground plane to infinity, the radiation situation, the basic wave radiation along the horizontal direction, this is the ideal state.
Ideal state of radiation
However, in the manufacture of the antenna, we can not do the infinite ground plane must be reduced to the extent that we can afford, but that also caused a change of direction of radiation. The figure is the diameter of the ground when connected to four times shorter wavelength case: the maximum radiation direction left the ground plane tilts up.
A radiation angle of elevation
Bottom: When the ground plane is further reduced when the radio emissions of up to 30 degrees elevation.
Elevation B radiation
Expected to make waves in accordance with the way radiation people, people come up with a lot of ways to avoid the above-mentioned situation. The figure is an example: the shape of the ground plane to the cone, the radiation under control.
To net radiation model
Shown below is our most commonly seen in vehicle whip antenna model. Adsorbed on the roof with a sucker in, although radiation is still on Yang, but because the body of the metal plate to act as a “ground plane”, radiation has been well controlled.
Antenna radiation model used car
In use, the card edge with some friends the antenna fixed in the car, but this time due to the uneven distribution of electric field, will reduce the antenna efficiency. So I think: the best antenna on the roof with a central sucker adsorption, it is a good distribution of the average electric field, allowing the antenna to play the greatest efficiency.
GP antenna in addition to the above said fiberglass base antenna and the car whip antenna, there are other different forms.
Such as: using a radius of 1 / 4 wavelength of the disc instead of 1 / 4 wavelength vertical dipole, composed of the following with conical ground plane antenna for the disc cone (Kandoian), disc cone antenna to a very large bandwidth, the maximum radiation direction always along the horizontal direction.
Another example: In 1938, George H. Brown and Jess Epstein & Robert Lewis with four 1 / 4 wavelength ground plane conductor instead of entity to form a fiberglass base antenna is similar to the form. In this form the basis, as the improvement in the antenna feed-side in parallel a 1 / 4 wavelength short-circuit coaxial cable, which not only broadens the impedance bandwidth, and protection in the event of lightning when the shock wave transmission line.
In addition, the commonly used hand-held mobile devices and scalable whip antenna (commonly known as rod antenna) is also a GP antenna, the antenna has the advantage that the oscillator length of the variable at any time, can work in different bands.
Now, more and more friends to join the ranks HAM, received a radio license and is ready for examination Communications card was promoted by three. At this time, the problem comes: Communications card with “antenna” (ANT) column, do not know how to fill out. In fact, on this issue I have with many friends in the frequency of exchange before, here and then explain: fiberglass base antennas, vehicle whip antenna, handheld mobile communications devices whip the most common antennas are all GP antenna, if you using this type of antenna, as long as the “antenna” field fill “GP” can, if you are using a “Yagi – Uda” antenna, you fill out the “YAGI”, if you want to tell each other you are using 14 unit “Yagi – Uda” antenna, then the “14 ELE YAGI” is the correct representation.