1, antenna efficiency

It is the ratio of the power radiated from the antenna (i.e., the power of the effective conversion of electromagnetic wave part) and the active power input to the antenna. Is constant less than 1 value.

2, antenna polarization wave

Electromagnetic wave propagation in space, if the direction of the electric field vector remains fixed or rotate according to certain rules, this electromagnetic wave is called polarization wave, also known as antenna polarization wave, or polarization wave. Usually can be divided into plane polarization (including horizontal polarization and vertical polarization), circular polarization and elliptical polarization.

3, polarization direction

The direction of the electric field of polarized electromagnetic waves is called the direction of polarization.

4、Polarization surface

The plane formed by the polarization direction and propagation direction of the polarized electromagnetic wave is called the polarization plane.

5、Vertical polarization

The polarization of radio waves, often using the earth as the standard surface. Where the polarization surface and the earth normal surface (vertical surface) parallel to the polarization wave is called vertical polarization wave. Its electric field direction is perpendicular to the earth.

6、Horizontal polarization

Where the polarization surface and the earth normal surface perpendicular to the polarization wave is called horizontal polarization wave. Its electric field direction is parallel to the earth.  

7、Planar polarization

If the polarization direction of the electromagnetic wave remains in a fixed direction, it is called plane polarization, also known as line polarization. In the component of the electric field parallel to the earth (horizontal component) and perpendicular to the surface of the earth, its spatial amplitude has an arbitrary relative size, you can get the plane polarization. Vertical polarization and horizontal polarization are special cases of planar polarization.

8、Circular polarization

When the angle between the polarization surface of the radio wave and the earth normal surface varies from 0 to 360 ° period, that is, the electric field size is constant, the direction changes with time, the trajectory of the end of the electric field vector in the plane perpendicular to the direction of propagation projection is a circle, called circular polarization. Circular polarization can be obtained when the horizontal and vertical components of the electric field are equal in amplitude and differ in phase by 90° or 270°. Circular polarization, if the polarization surface rotates with time and becomes a right spiral relationship with the electromagnetic wave propagation direction, called right circular polarization; conversely, if it becomes a left spiral relationship, called left circular polarization.

9、Elliptic polarization

If the radio wave polarization surface and the angle between the earth normal surface from 0 ~ 2π periodically change, and the electric field vector end of the trajectory in the plane perpendicular to the direction of propagation projection is an ellipse, known as elliptical polarization. When the electric field vertical component and the horizontal component of the amplitude and phase has any value (two components are equal to the exception), can be obtained elliptical polarization.

10, long-wave antenna, medium-wave antenna

Is working in the long-wave and medium-wave band of the transmitting antenna or receiving antenna collectively. Long and medium waves are propagated by ground waves and sky waves, and sky waves are continuously reflected in the ionosphere and between the earth. According to this propagation characteristics, long and medium wave antenna should be able to produce a vertical polarization of the wave. In the long and medium wave antenna, the application of a wide range of vertical, inverted L type, T type, umbrella type vertical grounding antenna. Long and medium wave antenna should have a good ground network. Long and medium wave antenna has many technical problems, such as small effective height, small radiation resistance, low efficiency, narrow passband, small directional coefficient, etc.. In order to solve these problems, the antenna structure is often very complex and very large.

11, short-wave antenna

Work in the short-wave band transmitting or receiving antenna, collectively known as short-wave antenna. Short-wave is mainly with the ionosphere reflection of the sky wave propagation, is one of the important means of modern long-range radio communication. Short-wave antenna form many, which is the most used symmetric antenna, the same phase level antenna, times the wave antenna, angle antenna, V-type antenna, diamond antenna, herringbone antenna, etc.. And long wave antenna comparison, short wave antenna effective height, radiation resistance, high efficiency, good directionality, high gain, passband width.

12, ultra-shortwave antenna

Work in the ultra-short wave band of the transmitting and receiving antenna called ultra-short wave antenna. Ultra-short wave mainly by space wave propagation. This antenna form a lot, which is the most used Yagi antenna, disk cone antenna, double cone antenna, "bat wing" TV transmitting antenna, etc..

13, microwave antenna

Work in the meter wave, sub-meter wave, centimeter wave, millimeter wave and other bands of transmitting or receiving antenna, collectively referred to as microwave antenna. Microwave mainly by space wave propagation, in order to increase the communication distance, antenna erected higher. In the microwave antenna, the wider application of parabolic antenna, horn parabolic antenna, horn antenna, lens antenna, slotted antenna, medium antenna, periscope antenna, etc.

14, directional antenna

Directional antenna is in a particular direction or a particular direction and the reception of electromagnetic waves are particularly strong, and in the other direction of the emission and reception of electromagnetic waves are zero or very small antenna. The purpose of using directional transmitting antenna is to increase the effective utilization of radiation power, increase confidentiality; the main purpose of using directional receiving antenna is to increase the anti-interference ability.

15, not directional antenna

In all directions of uniform radiation or receive electromagnetic wave antenna, called undirected antenna, such as small communication machine with the whip antenna.

16, broadband antenna

Directionality, impedance and polarization characteristics in a very wide band almost constant antenna, called wide-band antenna. Early broadband antenna has a diamond antenna, V-shaped antenna, times the wave antenna, disk cone antenna, etc., the new broadband antenna has a logarithmic period antenna.

17, tuned antenna

Only in a very narrow band antenna with predetermined direction, called tuned antenna or tuned directional antenna. Usually, the tuned antenna only in its tuning frequency near 5% of the band, the direction remains unchanged, and in other frequencies, directional changes are very strong, in order to cause damage to communications. Tuned antenna is not suitable for frequency change of short-wave communication. The same phase horizontal antenna, folded antenna, zigzag antenna, etc. are tuned antenna.

18, vertical antenna

Vertical antenna is the antenna placed vertically with the ground. It has symmetric and asymmetric two forms, and the latter is more widely used. Symmetric vertical antenna is often center-fed. Asymmetric vertical antenna is fed between the bottom of the antenna and the ground, its maximum radiation direction in the case of height less than 1/2 wavelength, concentrated in the ground direction, so adapted to broadcast. Asymmetric vertical antenna also called vertical grounding antenna.

19, inverted L antenna

In a single horizontal wire end connected to a vertical lead wire and the composition of the antenna. Because of its shape like the English letter L upside down, it is called inverted L-shaped antenna. The Russian letter of the word Γ is exactly the English letter L backwards. So called Γ antenna more convenient. It is a form of vertical grounding antenna. In order to improve the efficiency of the antenna, the horizontal part of it can be used in the same horizontal line of several wires, the radiation generated by this part can be ignored, the radiation is the vertical part.

Inverted L antenna is generally used for long-wave communication. Its advantage is simple structure, easy to set up; disadvantage is that it covers a large area, durability is poor.

20T, shape antenna

In the center of the horizontal wire, connected to a vertical lead line, the shape of the letter T, so called T-shaped antenna. It is the most common kind of vertical grounded antenna. Its horizontal part of the radiation can be ignored, the radiation is generated by the vertical part. In order to improve efficiency, the horizontal part can also be composed of multiple wires. T-shaped antenna has the same characteristics as the inverted L-shaped antenna. It is generally used for long-wave and medium-wave communication.

21, umbrella antenna

In the top of a single vertical wire, led in all directions down a few inclined conductors, so that the shape of the antenna like open umbrella, so called umbrella antenna. It is also a form of vertical grounding antenna. Its characteristics and use and inverted L-shaped, T-shaped antenna the same.

22, whip antenna

Whip antenna is a bendable vertical rod antenna, its length is generally 1/4 or 1/2 wavelength. Most of the whip antennas are used without ground line and ground network. Small whip antenna often use the small radio station metal shell for the ground network. Sometimes in order to increase the effective height of the whip antenna, can be added to the top of the whip antenna some small spoke blade or inductor in the middle of the whip antenna.

Whip antenna can be used for small communication machine, step talk machine, car radio, etc.

23, symmetric antenna

The two parts of equal length and the center is disconnected and connected to feed the wire, can be used as a transmitting and receiving antenna, so that the antenna is called symmetrical antenna. Because the antenna is sometimes called the oscillator, so the symmetric antenna is also called symmetric oscillator, or dipole antenna. The total length of half a wavelength of the symmetric oscillator, called half-wave oscillator, also called half-wave dipole antenna. It is the most basic unit antenna, also used most widely, many complex antennas are composed of it. Half wave oscillator structure is simple, feed convenient, in the close range communication application more.

24、Cage antenna

Is a kind of wide band weak directional antenna. It is a few wires surrounded by a hollow cylinder instead of a symmetric antenna in the single wire radiation body, because the radiation body is cage-shaped, so called cage antenna. Cage antenna working band wide, easy to tune. It is adapted to the close range of the trunk line communication.

25, angle antenna

Belong to a class of symmetric antenna, but its two arms are not arranged in a straight line, and 90 ° or 120 ° angle, so called angle antenna. This antenna is generally a horizontal device, its direction is not significant. In order to get a wide band characteristics, angle antenna double arm can also use cage structure, called angle cage antenna.

26, folded antenna

Bend the oscillator into a symmetric antenna parallel to each other called folded antenna. There are two-line folded antenna, three-line folded antenna and multi-line folded antenna several forms, bending, should make each line on the corresponding point of the current with the phase, from a distance, the whole antenna as a symmetric antenna. But folded antenna and symmetric antenna, radiation enhancement. Input impedance increases, easy to couple with the feed line. Folded antenna is a tuned antenna, working frequency is narrow. It is widely used in shortwave and ultra-shortwave band.

27, V-shaped antenna

Is composed of two wires at an angle to each other, the shape of the letter V like an antenna. Its terminal can be open circuit, can also be connected with resistance, the size of the resistance is equal to the characteristic impedance of the antenna. v-shaped antenna has a unidirectional, the maximum direction of emission in the direction of the vertical plane of the sub-angle line. Its disadvantage is low efficiency, large footprint.

28、Rhombus antenna

Is a broadband antenna. It is composed of a horizontal rhombus suspended in four pillars, rhombus of an acute angle connected to the feed line, another acute angle connected to a rhombus antenna characteristic impedance equal to the terminal resistance. In the direction of the terminal resistance in the vertical plane, with unidirectional.

The advantage of the rhombus antenna is high gain, directional, using a wide band, easy to set up and maintenance; disadvantage is a large footprint. After the deformation of the rhombus antenna, there are double rhombus antenna, back to teach the rhombus antenna and folded rhombus antenna three forms. Rhombic antenna is generally used for large and medium-sized short-wave receiving radio.

29, disk cone antenna

Is a kind of ultra-shortwave antenna. The top is a disk (i.e., radiation body), by the heart of the coaxial line feed, the following is a cone, connected to the outer conductor of the coaxial line. The role of the cone is similar to the infinite ground, change the tilt angle of the cone, it can change the maximum radiation direction of the antenna. It has an extremely wide frequency band.

30, fishbone antenna

Fishbone antenna is also called side shot antenna, is a special shortwave receiving antenna. By in two collection line every certain distance connected to a symmetrical oscillator, these symmetrical oscillators are through a very small capacitor to the collection line. In the end of the collection line, that is, the end of the direction of communication, connected to a resistor with the collection line characteristic impedance equal, the other end is through the feed line to the receiver. Compared with the diamond antenna, the advantage of the herringbone antenna is a small flap (that is, the main flap direction receiving ability is strong, in other directions receiving weaker), the antenna between the mutual influence of small, small area; disadvantage is low efficiency, installation and use are more complex.

31、Yagi antenna

Also called leading antenna. It has a few metal rods, one of them is a radiator, a longer radiator for the reflector, the front of a number of shorter is the introducer. The radiator is usually folded half-wave oscillator. The antenna maximum radiation direction and the direction of the pilot pointing the same. Yagi antenna has the advantage of simple structure, light and strong, easy to feed; disadvantage of narrow frequency band, poor anti-interference. In the ultra-short wave communication and radar applications.

32, sector antenna

It has metal plate type and metal wire type two forms. Among them, is the fan-shaped metal plate type, is the fan-shaped metal wire type. This kind of antenna due to increase the antenna cross-sectional area, so widen the antenna frequency band. Wire type fan antenna can be used three, four or five metal wire. Sector antenna for ultra-shortwave reception.

33, biconical antenna

Biconical antenna consists of two cone top opposite cone, in the cone top feed. Cone can be used metal surface, metal wire or metal network composition. Just like the cage antenna, due to the antenna cross-sectional area increases, the antenna frequency band is also widened. Biconical antenna is mainly used for ultra-shortwave reception.

34, parabolic antenna

Parabolic antenna is a directional microwave antenna, by the parabolic reflector and radiator, the radiator is installed in the focus of the parabolic reflector or focal axis. The electromagnetic wave from the radiator is reflected by the parabolic surface, forming a highly directional beam.

Parabolic reflector made of metal with good conductivity, there are four main ways: rotating paraboloid, column paraboloid, cut-off rotating paraboloid and elliptical edge paraboloid, the most commonly used is the rotating paraboloid and column paraboloid. The radiator generally uses half wave oscillator, open waveguide, slotted waveguide and so on.  

The parabolic antenna has the advantages of simple structure, strong directionality and wide working band. The disadvantage is: because the radiator is located in the electric field of the parabolic reflector, so the reflector on the radiator's reaction is large, the antenna and the feed line is difficult to get a good match; back radiation is larger; protection is poor; high production accuracy. In microwave relay communication, tropospheric scattering communication, radar and television in the widely used this antenna.

35, horn parabolic antenna

Horn parabolic antenna is composed of two parts, horn and parabolic surface. The parabolic surface is covered on the horn, and the apex of the horn is located on the focal point of the parabolic surface. The horn is a radiator, which radiates electromagnetic waves to the paraboloid, and the electromagnetic waves are reflected by the paraboloid and focused into a narrow beam to be emitted.   The advantages of the horn paraboloidal antenna are

Reflector on the radiator has no counter effect, radiator on the reflected waves have no blocking effect, antenna and feeder match better; back radiation is small; protection is high; working band is very wide; structure is simple. Horn parabolic antenna is widely used in trunk line relay communication.

36, horn antenna

Also called horn antenna. It is by a uniform waveguide and a section of slowly increasing horn waveguide composition. Horn antenna has three forms: fan-shaped horn antenna, horn cone horn antenna and conical horn antenna.

Horn antenna is one of the most commonly used microwave antenna, generally used as a radiator. Its advantage is a wide working band; disadvantage is larger, and on the same caliber, it is not as sharp as the direction of the parabolic antenna.

37, horn lens antenna

By the horn and installed in the horn caliber lens, so called the horn lens antenna. The principle of the lens see lens antenna, this antenna has a fairly wide band, and higher protection than the parabolic antenna, it is used widely in the number of channels microwave trunk line communication.

38、Lens antenna

In the centimeter band, many optical principles can be used in the antenna. In optics, the use of lenses can make the point light source placed on the focal point of the lens radiation out of the spherical wave, through the lens refraction into a plane wave. Lens antenna is the use of this principle is made. It consists of a lens and put on the focus of the lens radiator. Lens antenna has medium deceleration lens antenna and metal acceleration lens antenna two kinds. The lens is made of low-loss high-frequency medium, thick in the middle and thin around. The spherical wave from the radiation source through the medium lens is decelerated. So the spherical wave in the middle part of the lens by the deceleration path is long, in the surrounding part by the deceleration path is short. Therefore, the spherical wave through the lens becomes a plane wave, that is, the radiation becomes directional. The lens is made of many metal plates of different lengths placed in parallel. The metal plate is perpendicular to the ground, the closer to the middle of the metal plate, the shorter. Electric waves in the parallel metal plate propagation is accelerated. The spherical wave from the radiation source through the metal lens, the closer the edge of the lens, the longer the path of acceleration, and in the middle, the path of acceleration is short. Therefore, after the metal lens spherical wave becomes a plane wave.  

Lens antenna has the following advantages:

1, the side flap and after the flap is small, so the directional map is better;

2, the manufacture of the lens is not high precision, so the manufacture is more convenient. The disadvantage is low efficiency, complex structure, expensive. Lens antenna is used in microwave relay communication.

39、slotted antenna

In a large metal plate to open a narrow slot or several, with coaxial line or waveguide feed, so that the antenna is called slotted antenna, also known as slit antenna. In order to get a one-way radiation, the back of the metal plate made of cavity, slotted directly by the waveguide feed. Slotted antenna structure is simple, no projection, so it is especially suitable for use in high-speed aircraft. Its disadvantage is the tuning difficulty.

40, medium antenna

The medium antenna is a low-loss high-frequency medium material (generally with polystyrene) made of round rod, it is fed by coaxial line or waveguide at one end. 2 is the extension of the inner conductor of the coaxial line, forming an oscillator to excite electromagnetic waves; 3 is the coaxial line; 4 is the metal sleeve. The role of the sleeve in addition to clamping the dielectric rod, more importantly, is to reflect the electromagnetic wave, thus ensuring that the electromagnetic wave is excited by the inner conductor of the coaxial line, and propagate to the free end of the dielectric rod.

The advantage of the medium antenna is small size, directional sharp; disadvantage is that the medium has loss, thus the efficiency is not high.

41, periscope antenna

In the microwave relay communication, the antenna is often placed in a very high bracket, therefore, to feed the antenna will have to use a very long feed line. The feed line is too long will produce many difficulties, such as complex structure, energy loss, due to the energy reflection at the feed line joints and cause distortion. In order to overcome these difficulties, a periscope antenna can be used, periscope antenna is placed on the ground by the lower mirror radiator and mounted on the bracket on the mirror reflector. The lower mirror radiator is generally parabolic antenna, the upper mirror reflector for the metal plate. The lower mirror radiator emits electromagnetic waves upward, after the metal plate reflected out.

The advantage of the periscope antenna is small energy loss, small distortion, high efficiency. Mainly used in the capacity of microwave relay communication.

42, spiral antenna

Is a kind of antenna with spiral shape. It is composed of metal spiral line with good conductivity, usually fed with coaxial line, the heart of the coaxial line and one end of the spiral line is connected, the outer conductor of the coaxial line is connected with the grounded metal network (or plate). The radiation direction of the spiral antenna is related to the circumference of the spiral line.

When the circumference of the spiral line is much smaller than a wavelength, the strongest direction of radiation perpendicular to the spiral axis; when the circumference of the spiral line for a wavelength of the order of magnitude, the strongest radiation appears in the direction of the spiral spiral axis.

43、Antenna tuner

Connect the transmitter and the antenna of an impedance matching network, called the antenna tuner. Antenna input impedance with frequency and a large change, and the transmitter output impedance is a certain, if the transmitter and antenna directly connected, when the transmitter frequency change, the transmitter and antenna impedance between the mismatch, it will reduce the radiation power. Using antenna tuner, it can make the impedance match between transmitter and antenna, so that the antenna has the maximum radiated power at any frequency. Antenna tuner is widely used in ground, vehicle, naval and aviation shortwave radio.

44、Log-periodic antenna

It is a kind of broadband antenna, or a frequency independent antenna. Among them, is a simple log periodic antenna, its dipole length and spacing in accordance with the following relationship:

τ dipole by a uniform two-wire transmission line to feed, the transmission line in the adjacent dipole to swap positions between. This antenna has a characteristic: where the characteristics that have on f frequency will be repeated on all frequencies given by τⁿf, where n is an integer. These frequencies are drawn on a logarithmic scale are equally spaced, and the period is equal to the logarithm of τ. The name of the logarithmic periodic antenna is derived from this. Logarithmic period antenna is only periodically repeat the radiation map and impedance characteristics. But such a structure of the antenna, if τ is not much less than 1, then its characteristics in a period of change is very small, and therefore is basically independent of frequency. Logarithmic period antenna has many kinds, logarithmic period dipole antenna and monopole antenna, logarithmic period resonant V antenna, logarithmic period spiral antenna and other forms, the most common is logarithmic period dipole antenna. These antennas are widely used in shortwave and shortwave above the band.