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How loop antenna and dipole antenna can be used interchangeably?
Wiki User
∙ 9y ago
A full-wave loop antenna can be interchanged with a folded dipole without much difference. The input impedance is similar and the only difference is in the directivity: a full wave loop radiates along the axis of the loop, while a vertical folded dipole is omnidirectional.
Wiki User
∙ 9y ago
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When a vertical dipole antenna is used in conjunction with a loop antenna for direction finding then the field pattern obtained will be?
Loop antenna generate the same field as electrical dipole, but E and H are exchanged (a proof can be obtained this way: you align an electrical dipole with an axis, say z, and a loop antenna with z - you have to define surface orientation - then you apply duality theorem, calculate far field and you got it). For instance, in spherical coordinates (r,phi,theta) you have el. dipole {Etheta,Hphi} loop ant. {Ephi,Htheta} So, you can superpose the two fields and see that you have gained polarization independency (if an electrical dipole is aligned with z-axis and has its gap at z=0, it will receive very well Etheta, not at all Ephi (plane z=0), if you put a loop antenna "around" electrical dipole - like a ring around dipole's gap, lying on z=0 plane - it will receive very well Ephi (plane z=0) ). This is the way to make triaxial sensor, which have to be polarization independent.
What is the operational frequency of half wave dipole antenna?
Its resonant frequency is where its length is half a wavelength, so for 100 MHz the wavelength is 3 metres and a 1.5-metre long dipole is resonant. A dipole antenna can be used for many applications within a band of 10-20% around the resonant frequency.
Why was before used the 300 ohm transmission line?
The impedance of a centre fed dipole at resonance is about 73 ohms. The feed impedance of a folded dipole is four times that, 292 ohms. The feedpoint is of course balanced in both cases, thus 300 ohm balanced line is an excellent match for the folded dipole active element of a commercial TV antenna.
What is an antenna?
In Electomagnetics, Radio, Electronics, etc.:An antenna is a structure that couples energy between a circuit (radio, cell phone, etc.) and free space. The plural is antennas.In Biology, Zoology, etc.:An antenna is an organ used to sense the surroundings. The plural is antennae.
What is negative feedback of a closed loop system?
Negative feedback is a feedback where it is used in negative side in a closed loop system.Such as a inverting side feedback in op-amp.
When a vertical dipole antenna is used in conjunction with a loop antenna for direction finding then the field pattern obtained will be?
Loop antenna generate the same field as electrical dipole, but E and H are exchanged (a proof can be obtained this way: you align an electrical dipole with an axis, say z, and a loop antenna with z - you have to define surface orientation - then you apply duality theorem, calculate far field and you got it). For instance, in spherical coordinates (r,phi,theta) you have el. dipole {Etheta,Hphi} loop ant. {Ephi,Htheta} So, you can superpose the two fields and see that you have gained polarization independency (if an electrical dipole is aligned with z-axis and has its gap at z=0, it will receive very well Etheta, not at all Ephi (plane z=0), if you put a loop antenna "around" electrical dipole - like a ring around dipole's gap, lying on z=0 plane - it will receive very well Ephi (plane z=0) ). This is the way to make triaxial sensor, which have to be polarization independent.
Why dipole antenna not used for high frequency?
Depends on what you mean by high frequency. The rabbit ears antenna used in broadcast TV is a dipole and is used for VHF.
The type of antenna used for the television broadcasting?
Dipole
How does yagi-uda antenna differ from a folded dipole a loop antenna and a helical antenna?
Wow, your question on how a yagi-uda differs from a folded dipole, a loop antenna, and a helical antenna relates very much to how does a lawn mower engine relate to a V-8. The principals in all the antennas remains much the same. So I will deal with them in the order asked. The Yagi in its simplest form consists of 3 elements. The center element is the driven element and is essentially a dipole. Behind it is a slightly larger element called a reflector which does just that, it reflects signals to and from the dipole and in front there is the smaller director which helps focus energy. This is a directional antenna with gain. The folded dipole goes back to the basic dipole except it has makes a full loop. They are just as about as long as regular dipoles. With the loop of wire out there, they tend to have a wider band width than regular dipoles - but are not as tolerant of being used at even multiples of their cut frequency as the wires tend to cancel out each other. Oh, btw, yagi's have been made using folded dipoles. You must use ladder line or a 4:1 balun on folded dipoles, with perhaps the exception of the terminated folded dipole which has a resistor where the two elements of the dipole come together. The loop antenna? Which loop? I assume you are talking the traditional loop and not the magnetic loop. The full loop is normally computed to be 1005/frequency=feet. While you could take the time to tune the antenna, it might just be easier to put in a balun and an antenna tuner. The main advantage of a loop over the previous reviewed antennas is that it does fairly well even though fairly close to the ground where the previous 2 antennas should be at least 1/2 a wave length up for good performance. Helical antennas are generally good for just one band. In fact, due to the loading they cause they are best if used on a single frequency as their feed line requires them to be provided the connecting feed the is the electrical equivalent of a 1/2 wave at that frequency of operation. This may work well at VHF and above as an entire band can be tuned satisfactory, but in HF it would limit you to a very small segment of the band. Helical antennas definitely are the lawn mower engines of the antenna world. Look up antenna elmer on your favorite search engine. You have entered into a world where there is still a lot homework left to be done.
How does a loop antenna work?
There are two types of loop antenna used in radio, small and large. It is a loop of wire usually circular or square with the circuit (transmitter or receiver) connected at the two adjacent open ends. A large loop is one wavelength in circumference and radiates a wave along the axis of the loop. It can also be thought of as a folded half-wave dipole. A small loop also known as a magnetic loop is one tenth of a wavelength or less in circumference and radiates in the plane of the loop. Used as a receiver, a small loop gives an output signal voltage proportional to the magnetic component of the arriving radio wave. Small loops for receiving can be made from a coil of wire on a ferrite rod, and this type of loop is also called a loopstick antenna. Intermediate-sized loops have a rather unpredictable pattern so tend not be used.
What is the operational frequency of half wave dipole antenna?
Its resonant frequency is where its length is half a wavelength, so for 100 MHz the wavelength is 3 metres and a 1.5-metre long dipole is resonant. A dipole antenna can be used for many applications within a band of 10-20% around the resonant frequency.
What type of antenna used in rfid?
All types... depending on frequency and application. Lower frequency RFID's are typically near field and use inductive antenna designs, higher frequency ones use far-field designs. Low frequency RFID's like the TIRIS pet ID's use coils of wound wire. HF type RFID's like MiFARE use simple planar loop antenna designs. Most VHF RFID's use dipole and modified dipole designs with reflector elements. UHF and microwave RFID's frequently use patch and slot antenna designs.
What are the advantage of trap dipole antenna?
A dipole antenna, is a radio antenna that can be made of a simple wire, with a center-fed driven element. It consists of two metal conductors of rod or wire, oriented parallel and collinear with each other (in line with each other), with a small space between them. The radio frequency voltage is applied to the antenna at the center, between the two conductors. These antennas are the simplest practical antennas from a theoretical point of view. They are used alone as antennas, notably in traditional "rabbit ears" television antennas, and as the driven element in many other types of antennas, such as the Yagi. Dipole antennas were invented by German physicist Heinrich Hertz around 1886 in his pioneering experiments with radio waves.
What did Andrew alford invent?
Andrew Alford is known for his work in developing the Alford loop antenna, a type of radio antenna. It is commonly used in shortwave radio receivers for its compact and efficient design.
Why was before used the 300 ohm transmission line?
The impedance of a centre fed dipole at resonance is about 73 ohms. The feed impedance of a folded dipole is four times that, 292 ohms. The feedpoint is of course balanced in both cases, thus 300 ohm balanced line is an excellent match for the folded dipole active element of a commercial TV antenna.
Can Apostrophes and quotation marks can be used interchangeably?
Apostrophes and quotation marks can be used interchangeably.
Why Directional antenna are not useful for mobile phones?
Answer: No. Previous generations of mobile phones used the dipole antenna. (Some protruded, others were retractable.) A mobile phone must work in any orientation, so the antenna must be omnidirectional.
