romikgosai/squad_modified_2 huggingface dataset:
One example of omnidirectional antennas is the very common vertical antenna or whip antenna consisting of a metal rod (often, but not always, a quarter of a wavelength long). A dipole antenna is similar but consists of two such conductors extending in opposite directions, with a total length that is often, but not always, a half of a wavelength long. Dipoles are typically oriented horizontally in which case they are weakly directional: signals are reasonably well radiated toward or received from all directions with the exception of the direction along the conductor itself; this region is called the antenna blind cone or null.

Q1: What is the main element of an omnidirectional antenna?
A1: metal rod
Q2: What type of antenna would most likely be a half a wavelength long?
A2: dipole
Q3: In which direction would you expect to find a dipole?
A3: horizontally
Q4: What is meant by the area where signals cannot be accepted well along the conductor?
A4: null
Both the vertical and dipole antennas are simple in construction and relatively inexpensive. The dipole antenna, which is the basis for most antenna designs, is a balanced component, with equal but opposite voltages and currents applied at its two terminals through a balanced transmission line (or to a coaxial transmission line through a so-called balun). The vertical antenna, on the other hand, is a monopole antenna. It is typically connected to the inner conductor of a coaxial transmission line (or a matching network); the shield of the transmission line is connected to ground. In this way, the ground (or any large conductive surface) plays the role of the second conductor of a dipole, thereby forming a complete circuit. Since monopole antennas rely on a conductive ground, a so-called grounding structure may be employed to provide a better ground contact to the earth or which itself acts as a ground plane to perform that function regardless of (or in absence of) an actual contact with the earth.

Q1: Are basic antennas expensive?
A1: relatively inexpensive
Q2: What is the foundation most often used when creating new antenna models?
A2: dipole antenna
Q3: What category do vertical antennas fall under?
A3: monopole antenna
Q4: What is used to close the circuit of a dipole antenna?
A4: large conductive surface
Antennas more complex than the dipole or vertical designs are usually intended to increase the directivity and consequently the gain of the antenna. This can be accomplished in many different ways leading to a plethora of antenna designs. The vast majority of designs are fed with a balanced line (unlike a monopole antenna) and are based on the dipole antenna with additional components (or elements) which increase its directionality. Antenna "gain" in this instance describes the concentration of radiated power into a particular solid angle of space, as opposed to the spherically uniform radiation of the ideal radiator. The increased power in the desired direction is at the expense of that in the undesired directions. Power is conserved, and there is no net power increase over that delivered from the power source (the transmitter.)

Q1: What are different designs aimed at increasing?
A1: gain of the antenna
Q2: What is different from a monopole antenna with most other antenna types?
A2: balanced line
Q3: Gain when referring to an antenna refers to what about radiated power?
A3: concentration
Q4: Where is the power that is distributed originating from?
A4: the transmitter
For instance, a phased array consists of two or more simple antennas which are connected together through an electrical network. This often involves a number of parallel dipole antennas with a certain spacing. Depending on the relative phase introduced by the network, the same combination of dipole antennas can operate as a "broadside array" (directional normal to a line connecting the elements) or as an "end-fire array" (directional along the line connecting the elements). Antenna arrays may employ any basic (omnidirectional or weakly directional) antenna type, such as dipole, loop or slot antennas. These elements are often identical.

Q1: How many antenna would make up a phased array?
A1: two or more
Q2: What determines if the antenna creates a broadside array or an end fire array?
A2: relative phase
Q3: What are the two standard antenna types?
A3: omnidirectional or weakly directional
Q4: How are antennas oriented when arranged with specific spacing?
A4: parallel
However a log-periodic dipole array consists of a number of dipole elements of different lengths in order to obtain a somewhat directional antenna having an extremely wide bandwidth: these are frequently used for television reception in fringe areas. The dipole antennas composing it are all considered "active elements" since they are all electrically connected together (and to the transmission line). On the other hand, a superficially similar dipole array, the Yagi-Uda Antenna (or simply "Yagi"), has only one dipole element with an electrical connection; the other so-called parasitic elements interact with the electromagnetic field in order to realize a fairly directional antenna but one which is limited to a rather narrow bandwidth. The Yagi antenna has similar looking parasitic dipole elements but which act differently due to their somewhat different lengths. There may be a number of so-called "directors" in front of the active element in the direction of propagation, and usually a single (but possibly more) "reflector" on the opposite side of the active element.

Q1: What type of antenna formation is made up of multiple dipole elements of varying lengths?
A1: log-periodic dipole array
Q2: What is the benefit of this formation type?
A2: extremely wide bandwidth
Q3: What is a variation of this antenna type?
A3: Yagi-Uda Antenna
Q4: What is the main application of these set ups?
A4: television reception
At low frequencies (such as AM broadcast), arrays of vertical towers are used to achieve directionality  and they will occupy large areas of land. For reception, a long Beverage antenna can have significant directivity. For non directional portable use, a short vertical antenna or small loop antenna works well, with the main design challenge being that of impedance matching. With a vertical antenna a loading coil at the base of the antenna may be employed to cancel the reactive component of impedance; small loop antennas are tuned with parallel capacitors for this purpose.

Q1: For radio broadcast that one would hear in their car what type of towers are used?
A1: vertical
Q2: If one wished to take an antenna to different locations, which type would be best?
A2: short vertical antenna
Q3: Why is this specific antenna type used?
A3: achieve directionality
Q4: What is a problem one might encounter when using a portable antenna?
A4: impedance matching
An antenna lead-in is the transmission line (or feed line) which connects the antenna to a transmitter or receiver. The antenna feed may refer to all components connecting the antenna to the transmitter or receiver, such as an impedance matching network in addition to the transmission line. In a so-called aperture antenna, such as a horn or parabolic dish, the "feed" may also refer to a basic antenna inside the entire system (normally at the focus of the parabolic dish or at the throat of a horn) which could be considered the one active element in that antenna system. A microwave antenna may also be fed directly from a waveguide in place of a (conductive) transmission line.

Q1: What is mainly responsible for the connection of the antenna to its end destinations?
A1: antenna lead-in
Q2: What is the group of elements used to join the elements of an antenna?
A2: antenna feed
Q3: What are the type of antennas used with satellite television called?
A3: aperture antenna
Q4: What can be used in place of  a standard transmission line?
A4: microwave antenna
Monopole antennas consist of a single radiating element such as a metal rod, often mounted over a conducting surface, a ground plane. One side of the feedline from the receiver or transmitter is connected to the rod, and the other side to the ground plane, which may be the Earth. The most common form is the quarter-wave monopole which is one-quarter of a wavelength long and has a gain of 5.12 dBi when mounted over a ground plane. Monopoles have an omnidirectional radiation pattern, so they are used for broad coverage of an area, and have vertical polarization. The ground waves used for broadcasting at low frequencies must be vertically polarized, so large vertical monopole antennas are used for broadcasting in the MF, LF, and VLF bands. Small monopoles are used as nondirectional antennas on portable radios in the HF, VHF, and UHF bands.

Q1: Monopole antennas consist of what element?
A1: metal rod
Q2: What are small monopoles used as?
A2: nondirectional antennas
Q3: What the most common form?
A3: quarter-wave monopole
Q4: What has vertical polarization?
A4: Monopoles
A necessary condition for the aforementioned reciprocity property is that the materials in the antenna and transmission medium are linear and reciprocal. Reciprocal (or bilateral) means that the material has the same response to an electric current or magnetic field in one direction, as it has to the field or current in the opposite direction. Most materials used in antennas meet these conditions, but some microwave antennas use high-tech components such as isolators and circulators, made of nonreciprocal materials such as ferrite. These can be used to give the antenna a different behavior on receiving than it has on transmitting, which can be useful in applications like radar.

Q1: What must be true of the antenna and transmission medium for the repiprocity rule to apply ?
A1: linear and reciprocal
Q2: What is one material that does not have this quality?
A2: ferrite
Q3: How can the lack of this quality be used in an everyday way?
A3: radar
Q4: What is called when the direction of the elctrical current does not make a difference to the current?
A4: Reciprocal
Antennas are characterized by a number of performance measures which a user would be concerned with in selecting or designing an antenna for a particular application. Chief among these relate to the directional characteristics (as depicted in the antenna's radiation pattern) and the resulting gain. Even in omnidirectional (or weakly directional) antennas, the gain can often be increased by concentrating more of its power in the horizontal directions, sacrificing power radiated toward the sky and ground. The antenna's power gain (or simply "gain") also takes into account the antenna's efficiency, and is often the primary figure of merit.

Q1: How could one deide what type of antenna is nedded for a project?
A1: performance measures
Q2: What would most likely be the main concern in making this decision?
A2: directional characteristics
Q3: How would you distribute power to allow for a greater gain?
A3: horizontal directions
Q4: What is often the most imprtant crediting factor of antennas?
A4: efficiency
Resonant antennas are expected to be used around a particular resonant frequency; an antenna must therefore be built or ordered to match the frequency range of the intended application. A particular antenna design will present a particular feedpoint impedance. While this may affect the choice of an antenna, an antenna's impedance can also be adapted to the desired impedance level of a system using a matching network while maintaining the other characteristics (except for a possible loss of efficiency).

Q1: Which antenna type would be best for a project requiring a specific frequency?
A1: Resonant antennas
Q2: How could an antenna be made to coordinate with the needed frequency?
A2: built or ordered
Q3: What factor would result in a desired feedback independence?
A3: particular antenna design
Q4: If you were unable to choose the antenna you wanted how could you still achieve this result?
A4: matching network
An antenna transmits and receives radio waves with a particular polarization which can be reoriented by tilting the axis of the antenna in many (but not all) cases. The physical size of an antenna is often a practical issue, particularly at lower frequencies (longer wavelengths). Highly directional antennas need to be significantly larger than the wavelength. Resonant antennas usually use a linear conductor (or element), or pair of such elements, each of which is about a quarter of the wavelength in length (an odd multiple of quarter wavelengths will also be resonant). Antennas that are required to be small compared to the wavelength sacrifice efficiency and cannot be very directional. Fortunately at higher frequencies (UHF, microwaves) trading off performance to obtain a smaller physical size is usually not required.

Q1: What is the essential difference in radio waves transmitted by an antenna?
A1: polarization
Q2: How can this be adjusted more easily than changing antenna types?
A2: tilting the axis
Q3: When might the size of an antenna cause an issue?
A3: at lower frequencies
Q4: What size antenna would not be good when the antenna needs to be directional?
A4: small
Q5: There is a relationship between the size of the antenna and the size of the wavelength with what antenna type?
A5: Highly directional
The majority of antenna designs are based on the resonance principle. This relies on the behaviour of moving electrons, which reflect off surfaces where the dielectric constant changes, in a fashion similar to the way light reflects when optical properties change. In these designs, the reflective surface is created by the end of a conductor, normally a thin metal wire or rod, which in the simplest case has a feed point at one end where it is connected to a transmission line. The conductor, or element, is aligned with the electrical field of the desired signal, normally meaning it is perpendicular to the line from the antenna to the source (or receiver in the case of a broadcast antenna).

Q1: What particle's migration does the resonance principle rely on?
A1: electrons
Q2: What is the basis for the way most antennas are developed?
A2: resonance principle
Q3: What type of surface is formed by the tip of a conductor?
A3: reflective
Q4: How would you place the conductor in relation to the signal you wished to obtain?
A4: perpendicular
The radio signal's electrical component induces a voltage in the conductor. This causes an electrical current to begin flowing in the direction of the signal's instantaneous field. When the resulting current reaches the end of the conductor, it reflects, which is equivalent to a 180 degree change in phase. If the conductor is 1⁄4 of a wavelength long, current from the feed point will undergo 90 degree phase change by the time it reaches the end of the conductor, reflect through 180 degrees, and then another 90 degrees as it travels back. That means it has undergone a total 360 degree phase change, returning it to the original signal. The current in the element thus adds to the current being created from the source at that instant. This process creates a standing wave in the conductor, with the maximum current at the feed.

Q1: What part of the radio signal creates voltage?
A1: electrical component
Q2: What would the electric current always gravitate to?
A2: instantaneous field
Q3: What is the outcome when a curren is reflected>
A3: 180 degree change in phase
Q4: What amount of phase change would return a signal to its originial state?
A4: 360 degree
The ordinary half-wave dipole is probably the most widely used antenna design. This consists of two 1⁄4-wavelength elements arranged end-to-end, and lying along essentially the same axis (or collinear), each feeding one side of a two-conductor transmission wire. The physical arrangement of the two elements places them 180 degrees out of phase, which means that at any given instant one of the elements is driving current into the transmission line while the other is pulling it out. The monopole antenna is essentially one half of the half-wave dipole, a single 1⁄4-wavelength element with the other side connected to ground or an equivalent ground plane (or counterpoise). Monopoles, which are one-half the size of a dipole, are common for long-wavelength radio signals where a dipole would be impractically large. Another common design is the folded dipole, which is essentially two dipoles placed side-by-side and connected at their ends to make a single one-wavelength antenna.

Q1: What is the most popular antenna type?
A1: half-wave dipole
Q2: What is the current usually beng put into it or pulled out of?
A2: transmission line
Q3: Elements in a half wave dipole and on an identical axis are said to be what?
A3: collinear
Q4: What antenna type is a portion of the half wave dipole?
A4: Monopoles
Q5: What popular type combines more that one antenna?
A5: folded dipole
The standing wave forms with this desired pattern at the design frequency, f0, and antennas are normally designed to be this size. However, feeding that element with 3f0 (whose wavelength is 1⁄3 that of f0) will also lead to a standing wave pattern. Thus, an antenna element is also resonant when its length is 3⁄4 of a wavelength. This is true for all odd multiples of 1⁄4 wavelength. This allows some flexibility of design in terms of antenna lengths and feed points. Antennas used in such a fashion are known to be harmonically operated.

Q1: What frequency are antennas normally designed to be?
A1: f0
Q2: What can be added to f0 to create a standing wave pattern?
A2: 3f0
Q3: What multiple is essential for wavelengths?
A3: 1⁄4
Q4: How are waves which are used in the ways discussed controlled?
A4: harmonically
The quarter-wave elements imitate a series-resonant electrical element due to the standing wave present along the conductor. At the resonant frequency, the standing wave has a current peak and voltage node (minimum) at the feed. In electrical terms, this means the element has minimum reactance, generating the maximum current for minimum voltage. This is the ideal situation, because it produces the maximum output for the minimum input, producing the highest possible efficiency. Contrary to an ideal (lossless) series-resonant circuit, a finite resistance remains (corresponding to the relatively small voltage at the feed-point) due to the antenna's radiation resistance as well as any actual electrical losses.

Q1: How do quarter wave elements act in relation to a series relevant electrical element?
A1: imitate
Q2: What frequency develops a current peak?
A2: resonant frequency
Q3: How would you describe a current that has maximum efficiency?
A3: minimum reactance
Q4: What could be the best possible output versus input ratio?
A4: lossless
It is possible to use the impedance matching concepts to construct vertical antennas substantially shorter than the 1⁄4 wavelength at which the antenna is resonant. By adding an inductance in series with the antenna, a so-called loading coil, the capacitive reactance of this antenna can be cancelled leaving a pure resistance which can then be matched to the transmission line. Sometimes the resulting resonant frequency of such a system (antenna plus matching network) is described using the construct of electrical length and the use of a shorter antenna at a lower frequency than its resonant frequency is termed electrical lengthening.

Q1: For use with more than one channel changes are made to increase what property?
A1: impedance matching
Q2: What could be coupled with an antenna to form pure resistance?
A2: inductance
Q3: What element would this pure resistance be coupled with?
A3: transmission line
Q4: What phrase describes the process of purposely using a lower standing antenna at a less than peak frequency?
A4: electrical lengthening
The end result is that the resonant antenna will efficiently feed a signal into the transmission line only when the source signal's frequency is close to that of the design frequency of the antenna, or one of the resonant multiples. This makes resonant antenna designs inherently narrowband, and they are most commonly used with a single target signal. They are particularly common on radar systems, where the same antenna is used for both broadcast and reception, or for radio and television broadcasts, where the antenna is working with a single frequency. They are less commonly used for reception where multiple channels are present, in which case additional modifications are used to increase the bandwidth, or entirely different antenna designs are used.

Q1:  If your were unable to match the source frequency with the design frequency of the antenna what could you use?
A1: resonant multiples
Q2: What is the most common application of resonant antennas?
A2: single target signal
Q3: What antenna setup type is generally used for TV viewing?
A3: resonant
Q4: For use with more than one channel changes are made to increase what property?
A4: bandwidth
The amount of signal received from a distant transmission source is essentially geometric in nature due to the inverse square law, and this leads to the concept of effective area. This measures the performance of an antenna by comparing the amount of power it generates to the amount of power in the original signal, measured in terms of the signal's power density in Watts per square metre. A half-wave dipole has an effective area of 0.13 2. If more performance is needed, one cannot simply make the antenna larger. Although this would intercept more energy from the signal, due to the considerations above, it would decrease the output significantly due to it moving away from the resonant length. In roles where higher performance is needed, designers often use multiple elements combined together.

Q1: What accounts for the geometry involved in the use of an antenna?
A1: inverse square law
Q2:  How is the compactness of the signal measured?
A2: Watts per square metre
Q3: What type of project would call for more than one element used together?
A3: higher performance
Returning to the basic concept of current flows in a conductor, consider what happens if a half-wave dipole is not connected to a feed point, but instead shorted out. Electrically this forms a single 1⁄2-wavelength element. But the overall current pattern is the same; the current will be zero at the two ends, and reach a maximum in the center. Thus signals near the design frequency will continue to create a standing wave pattern. Any varying electrical current, like the standing wave in the element, will radiate a signal. In this case, aside from resistive losses in the element, the rebroadcast signal will be significantly similar to the original signal in both magnitude and shape. If this element is placed so its signal reaches the main dipole in-phase, it will reinforce the original signal, and increase the current in the dipole. Elements used in this way are known as passive elements.

Q1: What is a half wave dipole need to be coupled with in most instances?
A1: feed point
Q2: What part of the current is usually strongest?
A2: center
Q3: What does this result in?
A3: standing wave pattern
Q4: Element used to provide support to the original signal are called?
A4: passive elements