id stringlengths 24 24 | question stringlengths 1 270 | answer stringlengths 1 239 | documents listlengths 1 1 |
|---|---|---|---|
57301dc304bcaa1900d771b5 | What equation an determine an antennas effectiveness? | Rr / (Rr + Rloss) | [
"Antenna_(radio)\n\nHowever loss resistance will generally affect the feedpoint impedance, adding to its resistive (real) component. That resistance will consist of the sum of the radiation resistance Rr and the loss resistance Rloss. If an rms current I is delivered to the terminals of an antenna, then a power of ... |
57301dc304bcaa1900d771b6 | What is the single factor that can be precisely measured? | total resistance | [
"Antenna_(radio)\n\nHowever loss resistance will generally affect the feedpoint impedance, adding to its resistive (real) component. That resistance will consist of the sum of the radiation resistance Rr and the loss resistance Rloss. If an rms current I is delivered to the terminals of an antenna, then a power of ... |
57301ea7947a6a140053d13a | In what type of programs would low efficiency antennas not make a difference in effectiveness? | receiving | [
"Antenna_(radio)\n\nAccording to reciprocity, the efficiency of an antenna used as a receiving antenna is identical to the efficiency as defined above. The power that an antenna will deliver to a receiver (with a proper impedance match) is reduced by the same amount. In some receiving applications, the very ineffic... |
57301ea7947a6a140053d13b | At lesser frequencies what can account for incorrect assumptions about efficiency? | man-made noise | [
"Antenna_(radio)\n\nAccording to reciprocity, the efficiency of an antenna used as a receiving antenna is identical to the efficiency as defined above. The power that an antenna will deliver to a receiver (with a proper impedance match) is reduced by the same amount. In some receiving applications, the very ineffic... |
57301ea7947a6a140053d13c | What is the median level for measuring atmospheric noise? | thermal noise floor | [
"Antenna_(radio)\n\nAccording to reciprocity, the efficiency of an antenna used as a receiving antenna is identical to the efficiency as defined above. The power that an antenna will deliver to a receiver (with a proper impedance match) is reduced by the same amount. In some receiving applications, the very ineffic... |
57301ea7947a6a140053d13d | What is SNR? | signal to noise ratio | [
"Antenna_(radio)\n\nAccording to reciprocity, the efficiency of an antenna used as a receiving antenna is identical to the efficiency as defined above. The power that an antenna will deliver to a receiver (with a proper impedance match) is reduced by the same amount. In some receiving applications, the very ineffic... |
573021e4a23a5019007fce0b | What else is also known as power gain? | antenna gain | [
"Antenna_(radio)\n\nThe definition of antenna gain or power gain already includes the effect of the antenna's efficiency. Therefore, if one is trying to radiate a signal toward a receiver using a transmitter of a given power, one need only compare the gain of various antennas rather than considering the efficiency ... |
573021e4a23a5019007fce0c | What is used to signal toward a reciever? | transmitter | [
"Antenna_(radio)\n\nThe definition of antenna gain or power gain already includes the effect of the antenna's efficiency. Therefore, if one is trying to radiate a signal toward a receiver using a transmitter of a given power, one need only compare the gain of various antennas rather than considering the efficiency ... |
573021e4a23a5019007fce0d | Which gain does not iclude the effect of an antenna? | directive gain | [
"Antenna_(radio)\n\nThe definition of antenna gain or power gain already includes the effect of the antenna's efficiency. Therefore, if one is trying to radiate a signal toward a receiver using a transmitter of a given power, one need only compare the gain of various antennas rather than considering the efficiency ... |
573021e4a23a5019007fce0e | Wats divided by the antennas efficiency? | published gain | [
"Antenna_(radio)\n\nThe definition of antenna gain or power gain already includes the effect of the antenna's efficiency. Therefore, if one is trying to radiate a signal toward a receiver using a transmitter of a given power, one need only compare the gain of various antennas rather than considering the efficiency ... |
57302439a23a5019007fce37 | Small and minimal frequency antennas are know to be what? | inefficient | [
"Antenna_(radio)\n\nThis is fortunate, since antennas at lower frequencies which are not rather large (a good fraction of a wavelength in size) are inevitably inefficient (due to the small radiation resistance Rr of small antennas). Most AM broadcast radios (except for car radios) take advantage of this principle b... |
57302439a23a5019007fce38 | What is added to to increase ability for reception? | small loop antenna | [
"Antenna_(radio)\n\nThis is fortunate, since antennas at lower frequencies which are not rather large (a good fraction of a wavelength in size) are inevitably inefficient (due to the small radiation resistance Rr of small antennas). Most AM broadcast radios (except for car radios) take advantage of this principle b... |
57302439a23a5019007fce39 | How would this antenna rate in the greater scheme of things? | little effect | [
"Antenna_(radio)\n\nThis is fortunate, since antennas at lower frequencies which are not rather large (a good fraction of a wavelength in size) are inevitably inefficient (due to the small radiation resistance Rr of small antennas). Most AM broadcast radios (except for car radios) take advantage of this principle b... |
57302439a23a5019007fce3a | When talking about much larger network what effect can reduced antenna effectiveness have? | substantial cost | [
"Antenna_(radio)\n\nThis is fortunate, since antennas at lower frequencies which are not rather large (a good fraction of a wavelength in size) are inevitably inefficient (due to the small radiation resistance Rr of small antennas). Most AM broadcast radios (except for car radios) take advantage of this principle b... |
57302473947a6a140053d188 | What is another name for electric-field? | E-plane | [
"Antenna_(radio)\n\nThe polarization of an antenna refers to the orientation of the electric field (E-plane) of the radio wave with respect to the Earth's surface and is determined by the physical structure of the antenna and by its orientation; note that this designation is totally distinct from the antenna's dire... |
57302473947a6a140053d189 | How many polarizations will a antenna have when mounted vertically? | one | [
"Antenna_(radio)\n\nThe polarization of an antenna refers to the orientation of the electric field (E-plane) of the radio wave with respect to the Earth's surface and is determined by the physical structure of the antenna and by its orientation; note that this designation is totally distinct from the antenna's dire... |
57302473947a6a140053d18a | Whats understood in reference of direction of an E-plane? | polarization | [
"Antenna_(radio)\n\nThe polarization of an antenna refers to the orientation of the electric field (E-plane) of the radio wave with respect to the Earth's surface and is determined by the physical structure of the antenna and by its orientation; note that this designation is totally distinct from the antenna's dire... |
57302473947a6a140053d18b | When is a magnetic fields right angles to a electrical field? | transverse wave | [
"Antenna_(radio)\n\nThe polarization of an antenna refers to the orientation of the electric field (E-plane) of the radio wave with respect to the Earth's surface and is determined by the physical structure of the antenna and by its orientation; note that this designation is totally distinct from the antenna's dire... |
573026ab04bcaa1900d7724b | What mostly affects polarization? | Reflections | [
"Antenna_(radio)\n\nReflections generally affect polarization. For radio waves, one important reflector is the ionosphere which can change the wave's polarization. Thus for signals received following reflection by the ionosphere (a skywave), a consistent polarization cannot be expected. For line-of-sight communicat... |
573026ab04bcaa1900d7724c | What reflector can change the waves polarization? | ionosphere | [
"Antenna_(radio)\n\nReflections generally affect polarization. For radio waves, one important reflector is the ionosphere which can change the wave's polarization. Thus for signals received following reflection by the ionosphere (a skywave), a consistent polarization cannot be expected. For line-of-sight communicat... |
573026ab04bcaa1900d7724d | What will you be matching with the receiving antenna's polarization? | transmitter | [
"Antenna_(radio)\n\nReflections generally affect polarization. For radio waves, one important reflector is the ionosphere which can change the wave's polarization. Thus for signals received following reflection by the ionosphere (a skywave), a consistent polarization cannot be expected. For line-of-sight communicat... |
573026ab04bcaa1900d7724e | What stays the same regarding polarization state at the recieving location? | polarized transmissions | [
"Antenna_(radio)\n\nReflections generally affect polarization. For radio waves, one important reflector is the ionosphere which can change the wave's polarization. Thus for signals received following reflection by the ionosphere (a skywave), a consistent polarization cannot be expected. For line-of-sight communicat... |
573026ab04bcaa1900d7724f | What is the name used for signals recieved following reflection by the ionosphere? | a skywave | [
"Antenna_(radio)\n\nReflections generally affect polarization. For radio waves, one important reflector is the ionosphere which can change the wave's polarization. Thus for signals received following reflection by the ionosphere (a skywave), a consistent polarization cannot be expected. For line-of-sight communicat... |
573028d604bcaa1900d7727f | Whats predictable about an antenna's geometry? | Polarization | [
"Antenna_(radio)\n\nPolarization is predictable from an antenna's geometry, although in some cases it is not at all obvious (such as for the quad antenna). An antenna's linear polarization is generally along the direction (as viewed from the receiving location) of the antenna's currents when such a direction can be... |
573028d604bcaa1900d77280 | What is a more complicated type of polarization from an antenna's geometry? | quad antenna | [
"Antenna_(radio)\n\nPolarization is predictable from an antenna's geometry, although in some cases it is not at all obvious (such as for the quad antenna). An antenna's linear polarization is generally along the direction (as viewed from the receiving location) of the antenna's currents when such a direction can be... |
573028d604bcaa1900d77281 | The polarization of what antenna is essential specification? | commercial antenna | [
"Antenna_(radio)\n\nPolarization is predictable from an antenna's geometry, although in some cases it is not at all obvious (such as for the quad antenna). An antenna's linear polarization is generally along the direction (as viewed from the receiving location) of the antenna's currents when such a direction can be... |
573028d604bcaa1900d77282 | Most rooftop antenna's are polarized in which direction? | horizontal | [
"Antenna_(radio)\n\nPolarization is predictable from an antenna's geometry, although in some cases it is not at all obvious (such as for the quad antenna). An antenna's linear polarization is generally along the direction (as viewed from the receiving location) of the antenna's currents when such a direction can be... |
57302c9aa23a5019007fcefd | What are electrical fields projected on to? | imaginary plane | [
"Antenna_(radio)\n\nPolarization is the sum of the E-plane orientations over time projected onto an imaginary plane perpendicular to the direction of motion of the radio wave. In the most general case, polarization is elliptical, meaning that the polarization of the radio waves varies over time. Two special cases a... |
57302c9aa23a5019007fcefe | What is the imagenary plane perpindicular to? | radio wave | [
"Antenna_(radio)\n\nPolarization is the sum of the E-plane orientations over time projected onto an imaginary plane perpendicular to the direction of motion of the radio wave. In the most general case, polarization is elliptical, meaning that the polarization of the radio waves varies over time. Two special cases a... |
57302c9aa23a5019007fceff | What is the name to describe polarization of radio waves varies over times? | elliptical | [
"Antenna_(radio)\n\nPolarization is the sum of the E-plane orientations over time projected onto an imaginary plane perpendicular to the direction of motion of the radio wave. In the most general case, polarization is elliptical, meaning that the polarization of the radio waves varies over time. Two special cases a... |
57302c9aa23a5019007fcf00 | How many directions does the E-plane of the radio waves oscillates back and forth? | one direction | [
"Antenna_(radio)\n\nPolarization is the sum of the E-plane orientations over time projected onto an imaginary plane perpendicular to the direction of motion of the radio wave. In the most general case, polarization is elliptical, meaning that the polarization of the radio waves varies over time. Two special cases a... |
57302ef4b2c2fd1400568a13 | What is the best for an recieving antenna for optimum reception? | match the polarization | [
"Antenna_(radio)\n\nIt is best for the receiving antenna to match the polarization of the transmitted wave for optimum reception. Intermediate matchings will lose some signal strength, but not as much as a complete mismatch. A circularly polarized antenna can be used to equally well match vertical or horizontal lin... |
57302ef4b2c2fd1400568a14 | What loses signal strength? | Intermediate matchings | [
"Antenna_(radio)\n\nIt is best for the receiving antenna to match the polarization of the transmitted wave for optimum reception. Intermediate matchings will lose some signal strength, but not as much as a complete mismatch. A circularly polarized antenna can be used to equally well match vertical or horizontal lin... |
57302ef4b2c2fd1400568a15 | What is used to match vertical and horizontal linear polarizations? | circularly polarized | [
"Antenna_(radio)\n\nIt is best for the receiving antenna to match the polarization of the transmitted wave for optimum reception. Intermediate matchings will lose some signal strength, but not as much as a complete mismatch. A circularly polarized antenna can be used to equally well match vertical or horizontal lin... |
57302ef4b2c2fd1400568a16 | A transmission can cause reduction in what? | signal-to-noise ratio | [
"Antenna_(radio)\n\nIt is best for the receiving antenna to match the polarization of the transmitted wave for optimum reception. Intermediate matchings will lose some signal strength, but not as much as a complete mismatch. A circularly polarized antenna can be used to equally well match vertical or horizontal lin... |
57303157b2c2fd1400568a37 | What requires matching of the empedance to an antenna system? | Maximum power transfer | [
"Antenna_(radio)\n\nMaximum power transfer requires matching the impedance of an antenna system (as seen looking into the transmission line) to the complex conjugate of the impedance of the receiver or transmitter. In the case of a transmitter, however, the desired matching impedance might not correspond to the dyn... |
57303157b2c2fd1400568a38 | What is the desired design value for transmmiting circuitry? | 50 ohms | [
"Antenna_(radio)\n\nMaximum power transfer requires matching the impedance of an antenna system (as seen looking into the transmission line) to the complex conjugate of the impedance of the receiver or transmitter. In the case of a transmitter, however, the desired matching impedance might not correspond to the dyn... |
57303157b2c2fd1400568a39 | Why would a transmitter have additional adjustments? | "tweak" the match | [
"Antenna_(radio)\n\nMaximum power transfer requires matching the impedance of an antenna system (as seen looking into the transmission line) to the complex conjugate of the impedance of the receiver or transmitter. In the case of a transmitter, however, the desired matching impedance might not correspond to the dyn... |
57303157b2c2fd1400568a3a | What is SWR? | standing wave ratio | [
"Antenna_(radio)\n\nMaximum power transfer requires matching the impedance of an antenna system (as seen looking into the transmission line) to the complex conjugate of the impedance of the receiver or transmitter. In the case of a transmitter, however, the desired matching impedance might not correspond to the dyn... |
573031aa04bcaa1900d77333 | What can be shorter than 1/4 wavelength long? | whip antenna | [
"Antenna_(radio)\n\nIn some cases this is done in a more extreme manner, not simply to cancel a small amount of residual reactance, but to resonate an antenna whose resonance frequency is quite different from the intended frequency of operation. For instance, a \"whip antenna\" can be made significantly shorter tha... |
573031aa04bcaa1900d77334 | What is the opposite of inductive reactance? | capacitative reactance | [
"Antenna_(radio)\n\nIn some cases this is done in a more extreme manner, not simply to cancel a small amount of residual reactance, but to resonate an antenna whose resonance frequency is quite different from the intended frequency of operation. For instance, a \"whip antenna\" can be made significantly shorter tha... |
573031aa04bcaa1900d77335 | What is at the base of the antenna? | loading coil | [
"Antenna_(radio)\n\nIn some cases this is done in a more extreme manner, not simply to cancel a small amount of residual reactance, but to resonate an antenna whose resonance frequency is quite different from the intended frequency of operation. For instance, a \"whip antenna\" can be made significantly shorter tha... |
573031aa04bcaa1900d77336 | Where is the resistance seen on the loading foil? | feedpoint | [
"Antenna_(radio)\n\nIn some cases this is done in a more extreme manner, not simply to cancel a small amount of residual reactance, but to resonate an antenna whose resonance frequency is quite different from the intended frequency of operation. For instance, a \"whip antenna\" can be made significantly shorter tha... |
5730340d04bcaa1900d77361 | What is not adjustable when it comes to a transformer? | turns ratio | [
"Antenna_(radio)\n\nSo an additional problem beyond canceling the unwanted reactance is of matching the remaining resistive impedance to the characteristic impedance of the transmission line. In principle this can always be done with a transformer, however the turns ratio of a transformer is not adjustable. A gener... |
5730340d04bcaa1900d77362 | A general matching network needs a minimum of how many adjustments to correct all components of impedance? | two adjustments | [
"Antenna_(radio)\n\nSo an additional problem beyond canceling the unwanted reactance is of matching the remaining resistive impedance to the characteristic impedance of the transmission line. In principle this can always be done with a transformer, however the turns ratio of a transformer is not adjustable. A gener... |
5730340d04bcaa1900d77363 | How many ohms are in are in a standard coax? | 50 or 75 | [
"Antenna_(radio)\n\nSo an additional problem beyond canceling the unwanted reactance is of matching the remaining resistive impedance to the characteristic impedance of the transmission line. In principle this can always be done with a transformer, however the turns ratio of a transformer is not adjustable. A gener... |
5730340d04bcaa1900d77364 | What is included between the transmission line and the antenna element? | balun | [
"Antenna_(radio)\n\nSo an additional problem beyond canceling the unwanted reactance is of matching the remaining resistive impedance to the characteristic impedance of the transmission line. In principle this can always be done with a transformer, however the turns ratio of a transformer is not adjustable. A gener... |
5730340d04bcaa1900d77365 | A balun should be integrated into what? | matching network | [
"Antenna_(radio)\n\nSo an additional problem beyond canceling the unwanted reactance is of matching the remaining resistive impedance to the characteristic impedance of the transmission line. In principle this can always be done with a transformer, however the turns ratio of a transformer is not adjustable. A gener... |
573036c4947a6a140053d2b2 | What antenna's are nonresonant? | traveling wave antennas | [
"Antenna_(radio)\n\nUnlike the above antennas, traveling wave antennas are nonresonant so they have inherently broad bandwidth. They are typically wire antennas multiple wavelengths long, through which the voltage and current waves travel in one direction, instead of bouncing back and forth to form standing waves a... |
573036c4947a6a140053d2b3 | How long are the wire antenna's that the voltage and current waves travel in the same direction? | one direction | [
"Antenna_(radio)\n\nUnlike the above antennas, traveling wave antennas are nonresonant so they have inherently broad bandwidth. They are typically wire antennas multiple wavelengths long, through which the voltage and current waves travel in one direction, instead of bouncing back and forth to form standing waves a... |
573036c4947a6a140053d2b4 | What antenna does not have linear polarization? | helical antenna | [
"Antenna_(radio)\n\nUnlike the above antennas, traveling wave antennas are nonresonant so they have inherently broad bandwidth. They are typically wire antennas multiple wavelengths long, through which the voltage and current waves travel in one direction, instead of bouncing back and forth to form standing waves a... |
573036c4947a6a140053d2b5 | What are undirectional traveling wave directions terminated by? | resistor | [
"Antenna_(radio)\n\nUnlike the above antennas, traveling wave antennas are nonresonant so they have inherently broad bandwidth. They are typically wire antennas multiple wavelengths long, through which the voltage and current waves travel in one direction, instead of bouncing back and forth to form standing waves a... |
573036c4947a6a140053d2b6 | What is the resistor equal to? | antenna's characteristic resistance | [
"Antenna_(radio)\n\nUnlike the above antennas, traveling wave antennas are nonresonant so they have inherently broad bandwidth. They are typically wire antennas multiple wavelengths long, through which the voltage and current waves travel in one direction, instead of bouncing back and forth to form standing waves a... |
5730380804bcaa1900d7739f | What is the radiation patter influenced by? | dielectric constant | [
"Antenna_(radio)\n\nThe radiation pattern and even the driving point impedance of an antenna can be influenced by the dielectric constant and especially conductivity of nearby objects. For a terrestrial antenna, the ground is usually one such object of importance. The antenna's height above the ground, as well as t... |
5730380804bcaa1900d773a0 | The ground is important for what antenna? | terrestrial antenna | [
"Antenna_(radio)\n\nThe radiation pattern and even the driving point impedance of an antenna can be influenced by the dielectric constant and especially conductivity of nearby objects. For a terrestrial antenna, the ground is usually one such object of importance. The antenna's height above the ground, as well as t... |
5730380804bcaa1900d773a1 | Whats another name for the ground? | artificial ground plane | [
"Antenna_(radio)\n\nThe radiation pattern and even the driving point impedance of an antenna can be influenced by the dielectric constant and especially conductivity of nearby objects. For a terrestrial antenna, the ground is usually one such object of importance. The antenna's height above the ground, as well as t... |
5730380804bcaa1900d773a2 | What does the artificial ground plane do for the antenna current? | return connection | [
"Antenna_(radio)\n\nThe radiation pattern and even the driving point impedance of an antenna can be influenced by the dielectric constant and especially conductivity of nearby objects. For a terrestrial antenna, the ground is usually one such object of importance. The antenna's height above the ground, as well as t... |
57303cc6947a6a140053d2f4 | What is the net quality of the ground dependent of? | topography | [
"Antenna_(radio)\n\nThe net quality of a ground reflection depends on the topography of the surface. When the irregularities of the surface are much smaller than the wavelength, we are in the regime of specular reflection, and the receiver sees both the real antenna and an image of the antenna under the ground due ... |
57303cc6947a6a140053d2f5 | What is the reason for the receiver seeing both the ral antenna and image of the antenna? | reflection | [
"Antenna_(radio)\n\nThe net quality of a ground reflection depends on the topography of the surface. When the irregularities of the surface are much smaller than the wavelength, we are in the regime of specular reflection, and the receiver sees both the real antenna and an image of the antenna under the ground due ... |
57303cc6947a6a140053d2f6 | What frequencies is associated with shorter wavelengths? | higher frequencies | [
"Antenna_(radio)\n\nThe net quality of a ground reflection depends on the topography of the surface. When the irregularities of the surface are much smaller than the wavelength, we are in the regime of specular reflection, and the receiver sees both the real antenna and an image of the antenna under the ground due ... |
57303cc6947a6a140053d2f7 | When will reflections not be coherent? | ground has irregularities | [
"Antenna_(radio)\n\nThe net quality of a ground reflection depends on the topography of the surface. When the irregularities of the surface are much smaller than the wavelength, we are in the regime of specular reflection, and the receiver sees both the real antenna and an image of the antenna under the ground due ... |
57303df4a23a5019007fcfe3 | What is the refractive index of the ground? | n=2 | [
"Antenna_(radio)\n\nThe phase of reflection of electromagnetic waves depends on the polarization of the incident wave. Given the larger refractive index of the ground (typically n=2) compared to air (n=1), the phase of horizontally polarized radiation is reversed upon reflection (a phase shift of radians or 180°).... |
57303df4a23a5019007fcfe4 | What is the refractive index of air? | n=1 | [
"Antenna_(radio)\n\nThe phase of reflection of electromagnetic waves depends on the polarization of the incident wave. Given the larger refractive index of the ground (typically n=2) compared to air (n=1), the phase of horizontally polarized radiation is reversed upon reflection (a phase shift of radians or 180°).... |
57303df4a23a5019007fcfe5 | When is polarized radiation reversed? | reflection | [
"Antenna_(radio)\n\nThe phase of reflection of electromagnetic waves depends on the polarization of the incident wave. Given the larger refractive index of the ground (typically n=2) compared to air (n=1), the phase of horizontally polarized radiation is reversed upon reflection (a phase shift of radians or 180°).... |
57303df4a23a5019007fcfe6 | Besides a ground, what has these phases apply well to? | electrical conductor | [
"Antenna_(radio)\n\nThe phase of reflection of electromagnetic waves depends on the polarization of the incident wave. Given the larger refractive index of the ground (typically n=2) compared to air (n=1), the phase of horizontally polarized radiation is reversed upon reflection (a phase shift of radians or 180°).... |
57303f5eb2c2fd1400568ae9 | what is reflected and transmitted into the ground when a plane surface is struck? | electromagnetic wave | [
"Antenna_(radio)\n\nWhen an electromagnetic wave strikes a plane surface such as the ground, part of the wave is transmitted into the ground and part of it is reflected, according to the Fresnel coefficients. If the ground is a very good conductor then almost all of the wave is reflected (180° out of phase), wherea... |
57303f5eb2c2fd1400568aea | Who proposed this theory? | Fresnel coefficients | [
"Antenna_(radio)\n\nWhen an electromagnetic wave strikes a plane surface such as the ground, part of the wave is transmitted into the ground and part of it is reflected, according to the Fresnel coefficients. If the ground is a very good conductor then almost all of the wave is reflected (180° out of phase), wherea... |
57303f5eb2c2fd1400568aeb | Is the ground has a great conductor, how much of the wave will be reflected? | 180° out of phase | [
"Antenna_(radio)\n\nWhen an electromagnetic wave strikes a plane surface such as the ground, part of the wave is transmitted into the ground and part of it is reflected, according to the Fresnel coefficients. If the ground is a very good conductor then almost all of the wave is reflected (180° out of phase), wherea... |
57303f5eb2c2fd1400568aec | What depends on the polarization and waves angle? | power remaining | [
"Antenna_(radio)\n\nWhen an electromagnetic wave strikes a plane surface such as the ground, part of the wave is transmitted into the ground and part of it is reflected, according to the Fresnel coefficients. If the ground is a very good conductor then almost all of the wave is reflected (180° out of phase), wherea... |
5730404a947a6a140053d32a | What is the portion of something that is reached by the radio transmission called? | aperture | [
"Antenna_(radio)\n\nThe effective area or effective aperture of a receiving antenna expresses the portion of the power of a passing electromagnetic wave which it delivers to its terminals, expressed in terms of an equivalent area. For instance, if a radio wave passing a given location has a flux of 1 pW / m2 (10−12... |
5730404a947a6a140053d32b | What is a measure of the power of an antenna? | microvolts | [
"Antenna_(radio)\n\nThe effective area or effective aperture of a receiving antenna expresses the portion of the power of a passing electromagnetic wave which it delivers to its terminals, expressed in terms of an equivalent area. For instance, if a radio wave passing a given location has a flux of 1 pW / m2 (10−12... |
5730404a947a6a140053d32c | What effects the function of signals received by an antenna? | direction | [
"Antenna_(radio)\n\nThe effective area or effective aperture of a receiving antenna expresses the portion of the power of a passing electromagnetic wave which it delivers to its terminals, expressed in terms of an equivalent area. For instance, if a radio wave passing a given location has a flux of 1 pW / m2 (10−12... |
5730404a947a6a140053d32d | How much power will be delivered to the reciever if the antenna has an effective area of 12 m/2? | 12 pW of RF power | [
"Antenna_(radio)\n\nThe effective area or effective aperture of a receiving antenna expresses the portion of the power of a passing electromagnetic wave which it delivers to its terminals, expressed in terms of an equivalent area. For instance, if a radio wave passing a given location has a flux of 1 pW / m2 (10−12... |
5730409004bcaa1900d77415 | The properties of a usable radio frequency can be called its? | Q | [
"Antenna_(radio)\n\nThe bandwidth characteristics of a resonant antenna element can be characterized according to its Q, just as one uses to characterize the sharpness of an L-C resonant circuit. However it is often assumed that there is an advantage in an antenna having a high Q. After all, Q is short for \"qualit... |
5730409004bcaa1900d77416 | What is a measure of the comparison between reactance and resistance? | Q | [
"Antenna_(radio)\n\nThe bandwidth characteristics of a resonant antenna element can be characterized according to its Q, just as one uses to characterize the sharpness of an L-C resonant circuit. However it is often assumed that there is an advantage in an antenna having a high Q. After all, Q is short for \"qualit... |
5730409004bcaa1900d77417 | What is the largest Q that could be achieved with a slimmer band antenna? | 15 | [
"Antenna_(radio)\n\nThe bandwidth characteristics of a resonant antenna element can be characterized according to its Q, just as one uses to characterize the sharpness of an L-C resonant circuit. However it is often assumed that there is an advantage in an antenna having a high Q. After all, Q is short for \"qualit... |
5730409004bcaa1900d77418 | What type of element would be used to encounter less reactance? | thick | [
"Antenna_(radio)\n\nThe bandwidth characteristics of a resonant antenna element can be characterized according to its Q, just as one uses to characterize the sharpness of an L-C resonant circuit. However it is often assumed that there is an advantage in an antenna having a high Q. After all, Q is short for \"qualit... |
573041e3947a6a140053d360 | What can be added to allow for an antenna shorter than the needed height to produce desired results? | loading coil | [
"Antenna_(radio)\n\nFor example, at 30 MHz (10 m wavelength) a true resonant 1⁄4-wavelength monopole would be almost 2.5 meters long, and using an antenna only 1.5 meters tall would require the addition of a loading coil. Then it may be said that the coil has lengthened the antenna to achieve an electrical length o... |
573041e3947a6a140053d361 | How would the resistive impedance from this scenario compare to if the antenna was the proper height? | lower | [
"Antenna_(radio)\n\nFor example, at 30 MHz (10 m wavelength) a true resonant 1⁄4-wavelength monopole would be almost 2.5 meters long, and using an antenna only 1.5 meters tall would require the addition of a loading coil. Then it may be said that the coil has lengthened the antenna to achieve an electrical length o... |
573041e3947a6a140053d362 | The coil has lengthed the antenna to reach how much length electrically? | 2.5 meters | [
"Antenna_(radio)\n\nFor example, at 30 MHz (10 m wavelength) a true resonant 1⁄4-wavelength monopole would be almost 2.5 meters long, and using an antenna only 1.5 meters tall would require the addition of a loading coil. Then it may be said that the coil has lengthened the antenna to achieve an electrical length o... |
573041e3947a6a140053d363 | What is the major thing that sets the size of antennas at lower frequencies? | reactance | [
"Antenna_(radio)\n\nFor example, at 30 MHz (10 m wavelength) a true resonant 1⁄4-wavelength monopole would be almost 2.5 meters long, and using an antenna only 1.5 meters tall would require the addition of a loading coil. Then it may be said that the coil has lengthened the antenna to achieve an electrical length o... |
573042dfb2c2fd1400568b15 | How big would an antenna be used to with with one m wavelengths? | 50 cm | [
"Antenna_(radio)\n\nConsider a half-wave dipole designed to work with signals 1 m wavelength, meaning the antenna would be approximately 50 cm across. If the element has a length-to-diameter ratio of 1000, it will have an inherent resistance of about 63 ohms. Using the appropriate transmission wire or balun, we mat... |
573042dfb2c2fd1400568b16 | How could the rection of output be adressed by? | changing the matching system | [
"Antenna_(radio)\n\nConsider a half-wave dipole designed to work with signals 1 m wavelength, meaning the antenna would be approximately 50 cm across. If the element has a length-to-diameter ratio of 1000, it will have an inherent resistance of about 63 ohms. Using the appropriate transmission wire or balun, we mat... |
573042dfb2c2fd1400568b17 | What unit is used to measure current? | ampere | [
"Antenna_(radio)\n\nConsider a half-wave dipole designed to work with signals 1 m wavelength, meaning the antenna would be approximately 50 cm across. If the element has a length-to-diameter ratio of 1000, it will have an inherent resistance of about 63 ohms. Using the appropriate transmission wire or balun, we mat... |
573042dfb2c2fd1400568b18 | What effect occurs when the signal is reflected back into the antenna? | reducing output | [
"Antenna_(radio)\n\nConsider a half-wave dipole designed to work with signals 1 m wavelength, meaning the antenna would be approximately 50 cm across. If the element has a length-to-diameter ratio of 1000, it will have an inherent resistance of about 63 ohms. Using the appropriate transmission wire or balun, we mat... |
5730435ab2c2fd1400568b1d | What sort of changes in material would a current reflect? | electrical | [
"Antenna_(radio)\n\nRecall that a current will reflect when there are changes in the electrical properties of the material. In order to efficiently send the signal into the transmission line, it is important that the transmission line has the same impedance as the elements, otherwise some of the signal will be refl... |
5730435ab2c2fd1400568b1e | What must match between the transmission line and elements? | impedance | [
"Antenna_(radio)\n\nRecall that a current will reflect when there are changes in the electrical properties of the material. In order to efficiently send the signal into the transmission line, it is important that the transmission line has the same impedance as the elements, otherwise some of the signal will be refl... |
5730435ab2c2fd1400568b1f | What technique is used to prevent unintentional decrease in signal? | Impedance matching | [
"Antenna_(radio)\n\nRecall that a current will reflect when there are changes in the electrical properties of the material. In order to efficiently send the signal into the transmission line, it is important that the transmission line has the same impedance as the elements, otherwise some of the signal will be refl... |
5730435ab2c2fd1400568b20 | How is this process usually used for transmission lines and antennas? | balun | [
"Antenna_(radio)\n\nRecall that a current will reflect when there are changes in the electrical properties of the material. In order to efficiently send the signal into the transmission line, it is important that the transmission line has the same impedance as the elements, otherwise some of the signal will be refl... |
573044d5a23a5019007fd031 | What is used to allow one to control the function of wave fronts moving through an antenna? | selectively delay | [
"Antenna_(radio)\n\nAn electromagnetic wave refractor in some aperture antennas is a component which due to its shape and position functions to selectively delay or advance portions of the electromagnetic wavefront passing through it. The refractor alters the spatial characteristics of the wave on one side relative... |
573044d5a23a5019007fd032 | What changes the structuak traits of a wave on either side? | refractor | [
"Antenna_(radio)\n\nAn electromagnetic wave refractor in some aperture antennas is a component which due to its shape and position functions to selectively delay or advance portions of the electromagnetic wavefront passing through it. The refractor alters the spatial characteristics of the wave on one side relative... |
573044d5a23a5019007fd033 | What is the main purpose of a refractor? | spatial characteristics | [
"Antenna_(radio)\n\nAn electromagnetic wave refractor in some aperture antennas is a component which due to its shape and position functions to selectively delay or advance portions of the electromagnetic wavefront passing through it. The refractor alters the spatial characteristics of the wave on one side relative... |
573044d5a23a5019007fd034 | A refractor can be compared to what type of viewing? | optical lens | [
"Antenna_(radio)\n\nAn electromagnetic wave refractor in some aperture antennas is a component which due to its shape and position functions to selectively delay or advance portions of the electromagnetic wavefront passing through it. The refractor alters the spatial characteristics of the wave on one side relative... |
57304708a23a5019007fd057 | What can receive a stron signal by transmitting an original wave? | actual antenna | [
"Antenna_(radio)\n\nThe actual antenna which is transmitting the original wave then also may receive a strong signal from its own image from the ground. This will induce an additional current in the antenna element, changing the current at the feedpoint for a given feedpoint voltage. Thus the antenna's impedance, g... |
57304708a23a5019007fd058 | Where will the additional current be induced? | antenna element | [
"Antenna_(radio)\n\nThe actual antenna which is transmitting the original wave then also may receive a strong signal from its own image from the ground. This will induce an additional current in the antenna element, changing the current at the feedpoint for a given feedpoint voltage. Thus the antenna's impedance, g... |
57304708a23a5019007fd059 | What is altered because of the proximity to the ground? | antenna's impedance | [
"Antenna_(radio)\n\nThe actual antenna which is transmitting the original wave then also may receive a strong signal from its own image from the ground. This will induce an additional current in the antenna element, changing the current at the feedpoint for a given feedpoint voltage. Thus the antenna's impedance, g... |
57304708a23a5019007fd05a | what happens to the reflected wave which allows the antenna to reach its asympotic feedpoint impedance? | reduced power | [
"Antenna_(radio)\n\nThe actual antenna which is transmitting the original wave then also may receive a strong signal from its own image from the ground. This will induce an additional current in the antenna element, changing the current at the feedpoint for a given feedpoint voltage. Thus the antenna's impedance, g... |
57304a52069b531400831fef | What is between recieving and transmitting antenna's? | horizontal propagation | [
"Antenna_(radio)\n\nFor horizontal propagation between transmitting and receiving antennas situated near the ground reasonably far from each other, the distances traveled by tne direct and reflected rays are nearly the same. There is almost no relative phase shift. If the emission is polarized vertically, the two f... |
57304a52069b531400831ff0 | When is the emission at maximized recieved signal? | polarized vertically | [
"Antenna_(radio)\n\nFor horizontal propagation between transmitting and receiving antennas situated near the ground reasonably far from each other, the distances traveled by tne direct and reflected rays are nearly the same. There is almost no relative phase shift. If the emission is polarized vertically, the two f... |
57304a52069b531400831ff1 | Where is the radiation patterns in the vertical plane shown? | image at right | [
"Antenna_(radio)\n\nFor horizontal propagation between transmitting and receiving antennas situated near the ground reasonably far from each other, the distances traveled by tne direct and reflected rays are nearly the same. There is almost no relative phase shift. If the emission is polarized vertically, the two f... |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.