# Tag Info

6

Binary PSK with instantaneous phase shifts would be equivalent to multiplying a sine wave (the carrier) with a square wave with values at 1 or -1. When two signals are multiplied, this forms a frequency mixer. A mixer with inputs at frequencies $f_1$ and $f_2$ creates outputs at $f_1 + f_2$ and $|f_1 - f_2|$. A sine wave is just one frequency, let's call ...

6

The elements of a Yagi are dipoles. If you look at a dipole at any instant, the voltage at one tip will be some value, and the voltage at the other tip has the same magnitude, but opposite polarity. So let's say at some instant, the left side is at +50V and the right side is at -50V. Consider these relative to the soil at the base of the mast, if you like. ...

6

It means the range of frequencies in which the antenna is designed to operate. Operated outside that range, the antenna may not meet its specifications. This particular antenna is a telescopic whip, a kind of monopole antenna. Such antennas are typically 1/4 wavelength long. It is advertised for 300 to 1100 MHz, and it's length can be adjusted from 24.5 cm ...

5

Marcus and Richard have answered the question that you asked, how to triple the bandwidth of a dipole, with the correct answer that it can't be done. I suggest that you edit your question to give us more information about the problem that you're trying to solve and its constraints, and then we can offer more targeted suggestions. In the meantime, here are ...

5

The data port does not carry FM signals: it carries demodulated audio. The radio performs FM demodulation and de-emphasis, and the output is heard on the speaker and is also present on the 1200 baud data output. On most multi-mode radios this port caries the demodulated audio for other mode selections as well. The data input is similar, but in reverse. The ...

4

A wide FM transmission in a narrow FM receiver is effectively overmodulation: the excessive deviation of the transmitter results in the instantaneous frequency of the transmission deviating outside the bounds of what the receiver is designed for. A practical FM receiver will pass the signal through a channel filter before demodulation. The objective of this ...

4

Unless there is a defect in the transmitting station, the transmitted bandwidth always stays the same when the power is increased. That is true even if the power is increased from 1 microwatt to 1 megawatt, if that were possible. Having said that, when you or I are listening to a 10 watt station and its power increases to 1000 watts (or more), its ...

4

You can increase the bandwidth of a dipole by adding capacitive hats (you may have to shorten the dipole to maintain a given resonant frequency). Conical hats, hemispherical hats, or hats with a circular rim will work better than short 90 degree radial spikes at the ends, or an H shaped dipole. Small capacitive hats might even raise the radiation resistance,...

4

You might experiment with increasing the diameter of the conductors of the dipole to improve its SWR bandwidth, along with optimizing the physical lengths of those conductors (equally) to center the low-SWR bandwidth of the dipole in your r-f spectrum of interest. Author edit of 14 Aug 2020: Below for "calibration" is a comparison of a case where ...

3

After simulating in CST MWS, the bandwidth was about 18.64 MHz. According to which definition of bandwidth? I'm asking this because every antenna is a tradeoff. The easiest way, probably, to deal with this is to simply reduce your requirements for what "bandwidth" is. How I can increase the bandwidth? You're using a dipole, but you want a ...

3

Design goals for a receiving antenna and a transmitting antenna can be very different. For transmitting antennas, the goals are generally efficient power transfer, directivity (a.k.a. "gain"), and efficiency. Directivity has to do with the radiation pattern of the antenna (omnidirectional or aimed in a certain direction); efficiency generally has to do ...

3

FM antennas (the sort that come with your receiver) are trimmed for best performance in the middle of the FM band. Because that band is not very wide, and the signals they receive are generally not weak, they work adequately well at the low and high ends of the band. For picking up weak signals, you'll use a broadbanded FM antenna on a mast, where there ...

2

As Phil Frost's answer already said, if the audio is at full amplitude the modulated signal will exceed the channel filter's bandwidth and the resulting audio will be distorted. From a time-domain audio processing perspective, we could describe the effect approximately as if the signal fades out whenever the modulation exceeds the passband of the channel ...

2

It appears that only reception on the 88 -108 MHz FM is being referred to. With high power FM transmitters located in the heart of a city, a 75 cm length of wire would suffice to receive stations across the band. In the case of a receiver with a telescopic antenna, it's length could be adjusted, if required, to receive weaker signals. In fringe areas, a ...

1

For a mathematical sinusoid, instantaneous frequency is the first derivative of the phase of that sinusoid with respect to time. So if the phase isn't changing at a constant rate with respect to time, the first derivative will change, and thus so will the instantaneous frequency. Also, in the real world, there can be no instantaneous discontinuous phase ...

1

Isn't the phase shift instantaneous? Ideally yes, in practice it is not. In this case, isn't the frequency constant? No, phase and frequency are related. A shift in phase is equivalent to a shift in frequency. People found that looking for a phase shift instead of a frequency shift can take less RF bandwidth for the same data throughput. Why do PSK ...

1

Bandwidth of a yagi is largely controlled by the diameter of the elements. Generally, the larger the diameter, the larger the bandwidth. However, the yagi is also helped by very slightly tapered elements. The impedance matching network may also affect the SWR bandwidth. The boom conductivity does not affect bandwidth, as well explained by Phil.

1

A more general answer... Antennas have a number of characteristics critical to their performance, including but not limited to gain, radiation pattern, impedance, and sometimes efficiency and polarization. These performance characteristics are all tied to frequency. When designing an antenna, these characteristics can be graphed vs. frequency and there ...

1

Bandwidth of an antenna is primarily dependent on the design of the antenna and the electrical radius of the active element(s). With FM radio stations, the high power 1 - 100+ kilowatt transmitters, allows a lot of loss with respect to the receive antennas: any approximately eighth wavelength wire or longer will adequately receive any station in range(20 ...

1

"A rising tide lifts all boats equally." Since bandwidth is measured in relation to the signal's peak amplitude, linear amplification alone should not increase the signal's bandwidth. Generally speaking, all frequencies produced by your source that fall in the amplifier bandwidth will increase by at least the gain of the amplifier. The amplifier's inherent ...

1

No. Part 97 (FCC rules for amateur radio) place limits on width of spectrum usage. For frequency/phase oriented modes such as AFSK, FSK, and PSK they are specified in symbol rate since increasing symbol rates (bauds) result in a widening of the sidebands created by these modes. Symbol rates / baud figures are not data rates. Multiple bits can be packed ...

1

As has been pointed out, one factor of the folded dipole that explains greater bandwidth is that it is effectively thicker. The main reason however is that it's impedance is effectively the parallel combination of a half wsve dipole and a 1/4 wave stub shorted at the far end. The reactance/susceptance of this stub varies in the opposite direction to that of ...

Only top voted, non community-wiki answers of a minimum length are eligible