# Tag Info

### Waveguide size for 2.4 GHz

The cutoff frequency for the $TE_{11}$ mode in a circular waveguide of radius $a$ is $$F_c={c\over{2\pi}}{1.841\over{a}}$$ so for your pipe of 16 mm diameter, $F_c= 10.99 \text{ GHz}$ So as a ...
• 11.1k
Accepted

### Why do ham radio operators say that a full wave dipole isn't resonant?

Let's consider a simpler case by bringing the tips of a half-wave resonant dipole together so the two wires of the dipole are parallel, making a quarter-wave section of of balanced transmission line. ...
• 51.7k
Accepted

• 542
1 vote

### How can an RF coil emit at 3 different frequencies at the same time during Amplitude Modulation?

It's a mathematical equivalence. One of the trigonometric identities. If you amplitude modulate a sine wave, or sum 3 pure sinewaves of certain frequencies and amplitudes together, you get exactly ...
• 13.3k
1 vote

### Why does a sine wave show two peaks in the frequency domain on GNUradio?

The output of the FFT you used is complex. When you input a strictly real signal to a FFT that produces a complex result, half of the complex result is the complex conjugate of the other half (this ...
• 13.3k
1 vote

### Wavepropagation through air - EMC test values 100V/m

The test severity level is something that will be requested, or specified, between the purchaser and the supplier. In other words you don't just "comply to ISO 11452", you will have a ...
• 11.1k
1 vote

### How can an RF coil emit at 3 different frequencies at the same time during Amplitude Modulation?

The wave form is complex. It can be thought of as an infinite number of sine waves that when added together, form a complex wave. Imagine a sheet of rubber, a vibrating membrane. This membrane can ...
• 301
1 vote

### How can an RF coil emit at 3 different frequencies at the same time during Amplitude Modulation?

In the real world, there is no such thing as a zero width wall. Similarly, you can't have a radio transmission with zero bandwidth. Let's say, hypothetically, that you have a transmitter that is only ...
• 6,230
1 vote
Accepted

### Broadband dipole with no standing waves?

Any change in impedance at the end of a wire, different from the rest of a transmission-line-like wire, will reflect some current. An impedance matched resistor at the ends of a dipole won't reflect a ...
• 13.3k
1 vote

### Why do ham radio operators say that a full wave dipole isn't resonant?

I hope it's not bad form to reply at this late date, but there are a few issues I did not see directly addressed. First, any radiator of a capacitive type antenna (not just a dipole) is resonant at ...
• 361
1 vote

### Is the phase difference between the voltage and current of the standing wave on a dipole antenna constant along the dipole's length?

@Andrew, I wonder if you are interpreting this type of drawing: as a depiction of current and voltage being out of phase. To be clear, it is not; this image depicts the relative current and voltage ...
• 361
1 vote

### Is the phase difference between the voltage and current of the standing wave on a dipole antenna constant along the dipole's length?

The total current (according to physics) across any region around the antenna is the sum of the conduction current within the elements plus (according to Maxwell's equation) the displacement current ...
• 13.3k
1 vote

### Does the self inductance and velocity factor of the elements of a dipole antenna change its resonant frequency?

Note the velocity factor of the metal also doesn't appear in generic equations for inductors. The inductance is more about the permeability of the free space surrounding the conductive elements, not ...
• 13.3k

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