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5 votes

DVB reception: Why do I need to add a coaxial cable to my installation to improve SNR of the signal?

A dipole antenna requires a balanced RF input. A standard coax is an unbalanced cable but, over a certain length it can, under some circumstances, offer a more balanced impedance to the dipole antenna ...
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4 votes

Where is the positive and negative on a telescopic antenna?

Halfway between left and right halves of the \$1/2 \lambda\$ dipole is a point in space that has zero electric field. This is shown by the green line in the picture below: - So, you can discard 50% ...
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4 votes

Where is the positive and negative on a telescopic antenna?

By grounding one end of the half wave dipole antenna shown in the question, one can obtain a quarter wave monopole antenna. And a whip antenna (including telescopic antenna) is a type of monopole ...
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2 votes
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Impedance match a NFC Antenna to 50 \$\Omega\$

I could he wrong, but I think that attempting to accurately impedance match a near field antenna to a transmission line or device might be somewhat of a wild goose-chase. One may need to just accept ...
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2 votes

DVB reception: Why do I need to add a coaxial cable to my installation to improve SNR of the signal?

You get a very bad SNR when connecting the antenna directly to the DVBT receiver and a better SNR when using a longer cable? Of course antenna impedance, cable impedance and receiver input impedance ...
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2 votes

DVB reception: Why do I need to add a coaxial cable to my installation to improve SNR of the signal?

Probably an effect of impedance mismatch. Things with an interface where electromagnetic waves leave or enter have a wave impedance. That is just a number that denotes how the magnetic and the ...
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2 votes

Can I solder a wire antenna to the exposed PCB antenna of a BBC Micro Bit to boost its bluetooth signal?

Sure you can. Cut the trace antenna and solder a suitable 50 ohm 2.4ghz tuned antenna to it, and ground. But should you? You may find that you have little to no performance increase. The trace antenna ...
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1 vote
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Does a receiving antenna radiate the power received?

If the incoming E-M wave can induce a voltage won't it accelerate or decelerate the electrons in the wire and doesn't this acceleration cause further radiation (lets call it secondary radiation) of E-...
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1 vote

Active Radar Homing with single antenna

It depends how complex you want to go. A "typical" tracking Radar will implement a Twist Cassegrain antenna, with a monoupulse feed/comparator. It creates 3 channels; Sum, Difference Azimuth ...
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1 vote
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Active Radar Homing with single antenna

First of, note that target tracking was done with radar systems from day one, long before ESAs came on the scene. One way is to use monopulse tracking. In order to determine angle of arrival (AoA) of ...
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1 vote

Active Radar Homing with single antenna

At radar frequencies, phased array antennas don't have to look like multiple, separate antennas. If you take off the radome, you'll probably find a printed circuit board with multiple elements and a ...
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1 vote
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How to choose a sweep range for a known and unknown device with a VNA?

With just a VNA, you're only able to check the impedance match of the antenna, not its radiation pattern, gain, or other characteristics. If you know the intended frequency range for use, there's no ...
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1 vote
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end-fire antenna array: find the angles of the fire-end array for the minor Lobe maxima

You are on the right track with your array factor: but I get \$AF = \frac{sin(\frac{N}{2} kd (1-cos\theta))}{sin(\frac{1}{2} kd (1-cos\theta))}\$ with my \$\theta\$ measured from endfire. These may ...
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1 vote

Diode SPICE data accuracy at high frequencies?

You cannot extrapolate Spice data where geometric impedances affect the conductance and junction capacitance assumptions in the datasheet. "Measured at a LO frequency of 9.375 GHz, with an IF ...
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