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Questions tagged [efficiency]

Use this tag for questions that relate to the efficiency of a system or a component. The efficiency is the amount of useful work performed by the system or component (in radio applications, typically its output power), divided by the total amount of energy provided to the same.

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5 votes
2 answers
390 views

Can the reactance on a transformer load, be "corrected" on the transformer primary, to improve transformer efficiency?

The following question is regarding the ability of a transformer, UnUn or BalUn, to be efficient, if the transformer (UnUn in my case), is feeding a load with reactance, and what can be done about the ...
Louis Seaman's user avatar
  • 1,127
0 votes
1 answer
47 views

Lumped Solution for Impedance Matching vs. Ferrite Transformer

Using a high-Q LC circuit to match impedance is more efficient than a ferrite transformer, however it is very narrow banded compared to a ferrite transformer. The statement above is...?
Louis Seaman's user avatar
  • 1,127
1 vote
2 answers
208 views

What's the maximum possible "DC input to radiated RF" energy efficiency of a radio transmitter system?

It's simply a bromide amongst hams that you need to match the output impedance of a transmitter to the input impedance of an antenna, but I never thought through the implications of this until I came ...
natevw - AF7TB's user avatar
2 votes
1 answer
76 views

How Accurately Does NEC-based Antenna Software Calculate Vertical Monopole Antenna System Radiation Efficiency for "Far-Field" (Only) Conditions?

A common belief among amateur radio operators is that the radiation efficiency of a vertical monopole driven against the Earth is much less than that of an elevated, horizontal dipole of the same ...
Richard Fry's user avatar
  • 2,932
2 votes
2 answers
238 views

How to compute the efficency of an omnidirectional antenna from its gain?

Some antennas have very limited specifications with no stated efficiency. For example, this antenna has the following specifications: Frequency Band 902-928 MHz VSWR <2.0:1 Impedance 50 Ω Gain ...
DurandA's user avatar
  • 175
3 votes
3 answers
326 views

Is The Lowest Antenna Terminal Feedpoint SWR Always Optimal?

Intuition might lead one to believe that the antenna configuration with the lowest SWR(50) across its input terminals would provide the best radiation efficiency for the antenna system. But is that ...
Richard Fry's user avatar
  • 2,932
1 vote
2 answers
343 views

Does Improving Earth Conductivity Near a Buried Ground Rod Improve Antenna System Performance?

The suggestion has been made on various ham-related websites that improving the conductivity of the Earth around a ground rod produces a worthwhile improvement in the e-m radiation from a vertical ...
Richard Fry's user avatar
  • 2,932
0 votes
1 answer
70 views

What Are Some of the Most Important Characteristics Applying to the Radiation of Monopole Antenna Systems?

Such characteristics are described in Answer 1 below, as sourced in a study of antenna engineering textbooks, and by generating NEC4.2 studies.
Richard Fry's user avatar
  • 2,932
4 votes
2 answers
3k views

Calculation of transceiver current draw

My radio manual says its current draw is 22A. But in my naivety I would have calculated as follows: If the radio 'put out' 100W and I have a 13.8V supply then (using the formula power = VxI) 100W/13....
KHWP's user avatar
  • 143
2 votes
1 answer
160 views

Do Buried Radials for Vertical Monopoles Need to be No Longer than the Monopole Itself?

This is a rather common belief among amateur radio operators, but is it true? A NEC analysis provides some insight on this concept.
Richard Fry's user avatar
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8 votes
3 answers
3k views

Estimating the efficiency of a shortened (loaded) antenna

Recently I've build a trap dipole for 20/40/80m bands. I followed an article by John DeGood, NU3E and got following measurements: From balun to 20m trap: 485 cm From 20m trap to 40m trap: 362 cm From ...
Aleksander Alekseev - R2AUK's user avatar
4 votes
3 answers
1k views

Radials on a vertical, spread out evenly or not?

To have a groundmounted quarter wave vertical with a decent efficiency you need at least 16 radials. So normally you would spread them out on the ground evenly around the base. This would give an ...
ON5MF Jurgen's user avatar
11 votes
3 answers
6k views

Could a weather balloon make a good antenna?

I can't afford a massive tower, but I can get a weather balloon. What kind of set up would work best to get the maximum efficiency out of altitude?
Muze's user avatar
  • 1
1 vote
2 answers
1k views

Regulated Power Supply vs Class 2 AC/DC Adapters

I'm wondering if it would be more efficient for me to replace several AC/DC adapters (linear, non-switching) with a regulated power supply? Two of the adapters get very warm and are rated 9 watts ...
Aaron Kreider's user avatar
1 vote
2 answers
72 views

For a given transmitter mains wattage, is its TPO wattage affected by the transmission frequency?

Using a 1000 watt (mains, not TPO) transmitter capable of theoretically transmitting on any frequency, would TPO change based on frequency at which we transmit (LF, MF, HF, VHF, UHF,...)? I mean, is ...
red-o-alf's user avatar
  • 303
1 vote
3 answers
489 views

Bandwidth, Q-factor, Radiation Eff calculations

Is it possible to give approximate answers about what an antenna is capable of? There are a lot of formulas out there, but every single one I found is based on actual measurement; input, output, SWR ...
Aard's user avatar
  • 41
2 votes
3 answers
2k views

Why are variable capacitor plates made from aluminium?

This question comes from doing some research into small magnetic loop antennas for HF. For transmitting, these antennas are often designed with a big, variable, air (or vacuum) tuning capacitor (e.g. ...
captcha's user avatar
  • 1,114
8 votes
3 answers
3k views

What sort of radiation efficiency can one expect from a folded dipole?

It is pretty well established that folded dipoles have much greater acceptable-SWR bandwidth than ordinary dipoles. Radiation efficiency is simply the quotient of radiated power to the antenna ...
user's user avatar
  • 4,878
1 vote
1 answer
162 views

Comparing antenna effeciency

Let's say I have three dipoles, one is resonant at some frequency and is matched at the antenna, the second is shortened with loading coals and is also matched at the antenna, the third is shortened ...
s3c's user avatar
  • 837
19 votes
3 answers
806 views

What makes cellphone transmissions so energy cheap?

The modern cellphone can carry on a full duplex conversation for a time period measured in hours on a battery half the size of my handheld transceiver. My transceiver can barely receive for that ...
Adam Davis's user avatar
  • 12.2k