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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.

6
votes
3answers
156 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 ...
5
votes
2answers
172 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 ...
7
votes
2answers
2k 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?
0
votes
2answers
460 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 ...
1
vote
2answers
61 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 ...
1
vote
2answers
286 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 ...
2
votes
3answers
996 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. ...
7
votes
3answers
2k 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 ...
1
vote
1answer
110 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 ...
16
votes
3answers
624 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 ...