Antenna Theory

It is available through eBay orAmazon. See links below.

WK

2006-09-03 20:30:51 by Jose T

www.antenna-theory.com presents the analysis of the dipole antenna! The short dipole is discussed first, followed by the half-wave dipole antenna ...

I think you must do it only you with your possibility...

2006-10-11 06:23:54 by david D

Would a 1/4 wave mag mount whip antenna cut for the 144mHz ham band work for the commerical band as well (using freq. 151.715)? I am not up to speed on antenna theory just yet, but I'm getting there. If not, what would be a good design for the commerical freq. band? (for a mobile mount).

Thank You

If you want to use it for both ham and commercial it probably will work but your SWR will be a bit high on the commercial band. If you want to use it for commercial only, the good thing is that you can just shorten the antenna for the higher frequency. It would be a good idea and go out and buy an inexpensive SWR meter and then tune the antenna by cutting it off at the bottom a half inch at at time and then try it until you get a reading near 1 to 1.5 or so.

Here is a good cheap SWR meter:

http://www.mfjenterprises.com/Product.ph p?productid=MFJ-208

http://www.universal-radio.com/catalog/m eters/1889.html

http://www.universal-radio.com/catalog/m eters/1340.html

Before you go out and buy anything, just try it first on the commercial frequency and see if it well enough for you. It might be OK.

2008-06-05 20:08:45 by blackmuttracing

Price: $54.95

is this theory right:- to send a AM signal to far distances,to acheive this ,we need RF power amplifier.according to me first we should amplify the RF signals from the oscillator to required power level ,say about 5 watts.and we should also amplify the AF frequency from the microphone to required power level and the send these both high powered frequencies into a MODULATOR,which combines both FREQUENCIES and then the modulated signal sent to the antenna.IS this correct guys,or wrong,PLEASE CAN U HELP ME UNDERSTAND THIS WITH a AM transmitter BLOCK DIAGRAM!please help in my studies!

Check out the attached link, is that 3rd block diagram what you are trying to describe? The RF carrier signal is not at high power when it enters the modulator. Anyway, that should show you how things work, there's no point me paraphrasing that page. Good luck.

2009-08-11 07:05:33 by Shravan B

Theists (Christians, Muslims, etc..) often hijack the deistic argument for the existence of God: The Kalam Cosmological Argument, to support their own cultural religious baggage, but is this argument valid?

Here is the argument:
http://www.leaderu.com/offices/billcraig /docs/craig-smith1.html


my objections:

-Cause? But our understanding of causality is based on pre-existing entities and properties, which does not apply for divine creation.

-The radioactive decay of an atom is "something." This property/entity is scientifically proven to begin without a cause. There is no reason why such a thing should happen at that specific space and time, Therefore, the premise "Whatever begins to exist has a cause of its existence" is false.

-Ignorance. Without a definitive theory of quantum gravity (what happened prior to Planck time), it is impossible to conclude whether the universe began to exist. If we know for certain then why is the Planck satellite, Herschel Space Observatory, Large Hadron Collider (LHC), Laser Interferometry Space Antenna (LISA), Constellation-X Observatory, Big Bang Observer (BBO), James Webb Space Telescope (JWST), SuperNova/Acceleration Probe (SNAP), Advanced Dark Energy Physics Telescope (ADEPT), Black-Hole Imager (MAXIM) projects soon to come in the future?

-From nothing, nothing comes. A being acting on nothing cannot bring something out of it. Therefore, creation ex nihilo is impossible.

-The first premise refers to every "thing," and the second premise treats the "universe as if it were a member of the set of "things." But since a set should not be considered a member of itself, the cosmological argument is comparing apples and oranges.

-Mathematicians such as Georg Cantor and Michael Dummett have argued that actual infinites can, in fact, exist. This is a problem within mathematics, not a solved problem that the kalam argument can use without protest. As Arnold T. Guminski has elsewhere argued, the application of "Cantorian set theory to the real world…does not generate counterintuitive absurdities."

-It is a blatant contradiction to say that "God is timeless sans creation and temporal since creation." For this would mean that an atemporal, changeless being can be transformed into a temporal being.

-There is no reason to believe that a mechanical set of conditions must remain changeless. It is impossible for an atemporal being to effect anything because actions require change. There is no reason to believe that a mechanical set of conditions could not effect the same states of affairs as a personal being. Putting such limitations on immaterial properties implies that the theist can define immateriality positively, which is impossible since it is a negative term.

-An atemporal being cannot be a personal being. For an atemporal being cannot have volition/be conscious of tensed facts.
http://www.youtube.com/watch?v=pEIj9zcLz p0
wow, i see some christians still havn't graduated from the school of kent hovind

The big bang theory is an explanation for an occurrence which science can not explain. They can not tell us why dinosaurs died out but they can explain how the earth was made?

All scientific experiments are subject to the environment in which they are performed, can you answer why this is?

You attempt to make a very intelligent point, but, you fail to consider all the peramiters of the argument therefore your argument is fatally flawed.

2009-03-21 16:50:33 by AUTOPSY