I have been licensed as an amateur radio operator since about 1984.
(Before I use Club call sign YU2CCU/portable, on 2 meter and 80 meter HF, QRP.
My original call sign was YT2LTG until I obtained my extra class license in about 1990.
And become YT2HP, after my country become independent state, I new call sign 9A3HP and remain still same call sign.
I became interested in radio electronics when I was about 14 years old
and this interest persist to this day.
Can I calculate previous experiment with crystal radio?
I can never seem to get enough of "radio" in general and this is very hard for many non-amateur radio operators to understand.
But once the bug is bitten, you are usually "infected" for life.
Even though we all use radio in one way or another in our daily lives it never ceases to amaze me
how I can tickle an antenna with a small amount of energy from equipment that I have built and be easily heard on the other side of the world.
Just the thought of what is really happening is amazing.
Sure, we can all pick up our pocket cell phone miracles and call just about anywhere on the globe
but most of us don't have a clue as to what all is really happening to make that connection.
What happens when the cell phone or Internet "infrastructure" is damaged or gone?
Amateur radio needs zero infrastructure to communicate anywhere on the planet.
(Even using spark gap transmitter and simple crystal receiver.
I know how to build this simple device but work).
When my wireless fixed line provider say "But our product is ok(wireless connection) only network is not finished and you have not 3G network,
and you cannot complain to us." I say "What?
Before you know that common battery have two contact and different polarity
I have and use my own 0G network, and work with no problem"
My favorite mode is CW (radio telegraphy). Presently, I spend what little free time I have available building and operating QRP (low power) HF gear.
I get the most bang for the buck (and time) operating QRP CW gear.
A quick DX (long distance) contact on 20M (14 MHz) CW with a couple of watts of power and a piece of wire and I've had my radio fix for the day.
I am so sad because in Croatia is "mixed" CB radio, private low power radio service with real amateur radio.
(I have nothing against CB but this is not same). Also maybe I am last from my generation who really love code.
In many country CW is no longer need to know for Extra.
(My opinion is people are lazy and want turn pure amateur radios to something else,
like personal radios but now wide range
it is degradation no good
but government regulation are stupid)
Let we stay only on Morse code and small power.
Dear QRP only CW operators, I will be add new stuff
I think interested for our real hamradio operators.
Idea for QRPP in one device, also free tell others people
your idea if not Protected by law.(Copyright etc.)
Also wire antenna idea what you considered
good , usable , wire antenna.Law of psychics maybe skip
but must be proven idea.
People ask me offer "Hey man what you can invented on simple wire?"
Sorry but this is are stupid question. First invented was long wire. Simple one wire dimension (who know)
half wave dipole center feed are next step.
I think please edit me
the next major invention was symmetric antenna feed.
(you must know symmetric antenna feed are better
than any expensive coax cable,
but have unwanted radiation, I am in village
and have no trouble with my neighborhoods but in city area are something difference,
you cannot avoid interference with neighbors even use coaxial cable,
QRP CW are no trouble CW are clean signal not like SSB-SC full spectar of wide frequency.
QRP mean small power just enough to make QSO but not interfere to nobody.)
And multi band antenna(I do not like multi band antenna, because are compromise ,
you must something loose to have one antenna on many band).
It is amazing how many wire antenna can easy make and work.
And this is are simple wire??
to avoid mathematical explanation for "simple wire antenna".
I can say this Try it first then make judgment
"about simple wire antenna"
So I advice you if you can make QSO
using small power and telegraphy you do not need anymore newer more than QRP and CW.
Definition: CW mean Continuous Wave
My personally definition:
Think about, all other mode produce too much interference
It is a technical truth
If somebody do not believe to me can easy prove
First time when people who measure
electronic interference to broadcast
try your equipment
(they will be "surprise you" when you neighbor losses temper)
because broadcast signal have priority
amateur radio work on own frequency but cannot make
Interference to TV and broadcast radio.
If do this law say no transmit
it not importance "I am on ham frequency do not care for TVI"
It illegal try it(do not try penalty are huge)
Instrument say CW are clean signal, try same measure
on SSB-SC in many country you can loose your HAM license
CW and small power it is warranty that you not go in conflict
with Law or your neighbor's. It is proven many time
But you will be make good QSO
Simple Wire antenna
Hmmm,are you sure "simple"? Maybe it mean
simple to made, but physical process are not simple.
They are complex,but not visible, except when antenna
not work like we expected.
Because no point to explain all what happened in wire antenna,
I will be try explain only basic,
Current pattern,
Electric pattern
and how and why affected to impedance
Maybe ask somebody"Why we need antenna"?
"And whats with device, without Antenna
such is Cell phone?"
I say such this device not possible
only antenna is integrated inside and not visible
(USB Wlan device look like no antenna,
but try open it, you will be found transceiver chip,
transceiver antenna is integrated.
Same technique is in your GSM phone)
The antenna converts the energy into radio waves
that radiate into space from the antenna
at the speed of light.
The radio waves travel through the atmosphere.
or space until they are either reflected
by an object or absorbed. If another antenna is placed
in the path of the radio waves, it absorbs
part of the waves and converts them to energy.
This energy travels through another transmission line
and is fed to a receiver.
This is short description
In reality all this weak points.
Any of description part if are not work properly
result is bad reception. Because
reciprocity law "what is good for transmission
work well on receive."
Next:development
Developed dipole antenna- Back to the history
single wire feed dipole
When people figure than 1/2 wave of wire can do much more
than random wire length.(resonance)
There is appear problem how to feed this antenna? Simple wire antenna,
and you have on end maximum voltage, almost zero current
and maximum impedance(I have in my collection military antenna end feed.
When I make snap shoot I will publish )
But in center of this antenna current are maximum and no electric voltage.
The single wire feed dipole work in principle, feed wire are connected
not in center, just a little from center, feed wire are not same like antenna wire diameter.
This work good but have trouble, any move of feed wire affected to impedance.
Also feed wire pick up to much interference it is huge problem in city area.
Also this feed wire radiate energy too much. In the village there no this problem.
(Do you know fact, Titanic have single wire feed dipole
and dimension of Titanic also antenna result
that today Navy distress frequency is 500 kHz)
This single wire antenna work well
if you live far a way from electromagnetic source
like me on village(also I have no neighbors with TV set)
If you work only QRP CW and nobody
make you interference this simple antenna work.
But there is become problem,more power lines,
telephone cable and how to solve unwanted radiation.
There is are need something new , how to feed dipole antenna.
Open Symmetric feed
"chicken step" because look like design for chicken
Dipole design for lower band, and you have first multi band antenna(because most HAM bands are harmonic.
Except 21MHz , new bands are not exist in this time).
But anyway how symmetric feed can work?
Because line loss are less than expensive coaxial cable.
When antenna work like 1/2 wave there is nothing new ,
but when work like 1 wave length,
you have maximum electric voltage and minimum electric current
this mean high impedance. But length of symmetric feed
are design to make transformation effect.
This is answer. But.....
This feed line to much radiate and pickup unwanted radiation.
Even shielded symmetric feed line not answer.(losses to much energy)
Yet for TV reception symmetric feed was in use many years.Have a minimum loose
and not expensive.
So coaxial cable is logical step.
But dipole are need symmetric feed and coaxial cable are asymmetric.
Wrong thinking that additional element for transformation
and symmetrization are not need.
If RF current go to the shield, coaxial cable also radiate energy and pickup unwanted radiation.
There is are another feed line wave guide
(but for UHF and more, for HF it is not interested).
The Impedance
And most common error in antenna techniques
and all what you need to know about simple antenna.
OK you can become Phd of Physic, because you can explore this stuff.
But let we stay only to practice knowledge and basic.(Most HAM operator are not
scientific educate, but must know with understand basic, specially if you deal with small
power. If you transmitter measured by hundreds or thousand watts who care, continue
with making EM pollution, because thats it really no hard feeling to people who use more than
5W output.
Something about "Who care"
In Astronomy are in use funny measure for distance
They say light year,(ly because km and miles are to small units, even many time light year is too small and they use another big units) distance what radio signal travel
in one year.So 1 light year exactly 9,460,730,472,580.8 km
(radio signal travel same speed like light) See in Wikipedia, or some other source
So first experiment, radio signal travel only (honestly not first but official) transatlantic communication
this signal now(June the 1st 2010)1,031,890,973,150,629.6 kilometers far a way from Earth.(can you even read this number?)
So when you talk on any kind radio(including your mobile phone)
think how far your signal go.
To proper use antenna following criteria must respect:
also symmetric asymmetric feed point are importance
Many people feed 1/2 wave dipole in center using asymmetric coaxial cable?
Sorry no hard feeling, this is totally wrong approach
I see even older HAM operator who think "who care and this is energy loose 0.5 dB on balun"
What really happened when antenna are symmetric and everybody know coaxial cable not?
Now you see, not only antenna radiated and pick up radio waves, one part of coaxial line do same.
This happened any time when somebody try against law of physics.
But we see this because VSWR are not in normal value, also metallic parts of our radio transceivers become hot
and really can make burn injury. Like I say you cannot against law of physics, same happened on wrong
connected TV antenna, and you have angry neighbor on your door step. Maybe your TV antenna work perfect
(any way you are amateur radio operator and know how connect coaxial cable and antenna. but your neighbor dont know)
near your HAM antenna, and neighbor's 50 or more yard distance have trouble in reception TV signal, when you
make contest or DX. Same problem neighbor TV antenna not connected properly, and shield of coaxial cable pick up
your HF signal, overload mixer in TV set and somebody knock on your door.
We can see on simple VSWR, that something wrong, but who make measure on TV antenna? And 2 or more antenna preamplifier's
in chain(serial connected). Some studies say that less than 20% TV antenna installation are connected proper
80% are totally wrong(no wonder how many angry neighbors knocking on doors many HAM operators).
Only because people not use balun for TV antenna(really cheap and can be easy hombrew)
This is most common Balance-Unbalance (so we have balun). It can be depend 1:1 , 1:4 (most common in VHF/UHF technique)
also in TV antennas.
Also antenna feed in point like 30% from one end (FD4B multi band antenna) need special matching, because this point are
not symmetric, and not (like coaxial line asymmetric) they are between, and connect points on balun if wrong connect
this balun cannot work. Chance to wrong connect only 2 contacts are 50/50 %
Look like stupid but I am also do this simple mistake(and wonder why antenna do not work?)
Dou you know?
Painting an antenna - Many people think TV antennas are unattractive.
Will painting an antenna to make it less visible affect the way it performs?
No. Dielectrics affect antennas, but a layer of paint is too thin
for this effect to be significant. Many cell phone antennas are painted black.
HAM radio operators often use long-wire antennas that have an enamel coating.
Warning!
Don’t use a paint that has embedded metals (metallic flakes, red oxide, graphite, carbon). Enamel paint is best.
Rustoleum is a good choice.
Do not ask me why I am put this on my web. Because many people use antennas
and basic
things never will be understand.
99.99% people think "O yeah , antenna this is only conductive material, wire or etc."
Totally wrong conclusion.
Antenna can be following: conductor, good insulation too, even "empty" space(radar microwave antenna).
(Material between, not good conductor or not good insulator are not included).
How this possible? On very high frequency good insulator work well like directed antenna.
How? Are you put stick in the water and see straight stick become "broken".
Water conduit ligh, air too. But not same speed this give you false image "stick are broken".
If you try change vision angle. What happened?
In some point you are not able to see under water.
Back to stick made of good insulator material, what will be happened.
If diameter and working frequency are in some correlation,
simple dipole for this microwave frequency implemented in one side this stick, and must have some metallic reflector,
will work like wave guide or maybe easy to compare Yagi antenna. But why?
Simple radio wave cannot leave insulator and travel same like in "ordinary wave guide"
(metal pipe and radio wave cannot live because have reflection from metallic wall)
Same will be in good dielectric stick, act like wave guide. Difference between metallic waveguide and dielectric stick,
waveguide become wider on side provide to radiate(horn antenna) and dielectric stick same like Yagi antenna,
(elements become shorter, and dielectric stick smaller diameter). Because angle of radio waves are to small
cannot brake barrier between two difference material, air and stick have difference dielectric constant.
Also radio wave are have no same speed.
This is not weird, rather can we say normal on microwave (you have still "coils, capacitor, resonant circle" and so one.But not visible, all process are same in any frequency.)
This is I write like continuation , "Idea I was paint my antenna".
Short story - long story.
On HF we can use wire with no insulation or wire insulated in some of synthetic material.
Do not paint insulators on HF wire antenna , why? There is no paint good insulator, even can be paint that has embedded metals,
you kill your insulator, lose quality.
I am previous write long articles on the Ham Radio Croatia web. But for English people not for use.
On HF all process in basic are same (same law of physic). But on HF antenna are very big construction
and everything make interference, ground, building, electric power lines even tree etc.
And what happened?
Long story - short story.
Your TV antenna(also VHF and UHF antenna) are many lambda far a way from ground, buildings, power lines, tree etc.
But on HF it is not possible lift your antenna few lambda from ground surface.
Also roof of buildings have conduits on the top,
so ground level become from higher near building, look like impossible task.
You must understanding, radiation pattern, impedance, resonance etc.All this depend of neighbors fence, house, with everything too close.
All this change, and even you make precise calculation and on such this frequency one inch plus or minus do not affect nothing
(simple dipole antenna on HF become longer because material,wire, become long after some time ,
because antenna wire+coaxial feed+wind,snow are very heavy and stretch the wire more than you expected,
also outside temperature change dimension your antenna).
Much more level antenna from ground affect to reception and transmitting.
(In my case 14 MHz this mean 40 meters high dipole to say now nothing interfere).
Some times are very low antenna pick up DX signal better than expensive antenna system.
My favor HF is 20 meters and really ratio DX and antenna simplicity are so interested.
This is not possible found in literature only in Ham literature you can found this.
Professionals skip this effects and all irregulars.They use high power, strong signal and wide free band.
But really who make first oversea communication using small power? Ham radio operators.
Professional force high power on to low frequencies (long waves).
So we cannot make replica professional efforts, power limitation, weak signals, narrow bands,
and enemy No 1 Ham radio, is weather(also misunderstanding basic principle).
.
To match or not to match, that is are question?
Really I am not good in classic novels
but doubt in Hamlet,
"To be or not to be"
or to match or not to match?
Manny ham radio operators are familiar with,
some kind match units, simple device.
But how simple? In reality look like simple people
home made this device to make better their antenna.
Improve antenna, really? Not just snap fingers.
Back to previous content:"Impedance, antenna=transmission line(coaxial cable today most)
=Transmitter/Receiver".
But what in case when this simple rule are not respect?
Coaxial line are always same, transmitter/receiver too, but antenna?
whats happened in antenna?
I will be try from www.hamradio.hr translate my old post
SWR 1:1 is possible if in the feed connection point
reactant are 0 and antenna are resonant on this frequency.
If no resonance antenna, then antenna have reactant and SWR 1:1 show because
feed line can add or cancels reactant,
and actually in resonance are not only antenna,
feed line and antenna are together in resonance
(this is also not good I will try explain why).
Transformation effect feed line make
many mistake and misunderstanding.
Resonant frequency is possible only if reactant are almost 0 or no reactant at all.
Lowest SWR are often not on the place lowest reactant. This happened when
impedance antenna not same like feed line.(Antenna are really resonant on desired
frequency, but impedance of antenna not under desired value).
Impedance,,,,,can be pure or complex composition together between pure resistance
and reactant resistance.But SWR cannot be 1:1 if you have reactant
(reactant cannot radiate energy, rater energy are burn and become heat energy)
Often wrong conclusion are SWR 1:1 if antenna have 50 ohm but resistive plus reactant.
(1/4 lambda most people feed direct, but cable is 50 ohm, and 1/4 are pure resistance
around 36 ohm, but work. How? Everybody know velocity factor,
and antenna must be some short than really 1/4 lambda or no SWR 1:1 and difference
between really velocity factor and how people make this antenna are little difference
exactly for some reactant "need" for SWR 1:1).
If you have antenna pure reactant no resistive component at all,
not possible reach SWR 1:1 , usually in this case are in "red" mean too high reflection.
Another very importance and often misunderstand are:
I was cut coaxial cable on some value and reach SWR 1:1
and previous I was have SWR to high.
(Only one thing are for sure , you do not to much cable only from antenna to your transmitter)
Back to reality, feed line long 1/2 lambda(consider velocity factor)
make exact copy SWR your antenna
minus feed line loose
1/4 ,3/4, 5/4 etc. make strong transformation effect.
Anny length of feed line also make transformation.Only 1/2 and multiplied dimension are
able to make "photocopy" impedance of your antenna(minus loos energy in cable).
This is reason why I was start using antenna(wire antenna) no feed line, everything
was antenna wire direct connected in match box.
Of course I am not Nobel prize winner, just in practice use old proven technology.
But feed line between match box and antenna if Z antenna=Z feed line=Z Tx/Rx ,
SWR cannot depend of length feed line, if depend usually Tx/Rx and feed line are not
problem, problem is antenna.And you have following trouble:
1. Coaxial cable have RF current and radiate,when you on receive shield receive
unwanted signals(you can coaxial line have on bunch or all stretched in line same
nothing cannot change, or if you touch your transceiver also, but if change no good).
2. Impedance from your transceiver to antenna not same in all points
must be Z Tx/Rx=Z feed line=Z antenna
3. Coaxial cable have too much loose energy(it is not depend on fact that you spent bunch of money to buy expensive cable, you are waste money"
So sentence "I was cut my coaxial cable to some dimension and now I have SWR 1:1"
Nice to hear but far a way from reality.
And this "simple mistake" do young but also old people.
But what is reactant, what is resonance, what is impedance?
Impedance is dynamic resistance and have 3 component, actually 2
Inductive and capacitive, when they each other canceled, we have pure resistance.
So what inside the antenna tuner, or match box, named how you like.
Nothing than I previous explain in long text, but counter pair. If antenna have capacitive
reactant, inductance inside match box will help you to reach resonance.
If antenna have inductive reactant, capacitor inside match box will do same.
Minimum need this
usually configuration:
Most used and give you good result.
Advanced configuration:
Any can be used for coaxial cable or single wire too. But if have a parallel feed line
you will be need transformer (mostly 1:4 ) , terminal for single wire are connected
same like center contact on coaxial connector. Balance parallel feed line need symmetric
output, most this tuner have only 1:4 ratio, mean input coaxial 50 ohm output symmetric
200 ohm.
Once I was say if no feed line, direct contact single wire antenna on tuner it is much more
better than if between tuner and antenna have long coaxial cable
(too much loose energy even tuner work well).
Only one benefit for transmitter is no more standing waves on PA stage.
"So what" will be say people who anywhere use high power, looking QRP transmitter(again
wrong, first time they make wrong "Huh this is only 5 W you cannot work serious QSO")
they forget reciprocity principle, what good for transmitting same good for receiving.
Really power not need to make good QSO, only what we need are signal not high power.
Transmission line, resonance and antenna
Basic principle
How stuff work? How to kill reactant?
"Extra problem for Extraordinary"
Many people cannot understand
dBi: = Gain of antenna with respect to isotropic antenna given in dB = 10 log (power max / power isotropic)
dBd = Gain of antenna with respect to a dipole antenna given in dB = 10 log
(power max/ power max of half-wave dipole antenna)dBi = dBd + 2.15 dB
How is possible "underwater level of knowledge"
But this is to complicate maybe.
maybe basic understand is better. Very fast we will be from basic go to some more knowledge.
End feed antenna, and what happened..
If you on coaxial line connect conduit shorter than 1/4 lambda this conduit acting same
like capacitive, 1/4 lambda pure resonance low impedance ,acting like serial resonance(capacitive and inductive),
little longer than 1/4 and shorter than 1/2 lambda acting like coil ,
inductive.
Exactly 1/2 lambda are pure in resonance, high impedance , acting same like coil and capacitor in parallel.
Longer than 1/2 lambda and shorter than 3/4 lambda act like capacitive,
3/4 lambda have low impedance and act like serial resonance , capacitive and inductive.
Longer than 3/4 lambda and shorter than 1 lambda act like inductive.
1 lambda is same like 1/2 lambda pure resistance very high.
But why people use 5/8 lambda? This is some longer than 1/2 lambda, pure resistance.
And 5/8 lambda have capacitive reactant!?!?!?!? Yes correct. But why to do "mismatch"?
Answer is 5/8 lambda have maximum useful radiation patern. This is only one reason
But this antenna is capacitive and must have coil to add inductive component,
this is serial resonance and have low impedance.
(Warning people, many got professional 5/8 lambda from some military or police frequency
this stuff look like easy make to work on 144 MHz just a little adding longer rod.
Wrong , wrong and another wrong. This antenna to short for amateur band, have "wrong" coil in base
It work on higher frequency good, but on low frequency like HAM have two major trouble.
First rod is too short,(OK this is easy part) another design base coil is for much more high frequency.
To call something 5/8 lambda antenna must have, rod+coil+mast = 5/8 lambda comparing velocity factor.
Reason is radiation pattern , pure 50 ohm impedance. You cannot obtain this using antenna 5/8 lambda , example, for
160 MHz(I have such this from UN Force) or VSWR is bad , or if you add something longer rod , forget good radiation pattern
and pure 50 ohm impedance
radiation pattern isn't like expect for 5/8 lambda and/or
if you have pure resonance, impedance is or low or high.
All this is about adding capacitive or inductive reactant.
Rules are 1/4 , 3/4 lambda have low impedance,no need transformation to coax
1/2 lambda, 1 lambda have high impedance need transformation.
Any other value between need or coil or capacitor to get antenna in resonance
5/8 lambda need coil to put additional inductance to match with capacitance.
Antenna too short than 1/4 need also base coil.
Coil can be on top also, but this coil need capacitive load because on top there is no electric currency.
Coil can be in half or any place, from base to top antenna, for mobile antenna is most useful in base
only for mechanical reason.(Not ideal current voltage and radiation.But antenna is strong to mechanical force.)
All antenna can be one coil.
Try to memorize this, it is very good in practice.
Now your are able to follow
whats happened in vertical antenna or horizontal end feed wire.
Huh really big science, but many people unable to understand simple fact.
When I say law of physics, many high educated people in my country now consider me "State enemy No 1 "
But when people with big experience say "We use simple wire and make good QSO with only 5W"
How this possible?Just a little mismatch, in coaxial cable make huge loose energy, even exact match antenna,
coaxial cable and Transceiver also loose energy.
Logical conclusion is , best transmission line (usually coaxial cable) no transmission lines at all or
short as possible.
What happened on simple 1/2 lambda dipole. How is possible end feed, center feed, or like FD4B out center feed
so cal OCF , nothing else 1/2 dipole for low band
or Windom antenna or call what you like
use simple rule 4 amateur HF bands are harmonic
3.5 MHz , 7 MHz , 14 MHz and 28 MHz
21 MHz and new bands isn't harmonic. But for
commercial reason many try to to "rape physic law".
Simple just pick up point, where is impedance interested for your application. That's all.
Who say "dipole must be cut in center and feed in center".
Rules of physic never say such this.
When I say "best feed line is much more short or no feed line"
I am no joke. There is no ideal feed line with zero
looses.
and what missing?
Wawe guide(have almost zero looses
but not possible to use below GHz).
Wawe guide is same like "chicken step"
try imagine that dimension of rectangular wawe guide
is folloving, two parallel metalic walls are exact 1/4 lambda
so they act like very good insulator,
another two walls is nothing than symetric parralel line.
It work good on milimetars lambda, in HF cannot be used at all.
For now is something what many people cannot understand. But this is new thematic
"I hear you 59+60db"
or
"ur RST is 599 +60db"
How nice to hear, but is it for real??
We know fact (see decibel / gain scale on my web or some other source)
6db=1 S-unit=power is for time difference.
To achive only 1 S-unit transmitter on other side must increase radiated power 400%.
Example from 100 Watt need run 400 Watt.
If your S-meter show signal strength 9+60db
for just a little increase transmitter power from other side
you need calibrate S-meter again , even factory made it.
So 60db need 4000% increase power of your corespondent.
If you hear 599 when he work with 100 Watt ,
he must run transmitter using 4000% or 40 time more.
Play with numbers and see what is possible and what impossible.
1000Watt vs 1Watt
Teoretical facts:
-An "S-unit" on receiver's S-meter or RST system consist of a 6 decibel
increase or decrease of output power recived from transmitter.
-Power needs to increase four time or 400% to result in a only 1 S-unit or 6db.
-Reducing output power down to 25% of previous decrease only 1 S-unit or 6db.
-10db increase in signal strenght need power increase ten time!
-RST system was designed origginaly for human ear
an was based on typical reciver performance of over 50 years ago.
-Today receivers can receive tehnicaly "weak" in db signal
to sound good(RST569 RST579) to the ear.
This is a mathematic, no cheating;
S9+10db = 1000 Wats output
S9 = 100 Wats output
S8 = 25 Wats output
S7 = 6,25 Wats output
S6 = 1,56 Wats output
S5 = 0,39 Wats output
and so one.
We can see that it becomes easy to play games with such numbers. For
example, an RST of 439 is a legitimate report which permits reasonably
effective communication. But, do we believe that the transmitting station
illustrated above could really produce a 439 signal by running .0013 watt?
If we
say "probably not", we also ask why not, and then we would get the seminars
about perfect antenna matching, transmission line losses, and so forth.
RST439 produce 0,0013 Wats output
Most commercial transceivers have typical
output in the 60-200 watt range, and S8-9 reports are taken for granted.
Actually, 15-25 watts is a far more practical operating power than most
amateurs and equipment vendors realize today...and the thousands of QRP
enthusiasts will confirm that getting a solid 579 running 3-4 watts is no big deal.
Some people use QRPP and microwatt transmitters.With the world
record set in 1970 between Alaska and Oregon on ONE(1) microwatt, think about
it this way: your 5Watts QRP transmitter is incredible much more times
powerful than the transmitter used in that historic test!
Some people say we are the ham radio operators, and they use proverb on many electronic or ham forums
"Life is too short for QRP"
After reading this fact I can say:
Life isn't too short for QRP.
Why 50 ohm?
The best coaxial cable impedances in high-power, high-voltage, and low-attenuation applications
were experimentally determined in 1929 at Bell Laboratories to be 30, 60, and 77 ohm respectively.
For an air dielectric coaxial cable with a diameter of 10 mm the attenuation is lowest at 77 ohms
when calculated for 10 GHz.
CATV systems were one of the first applications for very large quantities of coaxial cable.
CATV is typically using such low levels of RF power that power handling and high voltage breakdown characteristics
were totally unimportant when compared to attenuation.
Moreover, many CATV headends used 300 ohm folded dipole antennas to receive off the air TV signals.
75 ohm coax made a nice 4:1 balun transformer for these antennas as well as presented a nice attenuation specification.
But this is a bit of a red herring: when normal dielectrics are added to the equation the best loss
impedance drops down to values between 64 and 52 ohms.
30 ? cable is more difficult to manufacture due to the much larger center conductor and the stiffness and weight it adds.
The arithmetic mean between 30 ohms and 77 ohms is 53.5 ohms, but the geometric mean is 48 ohms.
The selection of 50 ohms as a compromise between power handling capability and attenuation
is generally cited as the reason for the number.
Remember 1:4 transformer widely used in amateur antenna systems are litle out from specification.
Folded dipole is usually 300 ohm, and 50 ohm × 4 = 200 ohm. Difference between 300 and 200 ohm
usually many people forget, or do not know at all.
50 Ohms works out well for other reasons, such as that it corresponds very closely
to the drive impedance of a half wave dipole antenna in real environments,
and provides an acceptable match to the drive impedance of quarter wave monopoles as well.
73 ohm is an exact match for a centre fed dipole aerial/antenna in free space
(approximated by very high dipoles without ground reflections).
RG-62 is a 93 ohm coaxial cable, originally used in mainframe computer networks in the 1970s and early 1980s.
It was the cable used to connect the terminals (IBM 3270) to the terminal cluster controllers (IBM 3274/3174).
Later, some manufacturers of LAN equipment, such as Datapoint for ARCNET, adopted RG-62 as their coaxial cable standard.
It has the lowest capacitance per unit length when compared to other coaxial cables of similar size.
Capacitance is the enemy of square wave data transmission and is much more important than
power handling or attenuation specifications in these environments.
All of the components of a coaxial system should have the same impedance
to reduce internal reflections at connections between components.
Such reflections increase signal loss and can result in the reflected signal reaching a receiver
with a slight delay from the original.
In analog video or TV systems this visual effect is commonly referred to as ghosting.
Signal leakage is the passage of electromagnetic fields through the shield of a cable and occurs in both directions.
Ingress is the passage of an outside signal into the cable and can result in noise and disruption of the desired signal.
Egress is the passage of signal intended to remain within the cable into the outside world
and can result in a weaker signal at the end of the cable and radio frequency interference to nearby devices.
For example, in the United States, signal leakage from cable television systems is regulated by the FCC,
since cable signals use the same frequencies as aeronautical and radionavigation bands.
CATV operators may also choose to monitor their networks for leakage to prevent ingress.
Outside signals entering the cable can cause unwanted noise and picture ghosting.
Excessive noise can overwhelm the signal, making it useless.
An ideal shield would be a perfect conductor with no holes, gaps or bumps connected to a perfect ground.
However, a smooth solid copper shield would be heavy, inflexible, and expensive.
Practical cables must make compromises between shield efficacy, flexibility and cost,
such as the corrugated surface of hardline, flexible braid, or foil shields.
Since the shields are not perfect conductors, electric fields can exist inside the shield,
thus allowing radiating electromagnetic fields to go through the shield.
Consider the skin effect.
The magnitude of an alternating current in a conductor decays exponentially with distance beneath the surface,
with the depth of penetration being proportional to the square root of the resistivity.
This means that in a shield of finite thickness, some small amount of current
will still be flowing on the opposite surface of the conductor.
With a perfect conductor (i.e., zero resistivity), all of the current would flow at the surface,
with no penetration into and through the conductor.
Real cables have a shield made of an imperfect, although usually very good, conductor,
so there will always be some leakage.!!
The gaps or holes, allow some of the electromagnetic field to penetrate to the other side.
For example, braided shields have many small gaps. The gaps are smaller when using a foil (solid metal) shield,
but there is still a seam running the length of the cable. Foil becomes increasingly rigid with increasing thickness,
so a thin foil layer is often surrounded by a layer of braided metal,
which offers greater flexibility for a given cross-section.
Answer why 50 ohm is , easy to made and not to bad work we can say possible.
You can found special coaxial cable more than hundred ohm(car radio) but this is very short cable.
High impedance need small diameter inner conduit and this isn't good for power cable.
Exact 30 ohm is not easy to manufacture(very small distance between shield and inner conduit,
it must be too precise and become too expencive). Break down voltage is much more low than 50 or 75 ohm
(small impdance small distance between inner conduit and shield, high impedance need too tiny inner conduit ,
small power can be used)
Very practical reason is why 50 ohm. It is near ideal, but possible to manufacture.
This is answer Why 50 ohm.
PiHRAB-1
Amateur high altitude balon.
o yes in 9A we try amater high altitude baloon
if you mastered in Croatian language see:
Short story
Greetings
,
It is my honor to inform you , about first amateur radio high altitude balloon project
performed by Croatian amateur radio club Bjelovar 9A1GIJ / 9A9D June 13 2009, at
07:30 GMT from sport airport Brezovac near Bjelovar city location coordinate
45.51.39 N, 16.50.09 E
Expected is:
Estimated fly time: 3 hours
Estimated maximum altitude: 30 000 m
Possible landing zone: circle in radius 2000 m from airport, fly start point.
Payload weight: 1,5 Kg
Balloon weight: 600 g
Gas charge: Helium
Payload contents: transmitter 145.200 MHz, output power 300 mW, GPS receiver (3-D position, altitude, speed),
APRS, various sensors (temperature inside electronic box, outside temperature, battery status), battery power, antenna
Payload is equipped: sound and light signals, radar reflector size 20x20x10 cm, parachute 48''
Protective material for payload: polystyrene, cover with tin Aluminum alloy
People in project: 6
Down link frequency: 145.200 MHz, Packet radio
Received data from telemetry in balloon and final results:
Distance from the start to landing zone: 108 km
Minimum temperature outside electronic box: -28 C
Minimum temperature inside electronic box: 16 C
Maximum altitude: 18 751 m
Telemetry signal received from locator fields: JN95AD, JN75EI, JN75XT, JN85FB,
JN75DX, JN75SK, JN95AE, JN85IW
Fly time: 1 hour , 17 minutes
Maximum speed: 163 km/h
Speed of descent by parachute: 5-6 m/s
Landing zone:
45.1141667 N 17.7080000 E, locator field JN85UC
Payload are recovered thanks to amateur radio from E7 especially E73DL
June , 17 2009
For the first project, high altitude amateur radio balloon is something new.
New project PiHARB-2 is on the developing phase now.
73 de 9A3HP
On my idea number 2 will be equiped with, homing beacon,and HF beacon, the best frueqency for maximum range
you can free give me and team advice on my e-mail
Thank you, wish you best DX. The HF beacon will be QRPP and CW
Big success for smal country 9A Croatia.
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