Transmitter power questions.....

[bravo52]

Bob,
   Not sure on the questions.  I'm just answering the questions on their
"standard" list.  There are others I didn't include like location, altitude
of the transmitter, ect....... I do know they map all the transmission on a
base so it may have to do with knowing what is being emmitted.  Other than
that, I don't have specifics.

v/r
Jerry L.

----- Original Message ----- 
From: "Bob Richards" <bob at toprudder.com>
To: <discussion at nsrca.org>
Sent: Monday, April 11, 2005 9:10 PM
Subject: Re: Transmitter power questions.....


>
> I'll echo most of what you say, Bill.
>
> I've seem to remember that the power was limited to 1
> watt into the final output stage. Actual power
> delivered to the antenna will be less than 750mW.
>
> I have also heard that someone once measured the
> output power of their transmitter by connecting a
> regular power sensor in place of the antenna, and they
> measured 200 or 250 mW, but I don't think that is the
> proper way to measure it. A standard power sensor
> usually has a 50 ohm impedance, which may not be
> anything close to the actual impedance of a whip
> antenna, so they won't be measuring the actual power
> from the output stage.
>
> Gain? I have no clue. Gain is relative to an isotropic
> radiator (radiates equally in all directions) which is
> theoretical based on the power delivered to the
> antenna. The only way an antenna can have gain is if
> it radiates more in one (or more) directions more than
> in others. Think of an isotropic radiator as a light
> bulb, and an antenna with gain as a light bulb placed
> in a reflector. The more focused the beam, the higher
> the gain, but less light will be radiated outside the
> beam (lobe). For our purposes, we don't want a high
> gain antenna, since we could end up with a null signal
> in some directions.
>
> The best way to figure the gain (if any) of our
> systems would be to make EIRP or EDRP measurements
> (Effective Isotropic or Dipole Radiated Power) with a
> field measurement system, correlated to a calibrated
> antenna. I've done this for cell phones and wireless
> devices, but never one of our transmitters. (Never had
> the time). IMHO, it might not be a very repeatable or
> meaningful test since, in normal use, we will be
> holding the radio at ??? angle to the ground. Who
> wants to stand still on a turntable holding a
> transmitter for the time it would take to make the
> measurements at all different angles? :-) You could
> place the radio on a table, but that would not be real
> world.
>
> Polarization? Depends some on the angle the antenna is
> held, though I suspect it might be mostly vertical.
>
> I'm curious why they want all of this information? I
> would think they would only need to know the
> frequency, bandwidth, and radiated power.
>
> Bob R.
>
>
>
> --- Bill Glaze <billglaze at triad.rr.com> wrote:
> > I can answer a few:
> > Transmitter power:  1 watt maximum.  Actual, really
> > about 200 milliwatts
> > Transmitter radius is difficult, because you need to
> > have an effective
> > Field Strength Meter, but I have successfully
> > operated an airplane's
> > controls at 1.1 miles, (line of sight) but I didn't
> > intend to fly; I
> > couldn't even have seen the airplane.
> > Antenna used: Vertical Whip (Normally; that's what's
> > supplied)
> > Antenna gain; I don't really know the answer to that
> > one.
> > Polarization:  Vertical  (which is normal form a
> > whip antenna.)
> >
> > bravo52 wrote:
> >
> > > Hey Guys,
> > >   I am working on a project to get RC on my Air
> > Force Base and they
> > > have a few questions........  Can anybody answer
> > these questions for
> > > me given a standard Futaba or JR radio?
> > >
> > > 1. What is the transmitter power?
> > > 2. What is the radius the transmitter will operate
> > effectively?
> > > Consider miles not Line-of-sight. (I guess that
> > depends on #1)
> > > 3.  What type of transmit antenna will be used,
> > e.g., parabolic, whip,
> > > telescoping single pole, ect?
> > > 4.  What is the transmitter antenna gain?
> > > 5.  How is the transmit antenna polarized, e.g.,
> > horizontal, vertical,
> > > etc.?
> > >
> > > TAI
> > > v/r
> > > Jerry L.
> > >
> > > P.S. I tried to call Tony at RS but he left
> > > early...............hmmm.......was he at the
> > field????
> >
> >
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