Transmitter power questions.....

Tue Apr 12 02:00:42 AKDT 2005

Jerry,

Just an FYI, Selfridge ANG Base in Michigan, uses RC planes to chase birds 
off of their runways, so they are allowed in some cases. I have been 
approached by a guy that works on base, as a civilian, about coming and 
flying for them.  The only hitch is, for now, you have to use their planes 
and transmitters, you can's bring your own.

Ken
----- Original Message ----- 
From: "bravo52" <bravo52 at cox-internet.com>
To: <discussion at nsrca.org>
Sent: Monday, April 11, 2005 11:10 PM
Subject: Re: Transmitter power questions.....

> 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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