I have checked a few references, but I would really like
to 'hear from experienced ears', soooo, the question.
If you setup two situations alike, such as two same autos, same
amount of power, same db gain on mobil/base antennas , what would be
the difference in the 'distance of one band over the other'. If two
meters 'talked' farther,,,,,,,,,,,, than 440mhz. what would likely be
the amount.
I live 'out in the boonies', and thru the base antenna 'reach out'
and connect with the cities repeaters, and I '''see/hear''' very
little difference in the range (those located close to each other) of
such repeaters, (two meters/440). This along with other factors has
lead to this question.
In the past, the 'minor tests' that I have conducted did not really
prove that much. I, at home/base talking to my yl and switching
between 'bands', this was not all that scientific, and all I concluded
was 'the bands' were similar in abilities. ???? Sooo, feel that others
have 'been there,done that',,,,, and had more in lighten results.
thanks in advance. 73 cl.

Take a look at this one:
http://www.artscipub.com/simpleton/simp.range.html
--
73 From The Wilderness Keyboard
wrote in message
...
I have checked a few references, but I would really like
to 'hear from experienced ears', soooo, the question.
If you setup two situations alike, such as two same autos, same
amount of power, same db gain on mobil/base antennas , what would be
the difference in the 'distance of one band over the other'. If two
meters 'talked' farther,,,,,,,,,,,, than 440mhz. what would likely be
the amount.
I live 'out in the boonies', and thru the base antenna 'reach out'
and connect with the cities repeaters, and I '''see/hear''' very
little difference in the range (those located close to each other) of
such repeaters, (two meters/440). This along with other factors has
lead to this question.
In the past, the 'minor tests' that I have conducted did not really
prove that much. I, at home/base talking to my yl and switching
between 'bands', this was not all that scientific, and all I concluded
was 'the bands' were similar in abilities. ???? Sooo, feel that others
have 'been there,done that',,,,, and had more in lighten results.
thanks in advance. 73 cl.

Hello,

Out in the open, with no obstructions there will be little difference. The
only good thing about UHF is high gain antennas that are a lot smaller, so
that can help. For hills and mountains you would be better on 70MHz, it
does tend to cover an area better than 2m. In a town centre go for 70cm.
Not knowing where you are it's difficult to advise. Repeaters are so high
anyway it wouldn't be noticable.

"Keyboard In The Wilderness" wrote in message
news:I9LCb.11937$m83.3296@fed1read01...
Take a look at this one:
http://www.artscipub.com/simpleton/simp.range.html
--
73 From The Wilderness Keyboard
wrote in message
...
I have checked a few references, but I would really like
to 'hear from experienced ears', soooo, the question.
If you setup two situations alike, such as two same autos, same
amount of power, same db gain on mobil/base antennas , what would be
the difference in the 'distance of one band over the other'. If two
meters 'talked' farther,,,,,,,,,,,, than 440mhz. what would likely be
the amount.
I live 'out in the boonies', and thru the base antenna 'reach out'
and connect with the cities repeaters, and I '''see/hear''' very
little difference in the range (those located close to each other) of
such repeaters, (two meters/440). This along with other factors has
lead to this question.
In the past, the 'minor tests' that I have conducted did not really
prove that much. I, at home/base talking to my yl and switching
between 'bands', this was not all that scientific, and all I concluded
was 'the bands' were similar in abilities. ???? Sooo, feel that others
have 'been there,done that',,,,, and had more in lighten results.
thanks in advance. 73 cl.

Chuck:

The basic equation for path attenuation is Attn. = 36.6 + 20 log F(MHz) + 20
log d (miles) (in dB).*

The log function dilutes the effect of frequency change, so tripling the
frequency from 147 MHz to 441 MHz increases the loss by 20 log 3 ~ 10 dB.
If the UHF antenna gain is increased by 5 dB on each end it is a wash. A 20
foot long DB-224 antenna has 6 dB of gain on 144, and a 20 foot long DB-410
has 10 dB of gain on 440, so the overall loss going from VHF to UHF with
comparative size antennas is about 2 dB. Not really noticeable except under
marginal conditions. Mobile antennas on VHF run from unity to 3 dB, and UHF
run from unity to 6 dB, so the system loss difference for base to mobile can
be from 3 dB to 5 dB, which approaches noticeable, but not remarkable.
Distance difference will be in the same category, hard to notice. UHF tends
to diffract better, so it will go "over the hill" a little further. while
VHF will go a little further on flat ground. There is no one exact answer
for which works better. Give me an exact path description and I can
calculate loss, but paths of the same length with different profiles will
vary greatly.

Another rule of thumb is doubling antenna elevation at VHF produces about 6
dB gain, so my antenna on top of my monster truck roof will work 6 dB better
than the one on your motorcycle.

That what you are looking for?

* ITT Handbook, Chapter 28 in most recent editions.
--
Crazy George
Remove N O and S P A M imbedded in return address

KC5CQA wrote:
"In the past, the minor tests that I have conducted did not really prove
that much."

That might imply that there isn`t much to prove. You might infer that
VHF and UHF transmission ranges are similar.

One fact is that communication is a case of signal versus noise. Path
attenuation acts on both signal and noise. At UHF, signals may be
weaker, but noise is weaker too.

Harmonics of strong signals some times compete with the signal you
would like to receive. The 5th harmonic production is usually
inherently weaker than the 3rd, etc. This can make UHF signals usable in
some cases when VHF signals are not.

UHF may be reflected or blocked by smaller obstacles then VHF, but UHF
also penetrates and propagates through smaller spaces.

Antenna gain is more feasible at UHF.

Consider TV coverage, UHF channels versus VHF channels. The difference
in coverage is small..

In the good old days, increasing the frequency often meant decreasing
equipment performance. Solutions have now been found to many UHF
equipment problems.

Best regards, Richard Harrison, KB5WZI

Consider TV coverage, UHF channels versus VHF channels. The difference
in coverage is small..

In the good old days, increasing the frequency often meant decreasing
equipment performance. Solutions have now been found to many UHF
equipment problems.

Best regards, Richard Harrison, KB5WZI


Not sure about the TV stations but I was thinking they can run more ERP than
the VHF stations.

In the 'good old days' it was difficult to build a receiver that was as
sensitive at 440 as it was at 150 mhz and power was harder to generate also.
With solid state there is very little differance in the devices sensitivity
up to atleast 1ghz and maybe higher than it is at 30 mhz. Power in the
range of 100 watts is easy in the solid state units also now.
For the last few years it seems that many ham rigs have about 35 watts on
440 and 50 watts on 2 meters. Mainly in solid state gain blocks. Not that
much differance .