diversity reception notes
 

I must be doing something wrong.

Frequency 6.486MHz (BTW arabic male)

I first tried 2 active dipoles seperated by 100' on a north to south
line.
Next I tried a 50' wire 6' off the ground with a WinRadio WR-LWA-0130
"long
wire adpator, with either of the active dipoles, then I ran another 50'
at right
angles for the first, also with a WR-LWA-0130 and tried them all with
my
Mini Circuits ZFSC-2-1, that while rated for 5~1000MHz operation has
been
tested and it works fine down to well below 100KHz.

The nulls we less frequent but much deeper when they came.

I then used a 2nd R2000 and fed each receiver with different antennas
and just let
the audio "mix" from the respective speaker outputs. The active dipoles
gave the
best overall effect. There was a very pronounced comb filter effect
kind of like
The Small Faces "Itchycoo Park" from 1967, or Gobi Grant's "The
Westward Wind".

Not too bad I think I will investigate some more this weekend.

At this point a couple of active dipoles into a broadband "phaser"
allow me
to peak the signal and that works better the diveristy. Now what would
happen if I had 2 sets of active dipoles feeding seperate phasers
feeding
seperate receivers?

I can get at the AGC in my R2000 fairly easily and it should be fairly
simple
to build a comparator to pass the strongest signal to the audio chain.

Just what I need another radio project.

Terry

diversity reception notes
 

In article . com,
wrote:

I must be doing something wrong.

Frequency 6.486MHz (BTW arabic male)

I first tried 2 active dipoles seperated by 100' on a north to south
line. Next I tried a 50' wire 6' off the ground with a WinRadio
WR-LWA-0130 "long wire adpator, with either of the active dipoles,
then I ran another 50' at right angles for the first, also with a
WR-LWA-0130 and tried them all with my Mini Circuits ZFSC-2-1, that
while rated for 5~1000MHz operation has been tested and it works fine
down to well below 100KHz.

The nulls we less frequent but much deeper when they came.

I then used a 2nd R2000 and fed each receiver with different antennas
and just let the audio "mix" from the respective speaker outputs. The
active dipoles gave the best overall effect. There was a very
pronounced comb filter effect kind of like The Small Faces "Itchycoo
Park" from 1967, or Gobi Grant's "The Westward Wind".

Not too bad I think I will investigate some more this weekend.

At this point a couple of active dipoles into a broadband "phaser"
allow me to peak the signal and that works better the diveristy. Now
what would happen if I had 2 sets of active dipoles feeding seperate
phasers feeding seperate receivers?

I can get at the AGC in my R2000 fairly easily and it should be
fairly simple to build a comparator to pass the strongest signal to
the audio chain.

Just what I need another radio project.

For diversity reception you "switch" to the best signal instead of
mixing them together.

The best approach is two antennas with plus 1 wavelength between them
into two separate receivers and switch the audio between them based on a
decision circuit looking at both radios AGC voltage.

--
Telamon
Ventura, California

diversity reception notes
 

wrote:
I must be doing something wrong.

Frequency 6.486MHz (BTW arabic male)

I first tried 2 active dipoles seperated by 100' on a north to south
line.
Next I tried a 50' wire 6' off the ground with a WinRadio WR-LWA-0130
"long
wire adpator, with either of the active dipoles, then I ran another 50'
at right
angles for the first, also with a WR-LWA-0130 and tried them all with
my
Mini Circuits ZFSC-2-1, that while rated for 5~1000MHz operation has
been
tested and it works fine down to well below 100KHz.

The nulls we less frequent but much deeper when they came.

I then used a 2nd R2000 and fed each receiver with different antennas
and just let
the audio "mix" from the respective speaker outputs. The active dipoles
gave the
best overall effect. There was a very pronounced comb filter effect
kind of like
The Small Faces "Itchycoo Park" from 1967, or Gobi Grant's "The
Westward Wind".

Not too bad I think I will investigate some more this weekend.

At this point a couple of active dipoles into a broadband "phaser"
allow me
to peak the signal and that works better the diveristy. Now what would
happen if I had 2 sets of active dipoles feeding seperate phasers
feeding
seperate receivers?

I can get at the AGC in my R2000 fairly easily and it should be fairly
simple
to build a comparator to pass the strongest signal to the audio chain.

Just what I need another radio project.

Terry

Hi,

I would recommend reading the diversity section of "Communications
Receivers: DPS, Software Radios, and Design, 3rd Edition" by Ulrich
Rohde, Jerry Whitaker.

Generally speaking, mixing the inputs is helpful but not as good as
actively switching in the stronger signal.

This is somewhat more complex unless you have two receivers.

diversity reception notes
 

wrote:

Hi,

I would recommend reading the diversity section of "Communications
Receivers: DPS, Software Radios, and Design, 3rd Edition" by Ulrich
Rohde, Jerry Whitaker.

Generally speaking, mixing the inputs is helpful but not as good as
actively switching in the stronger signal.

This is somewhat more complex unless you have two receivers.



The 2 receivers part is not an issue. The one thing I have more then
enough of
is receivers. To do this right I will have to tap the AGC off both
receivers, feed
a comparator and use the comparator to select the strongest signal.

This was basicly an attempt to follow up on some comments by D Peter
Maus
about a "simple" diversity setup he had once that used multiple
antennas feeding
one receiver.

D Peter Maus' discription from another thread:
"Each antenna was connected to an RF preamp with a gain of 2-6db.
The outputs of the preamps were combined through resistive pads (for
isolation) into the RF input of the BC-794. The result was nothing
short of amazing, with fading distortions dramatically reduced, and
program listening, was quite pleasant. Even my wife was no longer
critical of SW listening."

My Mini Circuits ZFSC-2-1 has been tested and found to have better
then 25dB isolation from 250KHZ to above 30MHz., with less then 3.5dB
loss so I could dispense with the preamps. It only "cost" me an couple

of hours and I was able to listen during the test. The only time
"wasted"
was the few minutes spent spooling out my field antennas and pushing
a ground rod 4' in the ground. Not the best gorund, but good enough
for
some quick tests.

It is clear the idea has merrit, but it is also clear that to be
effective and
more then a toy some serious design work will be needed. Since I
already
have too many projects under way, this one will go in the big dream
book
of ideas that I hope to pursue when I retire.

Terry

diversity reception notes
 

Telamon wrote:

For diversity reception you "switch" to the best signal instead of
mixing them together.

The best approach is two antennas with plus 1 wavelength between them
into two separate receivers and switch the audio between them based on a
decision circuit looking at both radios AGC voltage.

--
Telamon
Ventura, California

http://www.radioblvd.com/DiversityDD1.html

I find the: "At first the engineers speculated that radio waves were
being refracted
in the ionosphere at different angles and therefore some waves would be
intercepted
by an antenna while other wave-angles would miss the antenna. A large
multiple
antenna should capture more wave angles and reduce fading. Actually,
they found
the opposite happened. Fading became worse with larger antenna arrays.
"
to agree with my experience in the much shorter active dipoles (~3' per
leg) worked
much better then the 50' wire antennas.

Terry

diversity reception notes
 

In article . com,
wrote:

Telamon wrote:

For diversity reception you "switch" to the best signal instead of
mixing them together.

The best approach is two antennas with plus 1 wavelength between
them into two separate receivers and switch the audio between them
based on a decision circuit looking at both radios AGC voltage.

http://www.radioblvd.com/DiversityDD1.html

I find the: "At first the engineers speculated that radio waves were
being refracted in the ionosphere at different angles and therefore
some waves would be intercepted by an antenna while other wave-angles
would miss the antenna. A large multiple antenna should capture more
wave angles and reduce fading. Actually, they found the opposite
happened. Fading became worse with larger antenna arrays. " to agree
with my experience in the much shorter active dipoles (~3' per leg)
worked much better then the 50' wire antennas.

Yes, if you sum the output of several antennas on over the horizon
signals you could end up with greater fading.

One antenna with a greater cross sectional area should have less fading
than say a small amplified antenna.

Diversity reception can also be achieved with two antennas in the same
location with one having vertical and the other horizontal polarization.

--
Telamon
Ventura, California