On Mon, 25 Sep 2006 20:02:11 -0000, Dave Platt
wrote:
The elevation pattern of the antenna shows a hint of the high-angle
secondary lobes which characterize an EDZ.

This is definitely noticable on a log plot.

So, I'd conclude that you've developed a variant on the EDZ (or
something partway between an EDZ and a center-fed fullwave) which
yields slightly lower gain than an EDZ but has a simpler matching
section.

What sort of gain is expected from an EDZ? I tweaked the topology
of my design a bit in the hope of getting a broader bandwidth, but
instead got even more gain. For example, the version represented
below has a minimum gain of more than 4.7 dBi (at the side) and more
than 5.25 dBi in the forward direction. Previously I reported gain
values that ran from 4.2-4.7 dBi. So this one represents a bit of an
improvement. I may try building it this weekend. Thanks, --John

CM Model: expt5
CM parms = [4.68255, 3.41606, 36.4806, 7.22131, 11.9807, 3.02775, ];
CM
CM A1: 4-11/16 in.
CM A2: 3-7/16 in.
CM B1: 36-1/2 in.
CM B2: 7-1/4 in.
CM C: 12 in.
CM D: 3 in.
CM Wire diameter: 0.0640837
CM COM: (0 in., 9-1/16 in., 0 in.)
CM BBOX: dX=0, dY=11.9807, dZ=90.4316
CM COM Turning radius: 9.06615
CM Min Turning radius: 5.99035
CE
GW 1 3 0 0 9.10555 0 0 9.18245 0.000813863
GW 2 7 0 0 9.18245 0 0.30431 9.18245 0.000813863
GW 3 19 0 0.30431 9.18245 0 0.30431 10.1091 0.000813863
GW 4 5 0 0.30431 10.1091 0 0.30431 10.2925 0.000813863
GW 5 3 0 0.30431 10.2925 0 0.185373 10.2925 0.000813863
GW 6 3 0 0.30431 10.1091 0 0.217542 10.1091 0.000813863
GW 7 7 0 0 9.10555 0 0.30431 9.10555 0.000813863
GW 8 19 0 0.30431 9.10555 0 0.30431 8.17894 0.000813863
GW 9 5 0 0.30431 8.17894 0 0.30431 7.99552 0.000813863
GW 10 3 0 0.30431 7.99552 0 0.185373 7.99552 0.000813863
GW 11 3 0 0.30431 8.17894 0 0.217542 8.17894 0.000813863
GE 0
FR 0 201 0 0 144 0.02
EX 0 1 2 0 1
GN -1 0 0 0 0.0 0.0 0.0 0.0 0.0 0.0
RP 0 1 73 1001 90, 0, 1, 5
EN

In article ,
John E. Davis wrote:

The elevation pattern of the antenna shows a hint of the high-angle
secondary lobes which characterize an EDZ.

This is definitely noticable on a log plot.

So, I'd conclude that you've developed a variant on the EDZ (or
something partway between an EDZ and a center-fed fullwave) which
yields slightly lower gain than an EDZ but has a simpler matching
section.

What sort of gain is expected from an EDZ? I tweaked the topology
of my design a bit in the hope of getting a broader bandwidth, but
instead got even more gain. For example, the version represented
below has a minimum gain of more than 4.7 dBi (at the side) and more
than 5.25 dBi in the forward direction. Previously I reported gain
values that ran from 4.2-4.7 dBi. So this one represents a bit of an
improvement.

For an EDZ in isolation (no mast) I believe it's around 3 dBd or 5
dBi, plus or minus a hair.

I modelled a copper-pipe EDZ, mounted at the top end of a conductive
mast. This one came out with 5.85 dBi in the favored direction, and a
2.5 dB front-to-back ratio.

CEDouble extended zepp for 2 meters
GW 1 7 0 0 2 0 0 6.5 1.25 # Upper segment of mast
GW 2 7 0 0 2 0 0 -2 1.25 # Middle segment of mast
GW 3 100 0 0 -2 0 0 -112.5 1.25 # Lower segment of mast
GW 4 15 0 0 2 13 0 2 0.5 # Upper support bar
GW 5 15 0 0 -2 13 0 -2 0.5 # Lower support bar
GW 6 7 13 0 2 13 0 -2 0.5 # Shorting bar
GW 7 7 13 0 2 17 0 2 0.5 # To top of balun
GW 8 7 13 0 -2 17 0 -2 0.5 # To bottom of balun
GW 9 15 17 0 2 28 0 2 0.5 # To top arm
GW 10 15 17 0 -2 28 0 -2 0.5 # To bottom arm
GW 11 40 28 0 2 28 0 46 0.5 # Upper arm
GW 12 40 28 0 -46 28 0 -2 0.5 # Lower arm
GW 13 5 17 0 2 17 0 -2 0.5 # Feedline attachment
GS 0 0 0.0254
GE 0
EX 0 13 3 0 1.0
FR 0 1 0 0 145.27 0.00E+00 0.00E+00 0.00E+00 0.00E+00
0.00E+00
RP 0 61 72 1101 0.0 0.0 3 5
XQ
EN

A stacked pair of them on a single mast yields 8.85 dBi in the favored
direction, with 2.38 dB front-to-back ratio.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

On Wed, 27 Sep 2006 04:40:51 -0000, (Dave Platt) wrote:

In article ,
John E. Davis wrote:

The elevation pattern of the antenna shows a hint of the high-angle
secondary lobes which characterize an EDZ.

This is definitely noticable on a log plot.

So, I'd conclude that you've developed a variant on the EDZ (or
something partway between an EDZ and a center-fed fullwave) which
yields slightly lower gain than an EDZ but has a simpler matching
section.

What sort of gain is expected from an EDZ? I tweaked the topology
of my design a bit in the hope of getting a broader bandwidth, but
instead got even more gain. For example, the version represented
below has a minimum gain of more than 4.7 dBi (at the side) and more
than 5.25 dBi in the forward direction. Previously I reported gain
values that ran from 4.2-4.7 dBi. So this one represents a bit of an
improvement.

For an EDZ in isolation (no mast) I believe it's around 3 dBd or 5
dBi, plus or minus a hair.

I modelled a copper-pipe EDZ, mounted at the top end of a conductive
mast. This one came out with 5.85 dBi in the favored direction, and a
2.5 dB front-to-back ratio.

Have I missed something here? As I understand the EDZ (is it not the Extended
Double Zepp?) it comprises a center-fed doublet with a 5/8 wl wire on each side
of the feed point. It's broadside gain is about 3.1 dBd, with a narrower lobe
than that of a dipole, from which the gain over a dipole is obtained. Am I
correct so far?

If so, then we have only a single radiator. How then can there be a
front-to-back ratio?

Walt,W2DU

In article ,
Walter Maxwell wrote:

For an EDZ in isolation (no mast) I believe it's around 3 dBd or 5
dBi, plus or minus a hair.

I modelled a copper-pipe EDZ, mounted at the top end of a conductive
mast. This one came out with 5.85 dBi in the favored direction, and a
2.5 dB front-to-back ratio.

Have I missed something here? As I understand the EDZ (is it not the Extended
Double Zepp?) it comprises a center-fed doublet with a 5/8 wl wire on each side
of the feed point. It's broadside gain is about 3.1 dBd, with a narrower lobe
than that of a dipole, from which the gain over a dipole is obtained. Am I
correct so far?

Yup.

If so, then we have only a single radiator. How then can there be a
front-to-back ratio?

The model I developed/posted was for an EDZ, which is side-mounted at
the top of a conductive mast. One half of the doublet sticks up above
the mast "in the clear", but the other half runs down parallel to the
mast, perhaps a foot away.

As with any side- or tower-mounted antenna, there's some amount of
reflection from the mast, and this is enough to create a few dB of
"front to back" ratio.

If the antenna were modelled (or used) in isolation, with no mast and
with the feedline running out sideways, the "front to back" ratio
would be unity or very close to it. Just delete the mast pipe from
the model I posted and re-run NEC.

The design/installation data for Telewave's side-mounted folded-dipole
arrays show several different patterns, ranging from something very
close to a cardioid, to an "off-center circular" pattern, to a nearly
perfect circular pattern. All of these patterns can be achieved using
the same antenna array, by simply altering the length of the
side-mount arms which support the dipoles beside the mast or tower.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

On Wed, 27 Sep 2006 04:40:51 -0000, Dave Platt
wrote:
I modelled a copper-pipe EDZ, mounted at the top end of a conductive
mast. This one came out with 5.85 dBi in the favored direction, and a
2.5 dB front-to-back ratio.

Have you considered using the much simpler moxon? This one has a
forward gain of 5.6-6.4dBi (6.2@146MHz) and a front-to-back ratio of
18-31dBi (29@146MHz). It uses #12 AWG wire. Thanks, --John

CM Model: moxon for 2m
CM parms = [29.1337, 4.18345, 1.4995, 5.70003, ];
CM
CM A: 29-1/8 in.
CM B: 4-3/16 in.
CM C: 1-1/2 in.
CM D: 5-11/16 in.
CM Wire Diameter: 0.0808081
CE
GW 1 3 -0.10626 0 8.774 0 0 8.774 0.00102626
GW 2 15 0 0 8.774 0 0 9.514 0.00102626
GW 3 3 0 0 9.514 -0.10626 0 9.514 0.00102626
GW 4 3 -0.144347 0 9.514 -0.289128 0 9.514 0.00102626
GW 5 15 -0.289128 0 9.514 -0.289128 0 8.774 0.00102626
GW 6 3 -0.289128 0 8.774 -0.144347 0 8.774 0.00102626
GE 0
FR 0 401 0 0 144 0.01
EX 0 2 8 0 1
GN -1 0 0 0 0.0 0.0 0.0 0.0 0.0 0.0
RP 0 1 73 1001 90 0 1 5
EN

In article ,
John E. Davis wrote:

I modelled a copper-pipe EDZ, mounted at the top end of a conductive
mast. This one came out with 5.85 dBi in the favored direction, and a
2.5 dB front-to-back ratio.

Have you considered using the much simpler moxon? This one has a
forward gain of 5.6-6.4dBi (6.2@146MHz) and a front-to-back ratio of
18-31dBi (29@146MHz). It uses #12 AWG wire. Thanks, --John

If I were actually seeking a high front-to-back ratio, a Moxon would
be a good choice!

I actually developed the EDZ models for a different application... the
main antenna on a 2-meter repeater installation. We want a reasonable
amount of gain, and a near-omnidirectional pattern. The high
front-to-back ratio of a Moxon would not be appropriate in this case...
the 2.5 dB ratio of the side-mounted EDZ is probably as much as we'd
want to accept, given the shape and size of our service area.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

On 27 Sep 2006 02:49:55 GMT, I wrote wrote:
What sort of gain is expected from an EDZ? I tweaked the topology
of my design a bit in the hope of getting a broader bandwidth, but
instead got even more gain. For example, the version represented
below has a minimum gain of more than 4.7 dBi (at the side) and more
than 5.25 dBi in the forward direction. Previously I reported gain
values that ran from 4.2-4.7 dBi. So this one represents a bit of an
improvement. I may try building it this weekend. Thanks, --John

I found time this weekend to construct this antenna and it seems to
work quite well. See http://www.jedsoft.org/fun/antennas/omni.html
for the details including a picture of the antenna.

While testing it, I made a contact through a distant repeater (40
miles away) and was told that the signal was solid. This was with the
antenna in its test position with the center about 10 feet off the
ground and the transmitter power at 5 watts. Unfortunately I cannot
be more quantitation than that.

Unless I have overlooked some other design, this seems to be an
extremely simple and effective home-brew antenna.

Comments welcome.
Thanks,
--John