Area 51 for Antenna Modelers & Builders (See Post #1) - Page 27 - Canadian TV, Computing and Home Theatre Forums

holl_ands · 2009-09-04, 02:00 PM

Vorg:

1. AutoGainTest was off by a couple dB in V1, V2 and V3, resulting in inflated Gain numbers.
To fix, change the SOURCE Radius to 0.114, 0.089 and 0.096 respectively.
AGT adjustment procedure was described in some earlier posts.

V1: UHF Raw Gain=3.2(470MHz)-4.2(650)-4.0(698)-1.4(806) dBi.
SWR(300ohm)=3.1(470MHz)-1.04(662)-1.3(698)-1.8(806).

V2: UHF Raw Gain=3.7(470MHz)-5.1(698)-5.2(735)-4.1(806) dBi.
SWR(300ohm)=2.0(470MHz)-1.3(698)-1.09(758)-1.4(806).

V3: UHF Raw Gain=2.7(470MHz)-5.0(662)-4.8(698)-1.5(806) dBi.
SWR(300ohm)=1.5(470MHz)-1.13(674)-1.2(698)-1.9(806).

Also note that when you "split the difference" and aim between the desired directions,
the gain at +/- 60-degrees from the X-Axis is NEGATIVE for nearly all freqs, rising
to just barely above 0 dBi at the highest freqs. So these aren't the best choice.

===================================
Trying to get a "normal" antenna to cover much more than 60-deg beamwidth is very hard.
Turnstile antennas are frequently used in FM Band for Omni coverage, which you will
recognize is either a pair of (0 dBd=2.1 dBi) Folded Dipoles or a single, Twisted Folded Dipole:
http://www.mindspring.com/~brucec/fmant.htm

BTW: I am philosphically against Omni antennas for the TV band due to the need to
SUPPRESS multipath coming in from (mostly) the rear of the antenna....Hence
the importance of Front/Back and Front/Rear Ratios.

holl_ands · 2009-09-04, 02:37 PM

HOVERMAN TYPE 1 OMNI-DIRECTIONAL:

BUT, if you are looking for more Gain, then some sort of "stacked" antenna is
needed to increase Gain by reducing the Elevation response.

One such antenna I was coincidentally working on analyzing is the Hoverman.
In D. R. Hoverman's US Patent 2,918,672, in addition to the much studied Type 1
(NO Reflector) version was an Omni-Directional variant I analyzed here:
http://imageevent.com/holl_ands/grayhoverman

The bottom half is twisted 90-degrees, resulting in an azimuthal response that
looks like two back-to-back Kidneys. For stations separated at 120-deg,
the Hoverman Type 1 Omni would be pointed so that the "lump" at 105-deg points
to one location and the "lump" at 345-deg points to the other. I adjusted the
Lateral "Spurs" at the top and bottom of the antenna down to 5.5-in for best
performance toward these directions.

Moving the end Zig-Zag segments outward (i.e. "Spurs") is the first mod that D. R.
Hoverman did to a Chireix antenna. The second was to make it 30-percent SMALLER,
cuz the Gain curve was not only more broadband, but also shifted in frequency.
Per the Patent, Hoverman stipulated the Spurs to be the same length as all of the
other elements (7.0-in). But I found that 6.25-in was a better fit for (non-twisted)
Type 1 in the New UHF Band.

The Type 1 Omni Hoverman (Spur=5.5-in for better high freq performance) has an
increasing Gain curve as follows:
UHF Raw Gain Max=0.7(470MHz)-4.5(650)-3.7(698) dBi
(Same for 105, 165, 285 & 345-deg).

Type 1 Omni Hoverman 4nec2 File, Diagram, Azimuthal Response Patterns and Gain Curve:
http://photos.imageevent.com/holl_an...SY.nec.doc.pdf
http://photos.imageevent.com/holl_an...03D%20View.jpg
http://photos.imageevent.com/holl_an...20Patterns.jpg
http://photos.imageevent.com/holl_an...and345-deg.jpg

Others designers may have their own favorite super-widebeamwidth antenna,
hopefully one that doesn't have mediocre gain at low freqs.....

Or bite the bullet and use two high gain antennas that can overcome a 4 dB combiner loss.....

holl_ands · 2009-09-04, 05:04 PM

wildwillie:
I think X390 needs to be resegmented....only 1 seg for a wide range of lengths in feedline
and only 11 seg in the long reflector rods. After Resegment within GeoEdit and adjust
AGT=1.0, I get Max Gain =17.4 dBi at 626 MHz....and a second 17.2 dBi hump at 592 MHz.
But SWR(300) climbs to 5.2 mid-band....and SWR(150) climbs to 4.7 at 662 MHz.

Resegmenting fixed most Warnings. Now I only see two "Notes" re unequal
segmentation in parallel wires (tags 78/90 and tags 80/92)....which are tolerated.
I'm not sure why, but 1/2-in Gap sizes usually cause problems in 4nec2 for UHF.....
Which is why I usually use 0.75-in, based on parameter sweeps in other antennas.....

PS: Now it takes nearly an hour to run a simple freq response plot...w/o azimuth pattern.

wildwillie · 2009-09-04, 05:41 PM

thanks for the help and knownledge holl_ands.

After installing the card i need to see the AGT resaults , I was suprized to see the out comes for the SWR . I will have to make ajustments to the feed line gap as mentioned.

I'm still trying to understand why at 70 mhz frequence and at 170 that the gain and SWR are different. I'm still learning .

again holl_ands and 300ohms and others thank you you all for sharing your knownlodge

300ohm · 2009-09-04, 05:51 PM

Quote:

version was an Omni-Directional variant I analyzed here:

Good job, holl_ands.

Autofils did a quick study of it a long time ago, and it showed the omni version was pretty poor. Stacking it may give 2.5 dbi more, which may be enough for city/near suburban dwellers surrounded by antenna farms.

wildwillie · 2009-09-04, 09:39 PM

holl_ands nice work on the GH.

I was tring to just make a wide pattern
my X396

Code:

CM x396
CM by wildwillie 
CE
GW	1	3	-0.5	0	-4.5	-2	0	-4.5	0.14464842
GW	2	3	-2	0	-4.5	-2	0	-3.5	0.14464842
GW	3	3	-0.5	0	-4.5	-0.5	0	-3.5	0.14464842
GW	4	5	-0.5	0	-3.5	1.5	0	-3.5	0.16243037
GW	5	5	-2	0	-3.5	-4.5	0	-3.5	0.14464842
GW	9	13	1.5	0	-3.5	7.5	0	-3.5	0.16243037
GW	11	3	-4.5	0	-3.5	-5.5	0	-3.5	0.14464842
GW	12	23	7.5	0	-3.5	7.5	0	7.5	0.14464842
GW	13	19	1.5	0	-3.5	1.5	0	6	0.14464842
GW	14	23	-5.5	0	-3.5	-5.5	0	7.5	0.14464842
GW	15	19	-4.5	0	-3.5	-4.5	0	6	0.14464842
GW	16	17	7.5	0	-3.5	16	0	-3.5	0.14464842
GW	17	15	16	0	-3.5	16	0	3.5	0.16243037
GW	18	5	16	0	-3.5	18.5	0	-3.5	0.14464842
GW	19	17	18.5	0	-3.5	18.5	0	5	0.14464842
GS	0	0	0.0254		' All in in.
GE	0
EK
LD	5	0	0	0	5.8e7	0
EX	0	1	2	0	1	0
GN	-1
FR	0	1	0	0	470	0

Vorg · 2009-09-04, 10:29 PM

holl_ands, thanks for the information. I'll try to look at it over the next few days. The Square loop using #14 wire works well enough in one room where if turned right, all channels are will in the "good" on an Insignia box, but in the room where it gets used the most, where the vdr setup is, it can hardly get enough signal for a picture on the best channel. So it will have to be roof mounted.

The reason it needs to be omni, is the 3 directions combined with it is to be connected to a linux computer with a dual atsc and a single atsc tuner card so that it can record up to 3 channels at the same time. They always like to put shows on at near the same time and you have to allow overlap when using timers. And this setup monitors the epg for shows and sets up the timers as the come up in the guide, then put the recordings into folder by show for series shows. We can then watch them when we want. Sort of a custom built tvio. VDR does have plugins for dish rotors, sat switches but no support for antenna rotors and there no electronicly controlled switches for OTA which would do any good anyway as the dual tuner only has 1 input. So the antenna needs to be able to supply all the stations down the same cable.

I was thinking about using high gain antennas at first. But the common thought was wouldn't work well. Needing 3 directions makes it harder because a bi-directional can still only aim at one at a cost of gain to the other. And there is the phase differance of 2-3 antennas.

300ohm · 2009-09-05, 07:28 AM

Quote:

The reason it needs to be omni, is the 3 directions combined with it is to be connected to a linux computer with a dual atsc and a single atsc tuner card so that it can record up to 3 channels at the same time.

Look at mlord's thread about switching antennas electromechcanically for his linux mythTV setup. Thats about the only way to do it automatically if you need high gain in all three directions.

Quote:

because a bi-directional can still only aim at one at a cost of gain to the other.

No, on a bidirectional, the gain is the same in both directions. A reflectorless DBGH can get you 13 - 14 dbi in two directions. The beamwidth may be wide enough to suit your needs for 2 of the 3 directions. (if not, a small angular change of the SBGHs of the DBGH may do it, at a small cost of dbi depending on the angle change) The third direction could be handled by another antenna into an A-B switch at the TV. (I would make the 3rd antenna the highest gain one, with reflector, and aim it in the weakest direction)

300ohm · 2009-09-05, 09:31 AM

Looks like the straight NAROD reflector can be used with the Top Hat NAROD just fine, producing only the tiniest dip (.2 dbi tops) at 575 mhz.

Code:

CM SBGH gen 1 - Length of each diagonal sub-section = 7.07 inches 
CM Gap at feedpont = 3.5 inches
CM Stub length = 5.6 inches
CM 9 gauge wire
CM Top Hat NAROD with Straight NAROD reflector
CM No uhf reflectors
CE
GW	2	10	0	1.75	0	0	6.7488189	5	0.05721178
GW	3	10	0	6.7488189	5	0	1.75	10	0.05721178
GW	4	10	0	1.75	10	0	6.7488189	15	0.05721178
GW	5	5	0	6.7488189	15	0	12.3488189	15	0.05721178
GW	6	10	0	1.75	0	0	6.7488189	-5	0.05721178
GW	7	10	0	6.7488189	-5	0	1.75	-10	0.05721178
GW	8	10	0	1.75	-10	0	6.7488189	-15	0.05721178
GW	9	5	0	6.7488189	-15	0	12.3488189	-15	0.05721178
GW	10	10	0	-1.75	0	0	-6.7488188	5	0.05721178
GW	11	10	0	-6.7488188	5	0	-1.75	10	0.05721178
GW	12	7	0	-1.75	10	0	-6.748819	15	0.05721178
GW	13	5	0	-6.748819	15	0	-12.348819	15	0.05721178
GW	14	10	0	-1.75	0	0	-6.7488188	-5	0.05721178
GW	15	10	0	-6.7488188	-5	0	-1.75	-10	0.05721178
GW	16	7	0	-1.75	-10	0	-6.748819	-15	0.05721178
GW	17	5	0	-6.748819	-15	0	-12.348819	-15	0.05721178
GW	18	5	0	-1.75	0	0	1.75	0	0.03598084
GW	100	7	0	0	17.5	0	9.5	17.5	0.05721178
GW	101	1	0	9.5	17.5	0	9.75	17.25	0.05721178
GW	102	1	0	9.75	17.25	0	9.75	16.75	0.05721178
GW	103	1	0	9.75	16.75	0	9.5	16.5	0.05721178
GW	104	1	0	9.5	16.5	0	8	16.5	0.05721178
GW	105	1	0	8	16.5	0	7.75	16.25	0.05721178
GW	106	1	0	7.75	16.25	0	7.75	15.75	0.05721178
GW	107	1	0	7.75	15.75	0	8	15.5	0.05721178
GW	108	3	0	12.125	15.5	0	8	15.5	0.05721178
GW	109	7	0	0	17.5	0	-9.5	17.5	0.05721178
GW	110	1	0	-9.5	17.5	0	-9.75	17.25	0.05721178
GW	111	1	0	-9.75	17.25	0	-9.75	16.75	0.05721178
GW	112	1	0	-9.75	16.75	0	-9.5	16.5	0.05721178
GW	113	1	0	-9.5	16.5	0	-8	16.5	0.05721178
GW	114	1	0	-8	16.5	0	-7.75	16.25	0.05721178
GW	115	1	0	-7.75	16.25	0	-7.75	15.87	0.05721178
GW	116	1	0	-7.75	15.87	0	-8	15.5	0.05721178
GW	117	3	0	-8	15.5	0	-12.125	15.5	0.05721178
GW	118	7	0	0	-17.5	0	9.5	-17.5	0.05721178
GW	119	1	0	9.5	-17.5	0	9.75	-17.25	0.05721178
GW	120	1	0	9.75	-17.25	0	9.75	-16.75	0.05721178
GW	121	1	0	9.75	-16.75	0	9.5	-16.5	0.05721178
GW	122	1	0	9.5	-16.5	0	8	-16.5	0.05721178
GW	123	1	0	8	-16.5	0	7.75	-16.25	0.05721178
GW	124	1	0	7.75	-16.25	0	7.75	-15.75	0.05721178
GW	125	1	0	7.75	-15.75	0	8	-15.5	0.05721178
GW	126	3	0	12.125	-15.5	0	8	-15.5	0.05721178
GW	127	7	0	0	-17.5	0	-9.5	-17.5	0.05721178
GW	128	1	0	-9.5	-17.5	0	-9.75	-17.25	0.05721178
GW	129	1	0	-9.75	-17.25	0	-9.75	-16.75	0.05721178
GW	130	1	0	-9.75	-16.75	0	-9.5	-16.5	0.05721178
GW	131	1	0	-9.5	-16.5	0	-8	-16.5	0.05721178
GW	132	1	0	-8	-16.5	0	-7.75	-16.25	0.05721178
GW	133	1	0	-7.75	-16.25	0	-7.75	-15.75	0.05721178
GW	134	1	0	-7.75	-15.75	0	-8	-15.5	0.05721178
GW	135	3	0	-8	-15.5	0	-12.125	-15.5	0.05721178
GW	136	25	-11.5	15.125	-15.5	-11.5	-15.125	-15.5	0.05721178
GW	137	25	-11.5	15.125	15.5	-11.5	-15.125	15.5	0.05721178
GS	0	0	0.0254		' All in in.
GE	0
EK
EX	0	18	3	0	1	0
GN	-1
FR	0	38	0	0	473	6
RP 0 1 10 1510 90. 0. 0. 20. 0. 0.
EN

holl_ands · 2009-09-05, 10:50 AM

Quote:

Originally Posted by wildwillie

I was trying to just make a wide pattern
my X396

Where have I seen something like your X396 "Fence" antenna before?????
Can you cite a reference or is it truly your invention????

Because the radiating elements are Vertical, X396 is mostly Vertically Polarized
(with a very wide beamwidth), BUT it only has a small amount of response to
Horizontally Polarized TV signals on the highest channels.

For H-Pol, it would need to be turned over on it's side, looking a lot like a Yagi
that someone chopped off all of the elements on one side.
Now the Azimuthal response is non-symmetrical and varies considerably
with frequency.....and although it has 5.2-6.5 dBi Gain, it isn't wide beamwidth:
http://imageevent.com/holl_ands/notfortv/fence

holl_ands · 2009-09-05, 11:37 AM

Vorg:
I've had the time to track down and look at your TVFool results. I originally
thought you had three tower groups ALL WITHIN a 120-deg span....not quite....

I now see that most of your towers are within a 139-deg arc (260 to 39-deg)
plus The CW (your strongest) at 171-deg. Because most antennas have a NULL
at 90-deg from the beam, they're always operating at reduced Gain on the
sidelobes. I wouldn't worry too much about The CW....it's strong enough to
come in on the BACK of most any antenna.

So for BEST performance OUTSIDE, I'm still recommending using two high
gain Hi-VHF/UHF antennas with a combiner....such as NAROD SBGHs or M4s.

You have a mix of UHF (39-deg, 260 & 275-deg), Hi-VHF (39-deg & 275-deg)....and
Ch4 K04QP-D (please say you can survive if it isn't picked up by a Hi-VHF antenna....)

=============================================
The Hoverman Type 1 Omni is still a candidate, although your beamwidth
spread is a little bit wider (139 vice 120-deg).
The NULL is along the same direction as the Balun wire connections. It would
be oriented so that it is directed about 15-deg AWAY from 171-deg (The CW),
choosing one side or the other, depending on whether you want to favor 39-deg
or 260/275-deg.

BTW: The Type 1 Omni has 3.3-3.9 dBi Raw Gain on Ch7-13, but with a very
high SWR (as is common when using UHF antennas for Hi-VHF).
I added Hi-VHF plots: http://imageevent.com/holl_ands/grayhoverman
So you have a good chance of also picking up Ch 9, 13 and maybe Ch7. And
if you DO have Hi-VHF reception problems, you could add a Hi-VHF Loop.

=================================================
But I would first try the UHF Square Loop----OUTSIDE. You have lots of strong signals
and are likely suffering from "Indoor Antenna Syndrome", which will probably clear up
by moving it OUTSIDE, where it can get plenty of sunshine.....but it won't have much
Gain on Hi-VHF channels....or Ch4. There may also be some "better" alternatives to
the Type 1 Omni Hoverman....

PS: But even with a big high gain antenna, those stations with significantly
negative "NM" just aren't in your future....

wildwillie · 2009-09-05, 11:47 AM

holl_ands , http://www.jedsoft.org/fun/antennas/omni/omni.html
I was tring to make that design work , for x396

holl_ands · 2009-09-05, 11:54 AM

I was thinking I saw it in an ARRL publication....maybe one of the Antenna Compendiums.....

Vorg · 2009-09-06, 03:29 AM

The CW in fact seems to be the weakest station. It is twice as far away as the others and somewhat down hill from us. The stations to the north are on mountains ~5800' above Tucson. The stations to the west are on more of a hill then a mountain.

The square 6.5" on a side loop I made from #14 wire, my dad tried at his place and could get all the digital channels (barely) except for CW which popped in and out, mostly out. But when he tried it on the roof, with a little aiming, he is getting all the channels fairly well, but with little leeway for signal changes. I will need a splitter on what I put on the roof. So Don't need mega gain, but need to fluff up the cushion.

I am mainly interested in the digital channels. I don't know what those analog ones are. Maybe spanish. Some of the ones listed as analog are in fact duplicate digital broadcast. Channel 13.x are on vhf 13 as well as a uhf channel. 9.x seem to be split, some are on vhf 9 and we now found some on uhf. Why I don't know since they only have 4 9.x channels and you can have up to 6. The linux vdr setup right now can only handle digital channels. The one with two cards, has an HVR-1800 which also can do analog but I never got the analog plugin for vdr working.

holl_ands · 2009-09-06, 09:57 AM

I was looking at post #104 in the Fractal thread:
http://www.digitalhome.ca/forum/showthread.php?p=957893
If you used your street address, you might find more believeable results using LAT/LOG,
such as from GoogleEarth.....or perhaps The CW's ERP is less than that assumed in TVFool.....

2009-09-06, 03:29 AM	#404
Vorg Join Date: Jul 2009 Posts: 71	The CW in fact seems to be the weakest station. It is twice as far away as the others and somewhat down hill from us. The stations to the north are on mountains ~5800' above Tucson. The stations to the west are on more of a hill then a mountain. The square 6.5" on a side loop I made from #14 wire, my dad tried at his place and could get all the digital channels (barely) except for CW which popped in and out, mostly out. But when he tried it on the roof, with a little aiming, he is getting all the channels fairly well, but with little leeway for signal changes. I will need a splitter on what I put on the roof. So Don't need mega gain, but need to fluff up the cushion. I am mainly interested in the digital channels. I don't know what those analog ones are. Maybe spanish. Some of the ones listed as analog are in fact duplicate digital broadcast. Channel 13.x are on vhf 13 as well as a uhf channel. 9.x seem to be split, some are on vhf 9 and we now found some on uhf. Why I don't know since they only have 4 9.x channels and you can have up to 6. The linux vdr setup right now can only handle digital channels. The one with two cards, has an HVR-1800 which also can do analog but I never got the analog plugin for vdr working. Last edited by Vorg; 2009-09-06 at 04:25 AM.

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2009-09-04, 02:00 PM	#391
holl_ands Veteran Join Date: Nov 2008 Location: San Diego, CA Posts: 1,600	Vorg: 1. AutoGainTest was off by a couple dB in V1, V2 and V3, resulting in inflated Gain numbers. To fix, change the SOURCE Radius to 0.114, 0.089 and 0.096 respectively. AGT adjustment procedure was described in some earlier posts. V1: UHF Raw Gain=3.2(470MHz)-4.2(650)-4.0(698)-1.4(806) dBi. SWR(300ohm)=3.1(470MHz)-1.04(662)-1.3(698)-1.8(806). V2: UHF Raw Gain=3.7(470MHz)-5.1(698)-5.2(735)-4.1(806) dBi. SWR(300ohm)=2.0(470MHz)-1.3(698)-1.09(758)-1.4(806). V3: UHF Raw Gain=2.7(470MHz)-5.0(662)-4.8(698)-1.5(806) dBi. SWR(300ohm)=1.5(470MHz)-1.13(674)-1.2(698)-1.9(806). Also note that when you "split the difference" and aim between the desired directions, the gain at +/- 60-degrees from the X-Axis is NEGATIVE for nearly all freqs, rising to just barely above 0 dBi at the highest freqs. So these aren't the best choice. =================================== Trying to get a "normal" antenna to cover much more than 60-deg beamwidth is very hard. Turnstile antennas are frequently used in FM Band for Omni coverage, which you will recognize is either a pair of (0 dBd=2.1 dBi) Folded Dipoles or a single, Twisted Folded Dipole: http://www.mindspring.com/~brucec/fmant.htm BTW: I am philosphically against Omni antennas for the TV band due to the need to SUPPRESS multipath coming in from (mostly) the rear of the antenna....Hence the importance of Front/Back and Front/Rear Ratios.

2009-09-04, 02:37 PM	#392
holl_ands Veteran Join Date: Nov 2008 Location: San Diego, CA Posts: 1,600	HOVERMAN TYPE 1 OMNI-DIRECTIONAL: BUT, if you are looking for more Gain, then some sort of "stacked" antenna is needed to increase Gain by reducing the Elevation response. One such antenna I was coincidentally working on analyzing is the Hoverman. In D. R. Hoverman's US Patent 2,918,672, in addition to the much studied Type 1 (NO Reflector) version was an Omni-Directional variant I analyzed here: http://imageevent.com/holl_ands/grayhoverman The bottom half is twisted 90-degrees, resulting in an azimuthal response that looks like two back-to-back Kidneys. For stations separated at 120-deg, the Hoverman Type 1 Omni would be pointed so that the "lump" at 105-deg points to one location and the "lump" at 345-deg points to the other. I adjusted the Lateral "Spurs" at the top and bottom of the antenna down to 5.5-in for best performance toward these directions. Moving the end Zig-Zag segments outward (i.e. "Spurs") is the first mod that D. R. Hoverman did to a Chireix antenna. The second was to make it 30-percent SMALLER, cuz the Gain curve was not only more broadband, but also shifted in frequency. Per the Patent, Hoverman stipulated the Spurs to be the same length as all of the other elements (7.0-in). But I found that 6.25-in was a better fit for (non-twisted) Type 1 in the New UHF Band. The Type 1 Omni Hoverman (Spur=5.5-in for better high freq performance) has an increasing Gain curve as follows: UHF Raw Gain Max=0.7(470MHz)-4.5(650)-3.7(698) dBi (Same for 105, 165, 285 & 345-deg). Type 1 Omni Hoverman 4nec2 File, Diagram, Azimuthal Response Patterns and Gain Curve: http://photos.imageevent.com/holl_an...SY.nec.doc.pdf http://photos.imageevent.com/holl_an...03D%20View.jpg http://photos.imageevent.com/holl_an...20Patterns.jpg http://photos.imageevent.com/holl_an...and345-deg.jpg Others designers may have their own favorite super-widebeamwidth antenna, hopefully one that doesn't have mediocre gain at low freqs..... Or bite the bullet and use two high gain antennas that can overcome a 4 dB combiner loss.....

2009-09-04, 05:04 PM	#393
holl_ands Veteran Join Date: Nov 2008 Location: San Diego, CA Posts: 1,600	wildwillie: I think X390 needs to be resegmented....only 1 seg for a wide range of lengths in feedline and only 11 seg in the long reflector rods. After Resegment within GeoEdit and adjust AGT=1.0, I get Max Gain =17.4 dBi at 626 MHz....and a second 17.2 dBi hump at 592 MHz. But SWR(300) climbs to 5.2 mid-band....and SWR(150) climbs to 4.7 at 662 MHz. Resegmenting fixed most Warnings. Now I only see two "Notes" re unequal segmentation in parallel wires (tags 78/90 and tags 80/92)....which are tolerated. I'm not sure why, but 1/2-in Gap sizes usually cause problems in 4nec2 for UHF..... Which is why I usually use 0.75-in, based on parameter sweeps in other antennas..... PS: Now it takes nearly an hour to run a simple freq response plot...w/o azimuth pattern.

2009-09-04, 05:41 PM	#394
wildwillie Join Date: Jan 2009 Posts: 280	thanks for the help and knownledge holl_ands. After installing the card i need to see the AGT resaults , I was suprized to see the out comes for the SWR . I will have to make ajustments to the feed line gap as mentioned. I'm still trying to understand why at 70 mhz frequence and at 170 that the gain and SWR are different. I'm still learning . again holl_ands and 300ohms and others thank you you all for sharing your knownlodge

2009-09-04, 10:29 PM	#397
Vorg Join Date: Jul 2009 Posts: 71	holl_ands, thanks for the information. I'll try to look at it over the next few days. The Square loop using #14 wire works well enough in one room where if turned right, all channels are will in the "good" on an Insignia box, but in the room where it gets used the most, where the vdr setup is, it can hardly get enough signal for a picture on the best channel. So it will have to be roof mounted. The reason it needs to be omni, is the 3 directions combined with it is to be connected to a linux computer with a dual atsc and a single atsc tuner card so that it can record up to 3 channels at the same time. They always like to put shows on at near the same time and you have to allow overlap when using timers. And this setup monitors the epg for shows and sets up the timers as the come up in the guide, then put the recordings into folder by show for series shows. We can then watch them when we want. Sort of a custom built tvio. VDR does have plugins for dish rotors, sat switches but no support for antenna rotors and there no electronicly controlled switches for OTA which would do any good anyway as the dual tuner only has 1 input. So the antenna needs to be able to supply all the stations down the same cable. I was thinking about using high gain antennas at first. But the common thought was wouldn't work well. Needing 3 directions makes it harder because a bi-directional can still only aim at one at a cost of gain to the other. And there is the phase differance of 2-3 antennas.

2009-09-05, 11:37 AM	#401
holl_ands Veteran Join Date: Nov 2008 Location: San Diego, CA Posts: 1,600	Vorg: I've had the time to track down and look at your TVFool results. I originally thought you had three tower groups ALL WITHIN a 120-deg span....not quite.... I now see that most of your towers are within a 139-deg arc (260 to 39-deg) plus The CW (your strongest) at 171-deg. Because most antennas have a NULL at 90-deg from the beam, they're always operating at reduced Gain on the sidelobes. I wouldn't worry too much about The CW....it's strong enough to come in on the BACK of most any antenna. So for BEST performance OUTSIDE, I'm still recommending using two high gain Hi-VHF/UHF antennas with a combiner....such as NAROD SBGHs or M4s. You have a mix of UHF (39-deg, 260 & 275-deg), Hi-VHF (39-deg & 275-deg)....and Ch4 K04QP-D (please say you can survive if it isn't picked up by a Hi-VHF antenna....) ============================================= The Hoverman Type 1 Omni is still a candidate, although your beamwidth spread is a little bit wider (139 vice 120-deg). The NULL is along the same direction as the Balun wire connections. It would be oriented so that it is directed about 15-deg AWAY from 171-deg (The CW), choosing one side or the other, depending on whether you want to favor 39-deg or 260/275-deg. BTW: The Type 1 Omni has 3.3-3.9 dBi Raw Gain on Ch7-13, but with a very high SWR (as is common when using UHF antennas for Hi-VHF). I added Hi-VHF plots: http://imageevent.com/holl_ands/grayhoverman So you have a good chance of also picking up Ch 9, 13 and maybe Ch7. And if you DO have Hi-VHF reception problems, you could add a Hi-VHF Loop. ================================================= But I would first try the UHF Square Loop----OUTSIDE. You have lots of strong signals and are likely suffering from "Indoor Antenna Syndrome", which will probably clear up by moving it OUTSIDE, where it can get plenty of sunshine.....but it won't have much Gain on Hi-VHF channels....or Ch4. There may also be some "better" alternatives to the Type 1 Omni Hoverman.... PS: But even with a big high gain antenna, those stations with significantly negative "NM" just aren't in your future....

2009-09-05, 11:47 AM	#402
wildwillie Join Date: Jan 2009 Posts: 280	holl_ands , http://www.jedsoft.org/fun/antennas/omni/omni.html I was tring to make that design work , for x396

2009-09-05, 11:54 AM	#403
holl_ands Veteran Join Date: Nov 2008 Location: San Diego, CA Posts: 1,600	I was thinking I saw it in an ARRL publication....maybe one of the Antenna Compendiums.....

2009-09-06, 09:57 AM	#405
holl_ands Veteran Join Date: Nov 2008 Location: San Diego, CA Posts: 1,600	I was looking at post #104 in the Fractal thread: http://www.digitalhome.ca/forum/showthread.php?p=957893 If you used your street address, you might find more believeable results using LAT/LOG, such as from GoogleEarth.....or perhaps The CW's ERP is less than that assumed in TVFool.....