The Official AVS Antenna and Related Hardware Topic! - Page 542 - AVS Forum
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post #16231 of 16246 Old 07-03-2014, 11:55 AM
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Quote:
Originally Posted by deltaguy View Post
If 12.1 continues without problems, you're good to go. I wouldn't assume that interference can be ruled out by the microwave not causing a problem. All electrical devices are not created equal.
Well now I am back to square one again.

Tried a new antenna& same issue again.swing the mounting arm gets 12.1 to work but pushing it back to put the TV away in the cabinet - stops 12.1 from working.

Something is interfering with it.

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post #16232 of 16246 Old 07-03-2014, 03:31 PM
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What new antenna did you try?

The manual says:

"Note: The ANT1400 may work well sitting on your TV or other components. However, because electronic components (like your TV) can sometimes interfere with the antenna's reception, you might notice an effect on the antenna's
performance. Likewise, placing the antenna on a metal surface may interfere with reception. If the antenna isn't performing as well as expected, try moving it away from the component or placing it on another surface. Then, re-scan for channels on your TV or converter box."
http://manuals.solidsignal.com/ANT1400_Manual.pdf

I'm very skeptical about claims for an antenna being multi-directional. Notice that CH12 is almost at a right angle from your other channels.

If your tests tell you that the antenna needs to be further away from the TV, then you must believe your test results and go to plan B.

Other posters have told you that CH12 is on VHF, which is more prone to electrical interference, and your all-channel antenna may not perform as well on VHF as it does on UHF. I agree with them.

If you can not measure it, you can not improve it.
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Last edited by rabbit73; 07-16-2014 at 07:35 PM.
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post #16233 of 16246 Old 07-03-2014, 03:42 PM
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Quote:
Originally Posted by :
Something is interfering with it.
Well, duh! You put it right behind the TV and it fails. You move the TV away from the antenna and it works.

This shouldn't be hard to figure out....
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post #16234 of 16246 Old 07-08-2014, 08:16 AM
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Charles Rhodes article on Inter-Band RFI:

http://www.tvtechnology.com/digital-...s-worry/271017

Some of you folks will certainly find this of interest.

Tech support for Antennas Direct
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post #16235 of 16246 Old 07-09-2014, 01:38 PM
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Quote:
Originally Posted by ADTech View Post
Charles Rhodes article on Inter-Band RFI:

http://www.tvtechnology.com/digital-...s-worry/271017

Some of you folks will certainly find this of interest.
I did. I have a comment. RF frequencies intersect, whether there are filters on a receiver or not. Filters can prevent some reception problems, but cannot stop RF from intersecting.
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post #16236 of 16246 Old 07-18-2014, 12:21 PM
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Vertically Stacked Hourglass Antennas - No Reflector:

Uploaded 4nec2 Results for two Vertically Stacked Hourglass Antennas (No Reflectors) with Stacking Distance Optimized for best Raw Gain, using nikiml's Python Optimization Scripts:
http://imageevent.com/holl_ands/stac...lassloopnorefl

An UHF Hourglass-Loop has a VERY WIDE Beamwidth of 80-deg at 470 MHz, decreasing to 70-deg at 698 MHz. Vertically Stacked, remains 80-deg at 470 MHz, decreasing to 60-deg at 698 MHz (to within 10-deg resolution).

Two versions were presented, the first presumes the use of an RF Combiner attached
to Antenna Feedpoints using Baluns & Equal Length Cables. The second avoids 0.5-1.5+ dB Loss in RF Combiner by using an Optimized Vertical Interconnection Harness.

a) RF Combiner: Vertical Stacking (Center-Center), VD = 18-in provides Max Raw Gain per Optimizer.

UHF Raw Gain = 7.6 to 9.6 dBi and SWR (300-ohms) under 1.9.

=====================================
b) Holl_ands Vertical Harness (HVH): Vertical Stacking (Center-Center), VD = 24.75-in provides Max Raw Gain per Optimizer. See 4nec2 File for all Dimensions, including Re-Optimized Hourglass-Loop sizes.

UHF Raw Gain FORWARD = 7.8 to 9.7 dBi, F/B & F/R Ratio has small (1.3 dB) increase at high frequencies (just -0.1 dB at low frequencies), and SWR (300-ohms) under 2.1.

Hence HVH provides about the SAME performance as RF Combiner Mod, but WITHOUT the RF Combiner Loss.

Dimensions of HVH wires were determined using nikiml's Python Optimization Scripts:
VS = 12.25-in = Vertical Stacking Distance (Center-To-Center).
VS/2 = 6.125-in, Length of Harness wires from Feedpoint to Center of each Hourglass-Loop.
Diagonal = 3.25-in, Length from Harness Wires to each Hourglass-Loop Feedpoint.
Hw = 0.80-in (may round to 0.75-in),
Xh = -3.25-in = Harness X-Axis Separation from Hourglass-Loops.
TOTAL HARNESS WIRE LENGTH (2 required) = 19.75-in = 2x6.125+2x3.25+2x0.5 (for eyelets)



RAW GAIN FORWARD (F/B & F/R NOT CALCULATED):


RAW GAIN TO REVERSE:




Last edited by holl_ands; 07-20-2014 at 10:01 AM.
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post #16237 of 16246 Old 07-18-2014, 12:31 PM
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Vertically Stacked Hourglass Antennas + 15 Reflector Rods:

Uploaded 4nec2 Results for two Vertically Stacked Hourglass Antennas, with 15 Reflector Rods:where nikiml's Python Optimization Scripts were used to Optimize dimensions of the HVH (Hollands Vertical Harness) and Separation between Hourglass-Loops:
http://imageevent.com/holl_ands/stac...rglassloop15rr

UHF Raw Gain = 12.6 to 13.7 dBi, F/B & F/R Ratio Min = 18.3 dB and SWR (300-ohms) under 2.8.
Beamwidth = 60-degrees was CONSTANT vs Frequency.

Dimensions of HVH wires were determined using nikiml's Python Optimization Scripts:
VS = VS=17.5-in = Vertical Stacking Distance (Center-To-Center).
VS/2 = 8.75-in, Length of Harness wires from Feedpoint to Center of each Hourglass-Loop.
Diagonal = 1.0-in, Length from Harness Wires to each Hourglass-Loop Feedpoint.
Hw = 1.125-in (may round to 1.5-in),
Xh = -0.5-in = Harness X-Axis Separation from Hourglass-Loops.
TOTAL HARNESS WIRE LENGTH (2 required) = 20.5-in = 2x8.75+2x1.0+2x0.5 (for eyelets)






Last edited by holl_ands; 07-20-2014 at 10:03 AM.
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post #16238 of 16246 Old 07-18-2014, 12:37 PM
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Horiz-Stack UHF Hourglass-Loop - NO Refl

Horizontally Stacked UHF Hourglass-Loops (NO Reflectors) analyzed using 4nec2.
All dimensions were determined using nikiml's Python Optimization Scripts:
http://imageevent.com/holl_ands/stac...lassloopnorefl

An UHF Hourglass-Loop has a VERY WIDE Beamwidth of 80-deg at 470 MHz, decreasing to 70-deg at 698 MHz. Horizontally Stacked, it drops to 40-deg at 470 MHz, and 30-deg at 698 MHz (to within 10-deg resolution).

Two versions are presented here, the first presumes the use of an RF Combiner attached
to Antenna Feedpoints using Baluns & Equal Length Cables. The second avoids 0.5-1.5+ dB Loss
in RF Combiner by using an Optimized Horizontal Interconnection Harness.

a) RF Combiner: Horizontal Stacking (Center-Center), HD = 16-in provides Max Raw Gain per Optimizer.
UHF Raw Gain = 7.8 to 9.8 to 9.5 dBi and (300-ohms) under 1.9.

=====================================
b) Holl_ands Horizontal Harness (HHH): Interconnection using HHH rather than RF Combiner, otherwise ALL Dimensions are the SAME as the above Model.

Dimensions of HHH wires were determined using nikiml's Python Optimization Scripts:
HD = 16.0-in = Horizontal Stacking Distance (Center-To-Center).
HD/2 = 8.0-in, Length of Harness wires from Feedpoint to Center of each Hourglass-Loop.
Diagonal = 4.0-in, Length from Harness Wires to each Hourglass-Loop Feedpoint.
Hw = 1.43-in (may round to 1.5-in),
Xh = -3.75-in = X-Axis Separation between Harness Wires and Hourglass-Loops.
TOTAL HARNESS WIRE LENGTH (2 required) = 25-in = 2x8.0+2x4.0+2x0.5 (for eyelet)

UHF Raw Gain = 8.6 to 10.1 dBi, F/B and F/R Ratio = 3.5 to 1.8 dB and (300-ohms) under 1.9.

Note that HHH acts somewhat as a REFLECTOR, increasing Raw Gain in the Forward direction, providing significantly MORE Gain than RF Combiner Model above....and NO LOSS due to Combiner.







Last edited by holl_ands; 07-20-2014 at 09:38 AM.
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post #16239 of 16246 Old 07-18-2014, 12:47 PM
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Horiz-Stack UHF Hourglass-Loop + 15 Reflector Rods

Horizontally Stacked UHF Hourglass-Loops + 15 Reflector Rods analyzed using 4nec2, where nikiml's Python Optimization Scripts were used to Optimize dimensions of the HHH (Hollands Horizontal Harness) and Separation between Hourglass-Loops. Alternatively, Sidelobes would be minimized with minimum Separation:
http://imageevent.com/holl_ands/stac...rglasslooprefl

UHF Raw Gain = 12.6 +/- 0.1 dBi is VERY FLAT, F/B & F/R Ratio Min = 16.5 dB
and SWR (300-ohms) under 2.7.

Dimensions of HHH wires were determined using nikiml's Python Optimization Scripts:
HD/2 = 14.5-in, Length of Harness wires from Feedpoint to Center of each Hourglass-Loop.
Diagonal = 4.5-in, Length from Harness Wires to each Hourglass-Loop Feedpoint.
Hw = 1.875-in, Separation between Harness Wires.
Xh = -4.25 = X-Axis Separation between Harness Wires and Hourglass-Loops.
TOTAL HARNESS WIRE LENGTH (2 required) = 39-in = 2x14.5+2x4.5+2x0.5 (for eyelet)








Last edited by holl_ands; 07-20-2014 at 09:39 AM.
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post #16240 of 16246 Old Yesterday, 06:19 AM
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UHF Quad-Trapezoid-Loop - NO Reflector:

UHF Quad-Trapezoid-Loop (NO Reflector) Antenna analyzed using 4nec2, formed by adding outer parts of Chireix 2-Square to an Hourglass-Loop. All dimensions determined using nikiml's Optimization Scripts:
http://imageevent.com/holl_ands/loop...dtrapezoidloop

UHF Raw Gain = 6.7 to 8.4 to 7.8 dBi and SWR (300-ohms) under 1.8.
Note Very Wide 70-60 degree Beamwidth.







Beamwidth = 60-degrees at 698 MHz, you won't see THAT in a 4-Bay Bowtie:
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post #16241 of 16246 Old Yesterday, 06:26 AM
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UHF Quad-Trapezoid-Loop - 15 Reflector Rods:

UHF Quad-Trapezoid-Loop with 15 Reflector Rods analyzed using 4nec2, formed by adding outer parts of Chireix 2-Square to an Hourglass-Loop. All dimensions determined using nikiml's Optimization Scripts:
http://imageevent.com/holl_ands/loop...dtrapezoidloop

UHF Raw Gain = 10.1 to 11.8 dBi, F/B & F/R Ratio Min =19.2 dB and SWR (300-ohms) under 2.7.
Note VERY WIDE BANDWIDTH, 60-degrees ALL across the UHF Band and the VERY DEEP
49+ dB Notch directly to the Rear.


Clearly it wouldn't hurt to add another pair (or two or three) of Reflector Rods to push the F/R Ratio even higher....which I plan to do in the near future...but for now I'm working on some Apples-To-Apples Comparisons for Wide Beamwidth alternatives....







Beamwidth=60-degrees at 698 MHz, you won't see THAT in a 4-Bay Bowtie:

Last edited by holl_ands; Yesterday at 06:33 AM.
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post #16242 of 16246 Old Yesterday, 06:44 AM
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UHF Quad-Trapezoid-Loop + 2xBars - No Reflector:

UHF Quad-Trapezoid-Loop + 2 Bar Elements (No Reflector) analyzed using 4nec2. Formed by adding outer parts of Chireix 2-Square Antenna to an Hourglass-Loop. All dimensions determined using nikiml's Optimization Scripts:

UHF Raw Gain = 6.6 to 9.4 dBi, SWR (300-ohms) under 1.8 and Beamwidth = 80 to 50-degrees.








BEAMWIDTH = 50-DEGREES AT 698 MHZ:


Last edited by holl_ands; Yesterday at 06:52 AM.
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post #16243 of 16246 Old Yesterday, 06:51 AM
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UHF Quad-Trapezoid-Loop + 2xBars - 15 Reflector Rods:

UHF Quad-Trapezoid-Loop + 2 Bar Elements with 15 Reflector Rods analyzed using 4nec2. Formed by adding outer parts of Chireix 2-Square Antenna to an Hourglass-Loop. All dimensions determined using nikiml's Optimization Scripts:

UHF Raw Gain = 11.4 to 12.6 to 11.1 dBi, F/B & F/R Ratio Min = 18.1 dB and SWR (300-ohms) under 2.5.
Note 60-50 degree Beamwidth and EXTREMELY DEEP 64+ dB Notch directly to Rear.

Again, it wouldn't hurt to add another pair (or two or three) of Reflector Rods to push the F/R Ratio even higher....which I plan to do in the near future...but for now I'm working on some Apples-To-Apples Comparisons for Wide Beamwidth alternatives....



NOTE GOOD GAIN ON LOWER CHANNELS, BUT AT EXPENSE OF ROLL-OFF ON HIGHEST CHANNELS:




BEAMWIDTH = 50-DEGREES AT 698 MHZ:

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post #16244 of 16246 Old Yesterday, 01:34 PM
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I'm sure it's probably in these 542 pages of information somewhere, but it would take me days to find it. I was wondering if anyone had done a side by side comparison of the 91XG and the CM4228. I know that the 91XG has a much narrower beam than the 4228, but I'm more interested on gain. I have a 4228 and there are a few stations that are just a dB or two below the cliff edge that would be nice to receive. Would the 91XG possibly make this happen?

Thanks
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post #16245 of 16246 Old Yesterday, 03:40 PM
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It might make it happen. The gain curves of those two antennas are not flat, so a lot depends upon the frequency of the needed channels. What RF channels do you need?
http://www.hdtvprimer.com/antennas/comparing.html

I can't find your tvfool report.

It is possible to make a halfwave balun for the 91XG that replaces its normal balun. The halfwave balun might have less loss. Since it is a narrowband device, it needs to be cut for the frequency of the weakest channel.

Another approach would be to modify your 4228. It is possible to combine the two 4-bay antennas in a different manner than the original. You could use two 4:1 ferrite baluns with a splitter as a combiner, two 4:1 halfwave baluns with a low-loss combiner, or a special holl_ands harness:
http://www.digitalhome.ca/forum/show...&postcount=248

If you can not measure it, you can not improve it.
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Last edited by rabbit73; Yesterday at 07:05 PM.
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post #16246 of 16246 Old Today, 12:09 AM
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Quote:
Originally Posted by rabbit73 View Post
It might make it happen. The gain curves of those two antennas are not flat, so a lot depends upon the frequency of the needed channels. What RF channels do you need?
http://www.hdtvprimer.com/antennas/comparing.html

I can't find your tvfool report.
Thanks for the response, Rabbit. I wrote a response here earlier, but the server got hung up and it never got saved, so I'll try again.

Thanks for the link to the antenna comparison graph. It looks like the 91XG does better above channel 36, while the 4228 appears to be better below 36. I see that there's no big difference in gain overall.

Here's my TVFool report:

http://www.tvfool.com/?option=com_wr...e1c67a311959ac

The channels I don't receive are mixed in with those I do receive. I receive every station on the TVFool list down through KVIE 9, but also receive KMAX 21, KQCA 46, and KEMO 32 all the time with good signals. KOVR 25, KCRA 35 and KAXT 42 are sometimes there, but aren't reliable. Those three plus KTFK 26 and KSPX 48 are the ones I'd like to pull in that are mostly just below the cliff edge, usually at around 13 to 15 dB.

Three are below the channel 36 cross-over for the two antennas, two are above 36, so I don't think changing from the 4228 to the 91XG will be worth the time and money involved.

I'd love to use a pre-amp, but as you can see from the TVFool list, I'm really close to Sutro Tower and the 11 stations transmitting from up there. The tower is less than a mile from here. While the main lobes go over us, those signals are still really strong and I haven't found a preamp that's not overloaded by them.

Looks like what I've got is the best I can do.

Thanks again for your input.

Larry
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