The Official AVS Antenna and Related Hardware Topic! - Page 542 - AVS Forum
Forum Jump: 
Reply
 
Thread Tools
post #16231 of 16253 Old 07-03-2014, 11:55 AM
AVS Special Member
 
tripleM's Avatar
 
Join Date: Jan 2007
Posts: 2,052
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked: 12
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.

Panasonic TC-P60ST60 + Sony STR-DG810 + LG BH200 + JBL L830's x2 + JBL LC1 + JBL Loft40 x 2 + Polk PSW10 + Harmony One
tripleM is offline  
Sponsored Links
Advertisement
 
post #16232 of 16253 Old 07-03-2014, 03:31 PM
Advanced Member
 
rabbit73's Avatar
 
Join Date: Apr 2008
Location: S.E. VA
Posts: 876
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked: 14
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.
Lord Kelvin, 1883
www.megalithia.com/elect/aerialsite/dttpoorman.html

Last edited by rabbit73; 07-16-2014 at 07:35 PM.
rabbit73 is offline  
post #16233 of 16253 Old 07-03-2014, 03:42 PM
AVS Special Member
 
ProjectSHO89's Avatar
 
Join Date: Feb 2009
Posts: 2,533
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 22 Post(s)
Liked: 60
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....
ProjectSHO89 is offline  
post #16234 of 16253 Old 07-08-2014, 08:16 AM
Senior Member
 
ADTech's Avatar
 
Join Date: Jun 2010
Location: St Louis
Posts: 418
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 7 Post(s)
Liked: 27
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
ADTech is offline  
post #16235 of 16253 Old 07-09-2014, 01:38 PM
Senior Member
 
difuse's Avatar
 
Join Date: Oct 2011
Posts: 463
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked: 13
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.
difuse is online now  
post #16236 of 16253 Old 07-18-2014, 12:21 PM
AVS Special Member
 
holl_ands's Avatar
 
Join Date: Jun 2004
Location: San Diego, CA
Posts: 3,591
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 18 Post(s)
Liked: 52
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.
holl_ands is offline  
post #16237 of 16253 Old 07-18-2014, 12:31 PM
AVS Special Member
 
holl_ands's Avatar
 
Join Date: Jun 2004
Location: San Diego, CA
Posts: 3,591
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 18 Post(s)
Liked: 52
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.
holl_ands is offline  
post #16238 of 16253 Old 07-18-2014, 12:37 PM
AVS Special Member
 
holl_ands's Avatar
 
Join Date: Jun 2004
Location: San Diego, CA
Posts: 3,591
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 18 Post(s)
Liked: 52
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.
holl_ands is offline  
post #16239 of 16253 Old 07-18-2014, 12:47 PM
AVS Special Member
 
holl_ands's Avatar
 
Join Date: Jun 2004
Location: San Diego, CA
Posts: 3,591
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 18 Post(s)
Liked: 52
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.
holl_ands is offline  
post #16240 of 16253 Old 07-21-2014, 06:19 AM
AVS Special Member
 
holl_ands's Avatar
 
Join Date: Jun 2004
Location: San Diego, CA
Posts: 3,591
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 18 Post(s)
Liked: 52
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:
holl_ands is offline  
post #16241 of 16253 Old 07-21-2014, 06:26 AM
AVS Special Member
 
holl_ands's Avatar
 
Join Date: Jun 2004
Location: San Diego, CA
Posts: 3,591
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 18 Post(s)
Liked: 52
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; 07-21-2014 at 06:33 AM.
holl_ands is offline  
post #16242 of 16253 Old 07-21-2014, 06:44 AM
AVS Special Member
 
holl_ands's Avatar
 
Join Date: Jun 2004
Location: San Diego, CA
Posts: 3,591
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 18 Post(s)
Liked: 52
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; 07-21-2014 at 06:52 AM.
holl_ands is offline  
post #16243 of 16253 Old 07-21-2014, 06:51 AM
AVS Special Member
 
holl_ands's Avatar
 
Join Date: Jun 2004
Location: San Diego, CA
Posts: 3,591
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 18 Post(s)
Liked: 52
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:

holl_ands is offline  
post #16244 of 16253 Old 07-21-2014, 01:34 PM
AVS Special Member
 
Larry Kenney's Avatar
 
Join Date: Nov 2001
Location: San Francisco, CA
Posts: 2,571
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 19 Post(s)
Liked: 27
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
Larry
SF

My complete SF Bay Area DTV Station Lists: http://www.choisser.com/sfonair.html
Lots of Broadcasting links and information: http://www.choisser.com/broadcast.html

Check out photos and info on my antennas: http://www. larrykenney.com/tvantennas.html

Larry Kenney is offline  
post #16245 of 16253 Old 07-21-2014, 03:40 PM
Advanced Member
 
rabbit73's Avatar
 
Join Date: Apr 2008
Location: S.E. VA
Posts: 876
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked: 14
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 coaxial halfwave balun for the 91XG that replaces its normal balun. The halfwave balun is a narrowband device in comparison to a 4:1 ferrite balun which is designed to cover the VHF and UHF TV bands.
But, if you cut it for the center of the UHF band, it will outperform the ferrite balun for the whole band. However, if you are interested in only the low or high end of the UHF band, you should cut it for that end to reduce the balun loss to a minimum.

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.
Lord Kelvin, 1883
www.megalithia.com/elect/aerialsite/dttpoorman.html

Last edited by rabbit73; 07-23-2014 at 09:23 AM.
rabbit73 is offline  
post #16246 of 16253 Old 07-22-2014, 12:09 AM
AVS Special Member
 
Larry Kenney's Avatar
 
Join Date: Nov 2001
Location: San Francisco, CA
Posts: 2,571
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 19 Post(s)
Liked: 27
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
SF

My complete SF Bay Area DTV Station Lists: http://www.choisser.com/sfonair.html
Lots of Broadcasting links and information: http://www.choisser.com/broadcast.html

Check out photos and info on my antennas: http://www. larrykenney.com/tvantennas.html

Larry Kenney is offline  
post #16247 of 16253 Old 07-22-2014, 07:22 AM
AVS Special Member
 
Calaveras's Avatar
 
Join Date: Jan 2007
Location: Mountain Ranch
Posts: 2,808
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 48 Post(s)
Liked: 73
Quote:
Originally Posted by rabbit73 View Post
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. ]
The 300 ohm coaxial balun is a broadband device. See a modeled plot for an FM version here:

http://www.ham-radio.com/k6sti/balun.htm

Scroll down to 300 ohm Balun.


I'm using a UHF version on my 91XGs. I built two of them, connected them back to back, measured the insertion loss and divide by 2. The highest loss was only around 0.2 dB, much better than either the ferrite balun or the PC balun, both of which measured around 1 dB max loss.
Attached Images
File Type: jpg Balun-1.jpg (44.0 KB, 11 views)
File Type: jpg Balun-2.jpg (110.0 KB, 9 views)
Calaveras is offline  
post #16248 of 16253 Old 07-22-2014, 10:38 AM
Advanced Member
 
rabbit73's Avatar
 
Join Date: Apr 2008
Location: S.E. VA
Posts: 876
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked: 14
Larry:

Thanks for the tvfool report. You certainly are in overload territory.

The only way I can think of for you to be able to receive one of those weak stations would be to have an antenna dedicated to that channel with a TinLee single channel bandpass filter for that channel and a preamp. Your best chance would be with KOVR; KCRA and KAXT are weaker and have co-channel and adjacent channel interference.

The reason I suggested a modification to your CM4228 is because its combining harness is known to have high losses. The antenna doesn't deliver anything near the hoped for 3 dB gain over one 4-bay antenna.
http://www.hdtvprimer.com/antennas/cm4228.html

The 4228 is a collinear array. The ARRL Antenna Book has this to say about them:

"Large broadside collinear antennas can be checked for excessive phasing-line losses by comparing the gain computed from the radiation patterns with the direct-measured gain. It seems paradoxical, but it is indeed possible to build a large array with a very narrow beamwidth indicating high gain, but actually having very low gain because of losses in the feed distribution system."

Last edited by rabbit73; 07-22-2014 at 03:57 PM.
rabbit73 is offline  
post #16249 of 16253 Old 07-22-2014, 11:27 AM
Advanced Member
 
rabbit73's Avatar
 
Join Date: Apr 2008
Location: S.E. VA
Posts: 876
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked: 14
Chuck:

Thanks for the photos of your low-loss baluns. I see that, as a precaution, you have added ferrite beads to your coax balun. Do you have any photos of your UHF combiner?

I can't get that link to Brian to work:
http://www.ham-radio.com/k6sti/balun.htm

I think that the document you see on your screen is not from that link, but from a copy stored in your computer. Check your URL address window when it comes up.

I read that he has retired from ham radio and computer modeling.
http://hamwaves.com/antennas/modelling.html

Brian's website is down. I think he got fed up with the aggravations caused by other people when he was trying to do what he loved best.
http://ham-radio.com/k6sti/
http://www.ham-radio.com/k6sti

All that is left is a Google cache of his home page:
http://webcache.googleusercontent.co...&ct=clnk&gl=us

and text only versions of Baluns for 88-108 MHz:
http://webcache.googleusercontent.co...&ct=clnk&gl=us
http://webcache.googleusercontent.co...&gl=us&strip=1

DHC has a thread with some posts about coax baluns:
http://www.digitalhome.ca/forum/showthread.php?t=100512

You have to login and refresh to make the images show in a post on that forum.

Brian did this:



If you are going for the last 0.5 dB, the loss curve doesn't look very flat to me. It shows a loss of 0.5 dB at each end of the UHF band, when the half-wave balun is cut for the center of the band. The balun just covers the band while keeping the loss from being greater than 0.5 dB. I consider that to be narrowband when compared to the ferrite VHF/UHF balun that it replaces.

I edited my description of a half-wave coaxial balun in post 16245 to Larry. I hope that you will find it more accurate.

Last edited by rabbit73; Yesterday at 11:32 AM. Reason: Added diagram and deleted links that Chuck couldn't use.
rabbit73 is offline  
post #16250 of 16253 Old 07-22-2014, 04:21 PM
AVS Special Member
 
holl_ands's Avatar
 
Join Date: Jun 2004
Location: San Diego, CA
Posts: 3,591
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 18 Post(s)
Liked: 52
Hi-VHF Goalkeeper Quad-Trapezoid+Spurs - Quasi-Omni:

I uploaded 4nec2 analysis for the Hi-VHF Goalkeeper, a Quasi-Omni [accidental] variation of the Quad-Trapezoid+Spurs, assuming QICT (Quarter-Inch Copper Tubing). By accident, because I noticed one with favorable properties for a quite different application when looking at the Optimizer's early best*.***.nec Files for the above NO Reflector Quad-Trap.

Hi-VHF Raw Gain = 2.1 to 2.9 dBi (Forward & Rear) and SWR (300-ohms) under 1.8 (Excellent). Beamwidth = 100-110 degrees. [For QICT, could substitute AWG10 with higher SWR.]

Provides Bi-Directional Pattern firmly aligned along the X-Axis with wide Beamwidth and NULLs to the sides. Although Horizontally Polarized, it also provides both Right-Hand and Left-Hand Circular Polarization, but with only 1 dB LHCP suppression.

I also added an FM version to the Omni/Quasi-Omni webpage for comparison purposes:
http://imageevent.com/holl_ands/omni...trapezoidspurs

Although Folded Vertical Dipole provides TRUE Omni coverage for Vertically Polarized signals, ALL of the "Quasi-Omni's" designed for Horizontal Polarization are either Bi-Directional....or have very irregular Patterns. The Goalkeeper is unusual, providing a wide Beamwidth, a reasonable amount of POSITIVE Gain on ALL frequencies (at least Forward and to Rear) and Excellent SWR....a combination that is very rare.

PS: When an Antenna's Beamwidth is less than 90-degrees, I would simply call it a Bi-Directional Antenna...like most any other Antenna without a Reflector. And when a Bi-Directional Antenna's Beamwidth is 90-degrees or more, I call it a "Quasi-Omni" Antenna....like commercial FM Turnstiles....that are far from a TRUE OMNI with 360 degrees of useful azimuthal coverage.

BTW: With a tip of the hat to some would-be FIFA players, I came up with the full name: "Mindless Goalkeeper"....after rejecting the tasteless "Headless Goalkeeper".....or "Jumping Jacks"....or (my wife's idea) "Up Against The Wall and Spread 'Em".





AZIMUTHAL PATTERN (Note Negligible response to Vertical Polarization):


CIRCULAR POLARIZATION PATTERN:

Last edited by holl_ands; 07-22-2014 at 04:46 PM.
holl_ands is offline  
post #16251 of 16253 Old 07-22-2014, 05:47 PM
AVS Special Member
 
Calaveras's Avatar
 
Join Date: Jan 2007
Location: Mountain Ranch
Posts: 2,808
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 48 Post(s)
Liked: 73
Quote:
Originally Posted by rabbit73 View Post
Chuck:

Thanks for the photos of your low-loss baluns.

I can't get that link to Brian to work:

http://www.ham-radio.com/k6sti/balun.htm

I read that he has retired from ham radio and computer modeling.
http://hamwaves.com/antennas/modelling.html

I did find these two posts by Brian:
http://www.digitalhome.ca/forum/show...2&postcount=30
http://www.digitalhome.ca/forum/show...2&postcount=59

If you are going for the last 0.5 dB, those loss curves don't look very flat to me.

You have to login and refresh to make the images show in a post on that forum.

I edited my description of a halfwave coaxial balun in post #16245 to Larry. I hope that you will find it more accurate.
I'm not a member there so I can't see the images. I'm not having any trouble with the link I posted. I'm not saying that the coax baluns are flat. I'm saying they are much lower loss than either the ferrite or PCB balun.
Calaveras is offline  
post #16252 of 16253 Old 07-22-2014, 06:28 PM
AVS Special Member
 
Calaveras's Avatar
 
Join Date: Jan 2007
Location: Mountain Ranch
Posts: 2,808
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 48 Post(s)
Liked: 73
Quote:
Originally Posted by rabbit73 View Post
Larry:

Thanks for the tvfool report. You certainly are in overload territory.
You would think that was the case and I thought so too until I went to Larry's place and measured his signals on my spectrum analyzer. His signals are in the same strength range as mine and I'm 54 miles and 2 edges from the transmitters. The key was the fact that he is 18.5 degrees below the main lobe so the ERP is reduced by a huge factor.

Attached is a spaghetti graph where I took the vertical elevation patterns from the applications filed by the stations with the FCC to get their construction permits for their post transition stations. The graphs didn't go down to 18.5 degrees so I extrapolated the graph. At that angle the field strength averages only 1%. See attachment. That means he's only seeing tens to a few hundred watts ERP from Sutro Tower. Of course that is plenty of power at 3/4 mile LOS! It's actually a good deal because it prevents overload. The bad part is that when you're way off the main lobe, the ERP can vary greatly with frequency. The second image is KRON, Larry's strongest UHF station. The 3rd image is KCSM, KTVU and KBCW on RF 43 - 45. Those ugly signals are caused by being so far below the main lobe.

For comparison I attached an image of KOVR received here. It's in the same range as Larry's signals. I actually do have an overload problem and it is KUVS shown in the final image. That's 60KW ERP 14 miles LOS. I have to use a 25 dB notch filter in front of the TV prevent overload. It's about 25 dB stronger than anything Larry is seeing.

The problem with living in San Francisco that I don't have is the tremendous number of strong out of band transmitters. That's likely the real overload problem, not the TV transmitters.
Attached Images
File Type: jpg Sutro Vertical Patterns.jpg (171.2 KB, 10 views)
File Type: gif KRON.gif (23.1 KB, 9 views)
File Type: gif KCSM KTVU KBCW.gif (22.2 KB, 7 views)
File Type: gif KOVR_annotated.gif (23.4 KB, 6 views)
File Type: gif KUVS.gif (22.8 KB, 7 views)
Calaveras is offline  
post #16253 of 16253 Old 07-23-2014, 01:01 AM
AVS Special Member
 
Larry Kenney's Avatar
 
Join Date: Nov 2001
Location: San Francisco, CA
Posts: 2,571
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 19 Post(s)
Liked: 27
There is definitely a lot of extraneous RF floating around here! On my HD HomeRun receivers, there's always a signal of 22% or higher on the channels with no 8vsb signals. Channels 59, 60 and 61 have signals of 95 to 100% no matter what antenna I select and there are no TV signals on those channels.

Many people have been surprised that I'm able to receive as many stations as I do, and some of them are adjacent to channels with signals from Sutro Tower. While I'm sure adjacent channel signals are affecting my reception, I'm getting 20+ dB SNR signals on stations 62-65 miles away that are adjacent to Sutro stations. Examples:
KEMO 32 Mt. St. Helena 65 miles - KMTP 33 Sutro
KFSF 34 Sutro - KCRA 35 Walnut Grove 62 miles
KBCW 45 Sutro - KQCA 46 Walnut Grove 62 miles - KTLN 47 Novato 30 miles

I do have problems with KCRA for a different reason. KGO's translator, 35 miles SW of here, is also on channel 35. When KGO's signal is down, I get KCRA. When KGO's signal is up, KCRA drops below the cliff edge. Prior to the translator coming on the air I received KCRA in the 20 to 22 dB range.

Looking at the various possibilities for increasing my distant signals you guys have mentioned, I don't think the little increased gain will be worth the time and money I'll have to spend, so I'm just going to leave things as they are. Thanks for your input. It's been an interesting discussion!

Those interested in seeing my antennas can check out the link below.

Larry
San Francisco

My complete SF Bay Area DTV Station Lists: http://www.choisser.com/sfonair.html
Lots of Broadcasting links and information: http://www.choisser.com/broadcast.html

Check out photos and info on my antennas: http://www. larrykenney.com/tvantennas.html

Larry Kenney is offline  
Reply HDTV Technical

Tags
Channel Master Cm 4228 8 Bay Hdtv Uhf Antenna Cm4228hd
Gear in this thread

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off