The Official AVS Antenna and Related Hardware Topic! - Page 600 - AVS Forum | Home Theater Discussions And Reviews
Forum Jump: 
 420Likes
Reply
 
Thread Tools
post #17971 of 18330 Old 01-15-2020, 08:22 AM
AVS Forum Special Member
 
rabbit73's Avatar
 
Join Date: Apr 2008
Location: S.E. VA
Posts: 3,498
Mentioned: 23 Post(s)
Tagged: 0 Thread(s)
Quoted: 1009 Post(s)
Liked: 450
Quote:
Originally Posted by labjr View Post
I saw a comment by Antennas Direct Tech support, which I can't find now, that said the Max-V was the same antenna as the 2Max.
Antennas Direct posted this reply for their video:
Quote:

The MAX-V is the same antenna as the 2MAX. There are limited installation components, so you only buy what you need for your antenna setup. Meaning, the antenna comes with a wall bracket and adjustable mounting hardware for a mast - you would need to purchase a mast, coaxial cable, and if you would like to use the antenna indoors, we have a base stand that is sold separately as well.

If you can not measure it, you can not improve it.
Lord Kelvin, 1883
www.megalithia.com/elect/aerialsite/dttpoorman.html
rabbit73 is online now  
Sponsored Links
Advertisement
 
post #17972 of 18330 Old 01-15-2020, 12:00 PM
AVS Forum Special Member
 
rabbit73's Avatar
 
Join Date: Apr 2008
Location: S.E. VA
Posts: 3,498
Mentioned: 23 Post(s)
Tagged: 0 Thread(s)
Quoted: 1009 Post(s)
Liked: 450
Quote:
Originally Posted by MSZ 007 View Post
Hi Rabbit. Happy new year!

So I finally set up my antenna (HD Stacker) on a 20' mast this week and the results were somewhat mixed. I was able to receive KNSD, KSWB, and KPBS however they are unwatchable with several drop outs every few minutes. KNSD is by far the most reliable among the three. My TV also picked up KFMB but it does not come in. On my TV's signal meter they range from no signal (about 40%) all the way up to 80% in some cases. The SNR read out on the screen ranges from 0 to up to 25. Here's a screen shot of what I've been typically receiving. Any thoughts?


Happy New Year!

The channels that you are able to receive are your strongest listed channels at your less than ideal OTA location.

Are you using a preamp?

Are the SD channels able to clear the peak of your roof?

Thank you for the photo. Fox looks good, but the SNR is just barley enough for a lock.



Since your signals are so weak and you have severe terrain interference, the only possible improvement I can think of is a little more UHF antenna gain if you are already using a preamp and the SD signals clear the roof. As I mentioned before, maybe the Antennas Direct 91XG or the Solid Signal HDB91X.

Some antenna locations on your lot might have stronger signals. It would be difficult to try another location, but you can try small changes in antenna height at the present location. Even a difference of 6" can make a difference in signal strength because multipath signals have a non-uniform wavefront.

Attached Thumbnails
Click image for larger version

Name:	MSZ 007AVS CH26_1.jpg
Views:	461
Size:	145.9 KB
ID:	2670344  

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; 01-15-2020 at 12:16 PM.
rabbit73 is online now  
post #17973 of 18330 Old 01-15-2020, 12:10 PM
Advanced Member
 
Join Date: Oct 2016
Location: Cleveland
Posts: 815
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 475 Post(s)
Liked: 53
Quote:
Originally Posted by labjr View Post
Thanks,

I saw a comment by Antennas Direct Tech support, which I can't find now, that said the Max-V was the same antenna as the 2Max. I bought a 2MAX at Walmart on clearance. But I still want to build one and compare. Replicating the balun is the difficult part.

Also Alibaba has a couple antennas that look like Clearstream antennas.
Also note that Antennas Direct is acquiring Mohu:

https://www.nexttv.com/news/top-ota-...rect-buys-mohu
jkeldo is offline  
Sponsored Links
Advertisement
 
post #17974 of 18330 Old 01-16-2020, 01:39 PM
Member
 
MSZ 007's Avatar
 
Join Date: Jan 2006
Location: Temecula, CA
Posts: 21
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 14 Post(s)
Liked: 10
Thanks for getting back to me Rabbit.

To answer your questions, I set up my antenna at about 20' on a push up style mast so it was able to clear my roof's peak when pointed to the south. I'm currently using a preamp which is a Channel Master 7778 Titan 2. I recently noticed the 7778 model was not meant for fringe areas. Do you think if I got the 7777 model would there be an improvement? I'm thinking not since my cabling for my tests is very simple. Its just a 75' coax from the preamp straight into the back of my TV. Once I get things dialed in, I plan on using the prewired coax through the house which has more connections, etc.

I noticed the signal goes out once the SNR is at 15 on my TV so yeah 17 is cutting it close. I've decided to return the HD Stacker and will give the AD 91XG a try. Also, I'm not tied to keeping my mast to the north side of my house. I could put it on the south side of the house and see what I get there. The house to the south of me is also a one story and its roof is lower in elevation than mine. The only hurdle is the two story two houses over. It's also lower but its peak is a little higher than my neighbor. Above that, it's a clear shot to the south with no trees.

My only issue is that I don't have a good way of supporting my mast with guy wires. It can only be mounted to my facia and the base with a ground mount. The fascia at the edge of my roof is about 9' high so if I have a 20' mast, 11' feet above would be unsupported. I have a concrete tile roof and don't want to mount anything (guy wires, struts, bracing, etc) to it. So ideally I'd like to just get away with a mast that's self supporting or maybe go with a larger diameter pipe.

Good to know on the multipath issues. I'm pretty sure that's what I'm experiencing since the signal fluctuates quite a bit. Slightly changing the antenna's angle from side to side did not help much so I'll try raising/lowering it in small increments next time. I'll definitely give that a try once the 91XG arrives.
MSZ 007 is offline  
post #17975 of 18330 Old 01-16-2020, 05:12 PM
AVS Forum Special Member
 
Calaveras's Avatar
 
Join Date: Jan 2007
Location: Hereford, AZ
Posts: 6,070
Mentioned: 21 Post(s)
Tagged: 0 Thread(s)
Quoted: 1799 Post(s)
Liked: 429
Quote:
Originally Posted by MSZ 007 View Post
I'm currently using a preamp which is a Channel Master 7778 Titan 2. I recently noticed the 7778 model was not meant for fringe areas. Do you think if I got the 7777 model would there be an improvement? I'm thinking not since my cabling for my tests is very simple. Its just a 75' coax from the preamp straight into the back of my TV. Once I get things dialed in, I plan on using the prewired coax through the house which has more connections, etc.

I don't know where you read that the 7778 is not for fringe areas and the 7777 is. There really is no such distinction. The required preamp gain is determined by how much loss you have between the antenna and the TV. With your basic setup the 7778 gain is fine, fringe area or not. If you get to using your pre-wired coax you'll need to estimate how much total loss there is. If you have strong signals a preamp is not required and can make things worse.

Your SNR of 17 dB is too low in most situations for reliable reception. I like to see at least 20 dB for some headroom and mid 20's is better.
Calaveras is offline  
post #17976 of 18330 Old 01-16-2020, 05:17 PM
AVS Forum Special Member
 
rabbit73's Avatar
 
Join Date: Apr 2008
Location: S.E. VA
Posts: 3,498
Mentioned: 23 Post(s)
Tagged: 0 Thread(s)
Quoted: 1009 Post(s)
Liked: 450
Quote:
Originally Posted by MSZ 007 View Post
To answer your questions, I set up my antenna at about 20' on a push up style mast so it was able to clear my roof's peak when pointed to the south. I'm currently using a preamp which is a Channel Master 7778 Titan 2. I recently noticed the 7778 model was not meant for fringe areas. Do you think if I got the 7777 model would there be an improvement? I'm thinking not since my cabling for my tests is very simple. Its just a 75' coax from the preamp straight into the back of my TV. Once I get things dialed in, I plan on using the prewired coax through the house which has more connections, etc.
Thank you for the update. The 7778 should be sufficient for that length of coax. If the signals are too weak after splitting, you can add a distribution amp. If you do get a 7777, don't get version 2 with a single antenna input and 30 dB gain; it's not reliable. The new 7777V3 is unproven, but I think it will be more reliable.



Quote:
I'm not tied to keeping my mast to the north side of my house. I could put it on the south side of the house and see what I get there. The house to the south of me is also a one story and its roof is lower in elevation than mine. The only hurdle is the two story two houses over. It's also lower but its peak is a little higher than my neighbor.
It is possible that the signals are better on the south side of your house, but I think it would be better to stay on the north side back from the two story two houses over.

Quote:
My only issue is that I don't have a good way of supporting my mast with guy wires. It can only be mounted to my facia and the base with a ground mount. The fascia at the edge of my roof is about 9' high so if I have a 20' mast, 11' feet above would be unsupported. I have a concrete tile roof and don't want to mount anything (guy wires, struts, bracing, etc) to it. So ideally I'd like to just get away with a mast that's self supporting or maybe go with a larger diameter pipe.
I agree.
Quote:
Good to know on the multipath issues. I'm pretty sure that's what I'm experiencing since the signal fluctuates quite a bit. Slightly changing the antenna's angle from side to side did not help much so I'll try raising/lowering it in small increments next time. I'll definitely give that a try once the 91XG arrives.
I hope you will see an improvement with the 91XG. Your desired signals are rated as Tropo, so they will never be 100% reliable.

https://www.rabbitears.info/searchma...study_id=30021









johnny antenna likes this.

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; 01-16-2020 at 06:26 PM.
rabbit73 is online now  
post #17977 of 18330 Old 01-16-2020, 05:23 PM
AVS Forum Special Member
 
Calaveras's Avatar
 
Join Date: Jan 2007
Location: Hereford, AZ
Posts: 6,070
Mentioned: 21 Post(s)
Tagged: 0 Thread(s)
Quoted: 1799 Post(s)
Liked: 429
Quote:
Originally Posted by MSZ 007 View Post
My only issue is that I don't have a good way of supporting my mast with guy wires. It can only be mounted to my facia and the base with a ground mount. The fascia at the edge of my roof is about 9' high so if I have a 20' mast, 11' feet above would be unsupported. I have a concrete tile roof and don't want to mount anything (guy wires, struts, bracing, etc) to it. So ideally I'd like to just get away with a mast that's self supporting or maybe go with a larger diameter pipe.
The solution to this is get a couple of Rohn 25 tower sections. See attached image. The short tower is a rock and provides an easy and safer way than a ladder to get up on the roof.
Attached Thumbnails
Click image for larger version

Name:	TV_Antennas1.jpg
Views:	47
Size:	306.1 KB
ID:	2671040  
Calaveras is offline  
post #17978 of 18330 Old 01-16-2020, 05:44 PM
Member
 
statmanmi's Avatar
 
Join Date: Nov 2017
Posts: 71
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 45 Post(s)
Liked: 16
Mast/mount ideas

Quote:
Originally Posted by MSZ 007 View Post
My only issue is that I don't have a good way of supporting my mast with guy wires. It can only be mounted to my facia and the base with a ground mount. The fascia at the edge of my roof is about 9' high so if I have a 20' mast, 11' feet above would be unsupported. I have a concrete tile roof and don't want to mount anything (guy wires, struts, bracing, etc) to it. So ideally I'd like to just get away with a mast that's self supporting or maybe go with a larger diameter pipe.
Hi MSZ 007,

I'll offer some unproven-by-me mast mounting thoughts from my novice mind--although I've been reading lots of other people's posts in the last 3 years. In my case, the home I own now came with a tripod antenna mount on the garage roof. But the time will come when the asphalt shingles will need to be replaced, and it has me thinking that I may want to go with a fascia mount along the peak at the end of the structure. Thus, similar to what I'm perceiving your thoughts to be.

The rule of thumb I've read is that the maximum unsupported mast height (thus, without guy wires) is 10 feet. With a concern then that if one is in a windy area, 10 feet might allow for too much sway in the mast.

This YouTube caught my eye recently:

Two thoughts that the gentleman expressed were:

* He has the mast 3 feet deep in the ground.
* The antenna is within reach when he stands on the roof--he mentions being 7 feet above the peak.

My best guess is that 3 feet in the ground should be the minimum. Seems like 4 feet would match the length some antenna ground rods are made.

With those ideas, I'd revisit your hypothetical that 20 feet of mast would provide you 11 feet of (unsupported) clearance. For that, I'm picturing you weren't going to bury any of the mast in the ground. If instead you go with 20 feet total, consider having 7 feet above the peak of the roof, which will allow you to bury 4 feet below ground level (using your 9 foot roof height mentioned above).

I might be all wet with these thoughts. Perhaps someone with past hands-on experience will share further ideas.


Also, for a fascia mount, this YouTube came up in my search:

I tracked down the business's website to be: https://antennaservicesinc.com/

In the video, the narrator mentions about how their design has the two U-bolts to better stabilize than a single one that could slide some with the mast. That also sounds good to novice me. Not an endorsement of this particular product by any means, just a further thought that has me thinking.

Good luck! ~~ Statmanmi
johnny antenna likes this.

Kent County, MI
statmanmi is offline  
post #17979 of 18330 Old 01-16-2020, 06:02 PM
AVS Forum Special Member
 
Calaveras's Avatar
 
Join Date: Jan 2007
Location: Hereford, AZ
Posts: 6,070
Mentioned: 21 Post(s)
Tagged: 0 Thread(s)
Quoted: 1799 Post(s)
Liked: 429
Quote:
Originally Posted by rabbit73 View Post



I don't think this overlapping rays problem gets as much attention as it deserves. Comparing my old location where the ridge with overlapping rays was 1/2 mile away and my new location where the ridge is 34 miles away, it appears that moving the antenna when the ridge is close by can significantly impact the SNR while there's no change with the distant ridge.

Here at my new location I have a channel 30 and a channel 32 that are roughly the same strength from the same transmitter site. The channel 30 SNR rarely goes above 24 dB while the channel 32 SNR never budges from 31 dB. Antennas as much as 100' apart show no change. The antenna used makes no difference either.

At my old location with the 1/2 mile away ridge, antennas 90' apart showed large differences in SNR between the two. Different antennas didn't show any difference.

The XG91 made a big improvement if the multipath was coming from the rear but made no difference if the multipath was coming from overlapping rays.
johnny antenna likes this.
Calaveras is offline  
post #17980 of 18330 Old 01-17-2020, 07:23 AM
AVS Forum Special Member
 
Calaveras's Avatar
 
Join Date: Jan 2007
Location: Hereford, AZ
Posts: 6,070
Mentioned: 21 Post(s)
Tagged: 0 Thread(s)
Quoted: 1799 Post(s)
Liked: 429
Quote:
Originally Posted by statmanmi View Post

* The antenna is within reach when he stands on the roof--he mentions being 7 feet above the peak.

My best guess is that 3 feet in the ground should be the minimum. Seems like 4 feet would match the length some antenna ground rods are made.

I don't think burying a galvanized steel mast 3' in the ground is a very good idea. It will eventually rust being in permanent contact with damp soil. In 50 years every mast or tower installation I have seen has been insulated from direct contact with the ground. Even a simple post hole type base for a galvanized steel pipe filled with concrete needs to have the bottom filled with a few inches of rock to prevent direct soil contact and facilitate drainage.

For a mast with eave brackets there's no reason for the mast to be 3' in the ground. The point at which the base is secured to the ground only prevents the base from kicking out. It doesn't have to be far in the ground to do that. Instead of burying the mast, it's much better to dig a small hole, perhaps 1' square and 1' deep and poor concrete. A couple 60 lb bags of Quikcrete will do the trick. After it's dry, drill a couple of holes for a mast base and secure it with lag bolts and expansion anchors.

Attached is an image of the base for my 20' TV antenna tower. The concrete is about 6" deep and 2 foot square. I used 3 lag bolts and expander anchors to secure the base to the concrete base. The ground rod is 8'.

Here are a couple of base solutions for Rohn Push-up masts.

https://www.dxengineering.com/parts/roh-gtmbl

https://www.dxengineering.com/parts/roh-um50
Attached Thumbnails
Click image for larger version

Name:	TV_Antenna_Grounding+Base_Support.jpg
Views:	57
Size:	1,000.5 KB
ID:	2671238  
richart and johnny antenna like this.

Last edited by Calaveras; 01-17-2020 at 01:27 PM.
Calaveras is offline  
post #17981 of 18330 Old 01-17-2020, 08:55 AM
Senior Member
 
richart's Avatar
 
Join Date: Apr 2010
Posts: 395
Mentioned: 4 Post(s)
Tagged: 1 Thread(s)
Quoted: 209 Post(s)
Liked: 94
Quote:
Originally Posted by statmanmi View Post
Two thoughts that the gentleman expressed were:

* He has the mast 3 feet deep in the ground.
* The antenna is within reach when he stands on the roof--he mentions being 7 feet above the peak.

My best guess is that 3 feet in the ground should be the minimum. Seems like 4 feet would match the length some antenna ground rods are made.
Gosh, I really don't like the idea of burying a mast of any type in the ground or in concrete...the thin metal will deteriorate over time. I have a 30 ft galvanized push-up mast. I use a commercial ground mount. The plate portion of the mount effectively supports the weight of the mast and the post prohibits the mast from moving laterally. My mast is also bracketed at the eaves of the house and has a set of black dacron rope guys at the top. It has been up for several years with no problems and supports a large UHF and a large Hi-VHF antenna.
Attached Thumbnails
Click image for larger version

Name:	z.jpg
Views:	38
Size:	58.3 KB
ID:	2671314  
johnny antenna likes this.
richart is offline  
post #17982 of 18330 Old 01-17-2020, 12:59 PM
AVS Forum Special Member
 
rabbit73's Avatar
 
Join Date: Apr 2008
Location: S.E. VA
Posts: 3,498
Mentioned: 23 Post(s)
Tagged: 0 Thread(s)
Quoted: 1009 Post(s)
Liked: 450
New amp from Channel Master
https://www.channelmaster.com/MicroA..._p/cm-7776.htm



The MicroAmp is included with the FLATenna+ Amplified indoor TV antenna:
https://www.channelmaster.com/FLATen...-4001hdbwa.htm
Attached Thumbnails
Click image for larger version

Name:	CM 7776 MicroAmp.JPG
Views:	473
Size:	90.4 KB
ID:	2671504  

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; 01-17-2020 at 01:16 PM.
rabbit73 is online now  
post #17983 of 18330 Old 01-17-2020, 07:32 PM
AVS Forum Special Member
 
tylerSC's Avatar
 
Join Date: Jun 2010
Location: Mauldin SC, 29607
Posts: 6,883
Mentioned: 4 Post(s)
Tagged: 1 Thread(s)
Quoted: 1440 Post(s)
Liked: 272
Quote:
Originally Posted by rabbit73 View Post
New amp from Channel Master
https://www.channelmaster.com/MicroA..._p/cm-7776.htm



The MicroAmp is included with the FLATenna+ Amplified indoor TV antenna:
https://www.channelmaster.com/FLATen...-4001hdbwa.htm
Supposed to be for use with an indoor antenna but seems like noise figure may be a bit high. Less than 2.0db is usually considered better.
tylerSC is online now  
post #17984 of 18330 Old 01-19-2020, 06:03 AM
AVS Forum Special Member
 
CHASLS2's Avatar
 
Join Date: Feb 2009
Location: Tampa FL area
Posts: 3,223
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 1129 Post(s)
Liked: 501
Quote:
Originally Posted by richart View Post
Gosh, I really don't like the idea of burying a mast of any type in the ground or in concrete...the thin metal will deteriorate over time. I have a 30 ft galvanized push-up mast. I use a commercial ground mount. The plate portion of the mount effectively supports the weight of the mast and the post prohibits the mast from moving laterally. My mast is also bracketed at the eaves of the house and has a set of black dacron rope guys at the top. It has been up for several years with no problems and supports a large UHF and a large Hi-VHF antenna.
I have had one stuck in the ground for 40 years and it is still fine as wine. But it is very thick wall pipe about 3mm thick.

Sony 65" A1E Pioneer Elite DV-59 AVI
OPPO203,103&83 Sony BD player
Pioneer Elite SC61 AVR Acurus 200x 3
Paradigm 60V5'S 490 CC V5
B&W 685 S2's 2 SVS subs
CHASLS2 is offline  
post #17985 of 18330 Old 01-20-2020, 07:14 AM
AVS Forum Special Member
 
tylerSC's Avatar
 
Join Date: Jun 2010
Location: Mauldin SC, 29607
Posts: 6,883
Mentioned: 4 Post(s)
Tagged: 1 Thread(s)
Quoted: 1440 Post(s)
Liked: 272
Quote:
Originally Posted by rabbit73 View Post
Antennas Direct posted this reply for their video:
Looks like the placement of the VHF dipole may be slightly different, but the UHF loops may be the same. And the 2MAX comes with an indoor stand, but the MAX-V does not; it must be purchased separately.
tylerSC is online now  
post #17986 of 18330 Old 01-20-2020, 07:24 AM
Member
 
labjr's Avatar
 
Join Date: Feb 2006
Posts: 59
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 15 Post(s)
Liked: 10
Quote:
Originally Posted by tylerSC View Post
Looks like the placement of the VHF dipole may be slightly different, but the UHF loops may be the same. And the 2MAX comes with an indoor stand, but the MAX-V does not; it must be purchased separately.
Looking at my 2MAX, I noticed the dipole is a separate assembly which the UHF loops assembly plugs into. Thus it appears the loops and dipole each have their own balun and signals are combined in the dipole assembly. Not sure how it's done in the MAX-V?
labjr is offline  
post #17987 of 18330 Old 01-20-2020, 08:51 AM
AVS Forum Special Member
 
rabbit73's Avatar
 
Join Date: Apr 2008
Location: S.E. VA
Posts: 3,498
Mentioned: 23 Post(s)
Tagged: 0 Thread(s)
Quoted: 1009 Post(s)
Liked: 450
Quote:
Originally Posted by labjr View Post
Looking at my 2MAX, I noticed the dipole is a separate assembly which the UHF loops assembly plugs into. Thus it appears the loops and dipole each have their own balun and signals are combined in the dipole assembly. Not sure how it's done in the MAX-V?
The VHF dipole has no direct connection; its signals are picked up on the UHF loops by capacitive coupling like the NARODS for VHF on the Gray-Hoverman antenna.

my post:

https://www.avsforum.com/forum/25-hd...l#post59102798


If you can not measure it, you can not improve it.
Lord Kelvin, 1883
www.megalithia.com/elect/aerialsite/dttpoorman.html
rabbit73 is online now  
post #17988 of 18330 Old 01-20-2020, 09:38 AM
Member
 
labjr's Avatar
 
Join Date: Feb 2006
Posts: 59
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 15 Post(s)
Liked: 10
I saw your earlier post. I thought you were speculating about the capacitive coupling? Do you know if anyone has confirmed this to be true?
labjr is offline  
post #17989 of 18330 Old 01-20-2020, 09:55 AM
AVS Forum Special Member
 
rabbit73's Avatar
 
Join Date: Apr 2008
Location: S.E. VA
Posts: 3,498
Mentioned: 23 Post(s)
Tagged: 0 Thread(s)
Quoted: 1009 Post(s)
Liked: 450
Quote:
Originally Posted by labjr View Post
I saw your earlier post. I thought you were speculating about the capacitive coupling? Do you know if anyone has confirmed this to be true?
I have been doing antenna experiments since I was 8; I'm now 86. I have built and tested many ham and TV antennas, so let's call it an educated guess. If it isn't what I say it is, how do you think the VHF signals from the dipole get to the feedline?

The only person I know that can confirm it is forum member ADTech, who works for Antennas Direct. Maybe he will see this and give an answer.





https://www.digitalhome.ca/forum/186...ion-narod.html



The concept is described by Gary Breed in his patent
US5489914A

METHOD OF CONSTRUCTING MULTIPLE-FREQUENCY DIPOLE OR MONOPOLE
ANTENNA ELEMENTS USING CLOSELY COUPLED RESONATORS

He uses the terms closely coupled and electromagnetically coupled. I have used the term capacitive coupling because the ends of the elements (high voltage, low current) are close together. If only the centers of the elements (high current, low voltage) were close together, the coupling would be primarily inductive, as described by Les Moxon G6XN in his book HF Antennas for all Locations. The ends of the elements (high voltage, low current) in the Moxon Rectangle antenna are capacitively coupled. The safest general term would be electromagnetically coupled. The spacing determines the amount of coupling.

Attached Thumbnails
Click image for larger version

Name:	AD MAX-V Parts.JPG
Views:	360
Size:	123.6 KB
ID:	2672742   Click image for larger version

Name:	AD MAX-V Dipole.JPG
Views:	351
Size:	102.8 KB
ID:	2672744   Click image for larger version

Name:	Gray-Hoverman Antenna with NARODS2.jpg
Views:	349
Size:	76.2 KB
ID:	2672788   Click image for larger version

Name:	Closely Coupled Resonator-Gary Breed2.jpg
Views:	308
Size:	71.8 KB
ID:	2673030  

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; 01-21-2020 at 12:16 PM.
rabbit73 is online now  
post #17990 of 18330 Old 01-20-2020, 10:20 AM
Member
 
labjr's Avatar
 
Join Date: Feb 2006
Posts: 59
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 15 Post(s)
Liked: 10
You're the same age my dad would've been! He was also a ham.

If that's true then this would appear to be easier to replicate than the 2MAX. Now I'm wondering exactly how the coupling was done? Just need to see a teardown.
labjr is offline  
post #17991 of 18330 Old 01-21-2020, 08:15 AM
Member
 
Steve347's Avatar
 
Join Date: Jan 2010
Posts: 37
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 40 Post(s)
Liked: 2
REPACK OPTIMIZED ANTENNAS?

Has anyone seen or heard mention of any repack optimized antennas? I would think that the repack would make them physically slightly larger that current designs. Too bad the repack frequencies didn't go the other way or all you would need would be a pair of wire cutters/hacksaw!
Steve347 is offline  
post #17992 of 18330 Old 01-21-2020, 08:22 AM
AVS Forum Special Member
 
rabbit73's Avatar
 
Join Date: Apr 2008
Location: S.E. VA
Posts: 3,498
Mentioned: 23 Post(s)
Tagged: 0 Thread(s)
Quoted: 1009 Post(s)
Liked: 450
Quote:
Originally Posted by Steve347 View Post
REPACK OPTIMIZED ANTENNAS?

Has anyone seen or heard mention of any repack optimized antennas? I would think that the repack would make them physically slightly larger that current designs. Too bad the repack frequencies didn't go the other way or all you would need would be a pair of wire cutters/hacksaw!
Forum member holl_ands, who does computer modeling of antennas, has done a few designs for the DIYer.

https://imageevent.com/holl_ands

https://imageevent.com/holl_ands/multibay

New UHF Spectrum antennas?
https://www.digitalhome.ca/forum/186-antenna-research-development/288187-new-uhf-spectrum-antennas.html

majortom's post of design for new UHF band:
https://www.digitalhome.ca/forum/186...ml#post3098283

Attached Thumbnails
Click image for larger version

Name:	majortomDHCfat8bay4.JPG
Views:	264
Size:	110.9 KB
ID:	2673524  

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; 01-21-2020 at 10:12 AM.
rabbit73 is online now  
post #17993 of 18330 Old 01-21-2020, 08:40 AM
Member
 
Steve347's Avatar
 
Join Date: Jan 2010
Posts: 37
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 40 Post(s)
Liked: 2
Quote:
Originally Posted by rabbit73 View Post
Forum member holl_ands, who does computer modeling of antennas, has done a few designs for the DIYer.

https://imageevent.com/holl_ands

https://imageevent.com/holl_ands/multibay

New UHF Spectrum antennas?
https://www.digitalhome.ca/forum/186...-antennas.html
Thanks for the info. I was hoping (and waiting) for a commercial solution since this will end up outside on top of the house exposed to the elements.
Steve347 is offline  
post #17994 of 18330 Old 01-21-2020, 08:50 AM
AVS Forum Special Member
 
rabbit73's Avatar
 
Join Date: Apr 2008
Location: S.E. VA
Posts: 3,498
Mentioned: 23 Post(s)
Tagged: 0 Thread(s)
Quoted: 1009 Post(s)
Liked: 450
Quote:
Originally Posted by Steve347 View Post
Thanks for the info. I was hoping (and waiting) for a commercial solution since this will end up outside on top of the house exposed to the elements.
You are going to have to wait a long time for any manufacturer to make a UHF antenna optimized for 14 to 36. As of now, there are only a few designs for the 14-51 UHF band. The Antennas Direct DB8e and DB4e were optimized for 14 to 51.

No manufacturer is going to produce an antenna for 14-36 unless they think they can make a profit on it.

The closest I know of is the XB16A yagi from the UK for their 21 to 37, which is approx equal to our 14-37:



A yagi has a steeply rising gain curve; the gain curve for a bowtie antenna would be flatter which would give more gain at the low end.

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; 01-21-2020 at 09:00 AM.
rabbit73 is online now  
post #17995 of 18330 Old 01-21-2020, 08:52 AM
Member
 
labjr's Avatar
 
Join Date: Feb 2006
Posts: 59
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 15 Post(s)
Liked: 10
If the FCC repack is taking OTA spectrum, why would current antenna designs need to be modified? Are they moving stations to new part of the spectrum?

Maybe someone can point to a detailed explanation with cool graphs etc.? A search seems to turn up only basic simple explanations of the process.
labjr is offline  
post #17996 of 18330 Old 01-21-2020, 08:58 AM
Member
 
labjr's Avatar
 
Join Date: Feb 2006
Posts: 59
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 15 Post(s)
Liked: 10
Quote:
Originally Posted by rabbit73 View Post
You are going to have to wait a long time for any manufacturer to make a UHF antenna optimized for 14 to 36. As of now, there are only a few designs for the 14-51 UHF band. The Antennas Direct DB8e and DB4e were optimized for 14 to 51.


No manufacturer is going to produce an antenna for 14-36 unless they think they can make a profit on it.
So everything above 36 has been taken for 5G! That isn't right! Eventually, corporations will be coming for the rest of the public airwaves!

Last edited by labjr; 01-21-2020 at 09:05 AM.
labjr is offline  
post #17997 of 18330 Old 01-21-2020, 10:40 AM
Member
 
Steve347's Avatar
 
Join Date: Jan 2010
Posts: 37
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 40 Post(s)
Liked: 2
Quote:
Originally Posted by rabbit73 View Post
You are going to have to wait a long time for any manufacturer to make a UHF antenna optimized for 14 to 36. As of now, there are only a few designs for the 14-51 UHF band. The Antennas Direct DB8e and DB4e were optimized for 14 to 51.

No manufacturer is going to produce an antenna for 14-36 unless they think they can make a profit on it.
I guess that this brings up another question... What kind of performance increase could be expected if the design was optimized for 14-36 vs. 14-51?

BTW, Looks like AD is blowing out DB4Es at $60 including shipping. Don't know if this is a good deal or not?
Steve347 is offline  
post #17998 of 18330 Old 01-21-2020, 10:45 AM
AVS Forum Special Member
 
rabbit73's Avatar
 
Join Date: Apr 2008
Location: S.E. VA
Posts: 3,498
Mentioned: 23 Post(s)
Tagged: 0 Thread(s)
Quoted: 1009 Post(s)
Liked: 450
Quote:
Originally Posted by labjr View Post
If the FCC repack is taking OTA spectrum, why would current antenna designs need to be modified?
The current designs would need to be modified to give more gain at the low end of UHF. The gain curve of a UHF antenna is not constant at all frequencies; it rises as the frequency increases. The max gain of the current designs is above channel 36. If you make the antenna a little larger, this will move the peak of the gain curve down in frequency.



Quote:
Are they moving stations to new part of the spectrum?

Maybe someone can point to a detailed explanation with cool graphs etc.? A search seems to turn up only basic simple explanations of the process.
Yes, the previous 14-51 for UHF TV has been reduced to 14-36. The cellular interests wanted more spectrum, so they went to congress. Congress said sure, and ordered the FCC to hold a reverse auction which took 38 to 51 away from TV broadcast and gave it to the cellular interests. Channel 37 is reserved for other services, like radio astronomy. The TV broadcasters using 38 to 51 were offered payment to surrender their license, move to 14-36, or move to VHF.

If you can not measure it, you can not improve it.
Lord Kelvin, 1883
www.megalithia.com/elect/aerialsite/dttpoorman.html
rabbit73 is online now  
post #17999 of 18330 Old 01-21-2020, 10:48 AM
AVS Forum Special Member
 
rabbit73's Avatar
 
Join Date: Apr 2008
Location: S.E. VA
Posts: 3,498
Mentioned: 23 Post(s)
Tagged: 0 Thread(s)
Quoted: 1009 Post(s)
Liked: 450
Quote:
Originally Posted by labjr View Post
So everything above 36 has been taken for 5G! That isn't right! Eventually, corporations will be coming for the rest of the public airwaves!
They will probably try.

If you can not measure it, you can not improve it.
Lord Kelvin, 1883
www.megalithia.com/elect/aerialsite/dttpoorman.html
rabbit73 is online now  
post #18000 of 18330 Old 01-21-2020, 10:59 AM
AVS Forum Special Member
 
rabbit73's Avatar
 
Join Date: Apr 2008
Location: S.E. VA
Posts: 3,498
Mentioned: 23 Post(s)
Tagged: 0 Thread(s)
Quoted: 1009 Post(s)
Liked: 450
Quote:
Originally Posted by Steve347 View Post
I guess that this brings up another question... What kind of performance increase could be expected if the design was optimized for 14-36 vs. 14-51?

BTW, Looks like AD is blowing out DB4Es at $60 including shipping. Don't know if this is a good deal or not?


The increase in gain at the low end of UHF would be dramatic as the peak of the gain curve moves down in frequency to the left when the antenna is made larger. The size of the elements is increased as you lower the frequency, just like organ pipes must be longer for the low notes.

The DB4e is an excellent UHF antenna. It would be a good deal if it is the right antenna for your location.

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; 01-21-2020 at 12:09 PM.
rabbit73 is online now  
Sponsored Links
Advertisement
 
Reply HDTV Technical

Tags
Channel Master Cm 4228 8 Bay Hdtv Uhf Antenna Cm4228hd

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