Re: Topband: NVIS Antenna
Roger, I think you're observations propagation are correct, but I strongly disagree with the paragraph below. My experience has been that IF the antenna is accurately modeled, ground characteristics accurately represent where the antenna is rigged, and the appropriate NEC ground model is selected, modelling WILL correctly predict it's performance over FLAT terrain. It's well known that non-flat terrain has major effects on horizontally polarized waves, and N6BT has recently published his work showing that it also strongly affects vertically polarized waves. 73, Jim K9YC On 3/16/2020 5:52 AM, Roger Kennedy wrote: The only other factor I DO think is that if you have a low dipole on 160m but DON'T have any radials or anything underneath it, it probably radiates more low angle than computer-modelling software would suggest. I believe the errors occur on 160m because it can't properly forecast the effect of the REAL WORLD ground when the antenna is a fraction of a wavelength above it. _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: NVIS Antenna
I fully agree with the statements below. *Most* of the time, a vertical is superior for DX on 160m. Please see: https://web.archive.org/web/20170703105635/http://www.w0btu.com/160_meters.html 73, Mike W0BTU On Mon, Mar 16, 2020, 7:52 AM Roger Kennedy wrote: > > ... DX propagation on 160m ISN'T like 80m (where it IS nearly all low > angle, so you MUST have a good vertical to work DX effectively) ... Most of > the "experts" who have written books about Low-band DX-ing have made the > assumption that 160m is just like 80m . . . which in my experience it > clearly isn't ! ... > _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: NVIS Antenna
There is nothing special, a 50 feet high dipole has at 25° elevation angle the same gain as a shortened vertical over lossy ground or with just a few radials. 73 Peter -Original Message- From: Topband [mailto:topband-bounces+dj7ww=t-online...@contesting.com] On Behalf Of Roger Kennedy Sent: Montag, 16. März 2020 13:52 To: topband@contesting.com Subject: Topband: NVIS Antenna Well I've said it dozens of times before . . . but I have used a horizontal halfwave Dipole (at about 50ft) for working DX on 160m for the past 50 years ! (and that's at 6 different QTHs) Not only do I work all over the world, but I know my signal often compares pretty well with other Gs using good verticals . . . and I have no problem getting through the pile-ups working the various DX-peditions. How is this possible? Well in my opinion it's because DX propagation on 160m ISN'T like 80m (where it IS nearly all low angle, so you MUST have a good vertical to work DX effectively) Based on the hundreds of comparison QSOs I've had over the decades, I figure that on 160m, propagation MUST be fairly high angle a lot of the time, presumably because of inter-layer reflections or ducting. Most of the "experts" who have written books about Low-band DX-ing have made the assumption that 160m is just like 80m . . . which in my experience it clearly isn't ! The only other factor I DO think is that if you have a low dipole on 160m but DON'T have any radials or anything underneath it, it probably radiates more low angle than computer-modelling software would suggest. I believe the errors occur on 160m because it can't properly forecast the effect of the REAL WORLD ground when the antenna is a fraction of a wavelength above it. Roger G3YRO _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Topband: NVIS Antenna
Well I've said it dozens of times before . . . but I have used a horizontal halfwave Dipole (at about 50ft) for working DX on 160m for the past 50 years ! (and that's at 6 different QTHs) Not only do I work all over the world, but I know my signal often compares pretty well with other Gs using good verticals . . . and I have no problem getting through the pile-ups working the various DX-peditions. How is this possible? Well in my opinion it's because DX propagation on 160m ISN'T like 80m (where it IS nearly all low angle, so you MUST have a good vertical to work DX effectively) Based on the hundreds of comparison QSOs I've had over the decades, I figure that on 160m, propagation MUST be fairly high angle a lot of the time, presumably because of inter-layer reflections or ducting. Most of the "experts" who have written books about Low-band DX-ing have made the assumption that 160m is just like 80m . . . which in my experience it clearly isn't ! The only other factor I DO think is that if you have a low dipole on 160m but DON'T have any radials or anything underneath it, it probably radiates more low angle than computer-modelling software would suggest. I believe the errors occur on 160m because it can't properly forecast the effect of the REAL WORLD ground when the antenna is a fraction of a wavelength above it. Roger G3YRO _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: NVIS Antenna
Back in 2017 I put up a 160M Inverted V with the apex at about 35' and the ends at 8' with the only goal being to try inband SO2R on 160M. My reasoning was the V "should" be able to work stations out to ~500Km ( 300 Miles ) and more importantly hold my run QRG while I went up the band to S for Mults with the second radio and my "real" antenna ( Inverted L with 105' vertical and with >20,000' of radials ). To my amazement I was getting RBN hits from coast to coast in NA as well as the northern part of SA. The reports were on average about 10db - 15db lower than my TX vertical "but" I was still being heard. So in the 2018 and 2019 CQ160 CW and ARRL 160 contests I was SO2R and both years I was called by stations from as close as 100 km to as far as the West coast of NA ( ~3,500 km ), and as far south as the Southern Caribbean ( also ~3,500 km ) on the low Inverted V. So not only did it hold my QRG but it worked a lot better than I had thought it would beforehand. Then on 2018-03-27 at 11:10z ( SR -4 min ) I even worked VK3HJ ( thanks Luke ) 16,116 km away with it as well so as Carl says "it's better than no antenna". Also that QSO was most likely ducting propagation as it only happened after I had lost all of Luke's signal on my vertical and then switched over to the V where he was Q5 and ~S3. All the above was done with 100 watts so if you ( or I ) had run legal limit power the results would have been even better. FYI I am no longer doing inband SO2R on 160 ( or any other band ) after having too many close calls with frying a front end. So caveat emptor if you try it. 73, Brian VE3MGY From: Topband on behalf of Carl Luetzelschwab Sent: March 15, 2020 3:47 PM To: topBand List Subject: Re: Topband: NVIS Antenna For those who are antenna challenged, don't sell a 160m inverted-vee at low height too short. My 160m antenna at the moment is an inverted-vee at an apex of 45 feet. Additionally, the last third of each end is at 90 degrees to the main portion and horizontal at only 7 feet or so off the ground. It's what fits on the property. In the CQ 160m CW contest in January 2017. I came away with 44 states (missed ME, ID, NE and AK), 7 Canadian provinces (VE9, VY2, VE2, VE3, VE5, VE6 and VE7) and 17 DXCC entities (mostly Caribbean, Central America, Mexico and South America, with a few Europeans, a North African and a KH6 in the mix). I was seldom #1 in a pile-up, but eventually I usually got through with 800 Watts to the inv-vee. It's better than no antenna. Carl K9LA _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: NVIS Antenna
Receive only comment. A low dipole - 15 feet average, uneven ground - Receive Only - accounted for something like 40% of the contacts with NA from XZ0A. During the first 2 hours at Sunset, the low dipole heard signals that the admittedly not all that good beverages could not hear at all. Site had a pretty good noise floor for Asia. on an island on Diesel power. This was during a higher portion of the sunspot cycle so the polar oval was quite large preventing most of NA from having a clean direct path. Our signal - 1500W into a elevated radial elevated feedpoint full size quarter wave tower - was invariably heard via the SW path when heard east of the Midwest. so we were dealing with ducting and greyline bending. the point is - again - you can never have too many receive antennas. An NVIS receive antenna can significantly benefit your receive capabilities. YMMV especially based on location. Equatorial regions seem to benefit more from NVIS RX and or Horizontal polarization. On Transmit it appears the ground absorption negates the benefits for longer haul paths where better efficiency is needed - until you get the dipole high enough to stop heating the gophers. Robin WA6CDR XZ0A-XZ1N, etc - Original Message - From: "Wes" To: Sent: Sunday, March 15, 2020 13:03 Subject: Re: Topband: NVIS Antenna When I decided on the new challenge of working DXCC on 160 for my ninth band, I added some extensions on my 80-meter inverted-vee , (apex at 45') and tied them off on some handy saguaro cacti about head high. You don't climb these :-) I worked my first 80 or so countries with it. And this is from southern AZ, not Maine. K3S + KPA500. Wes N7WS On 3/15/2020 12:47 PM, Carl Luetzelschwab wrote: For those who are antenna challenged, don't sell a 160m inverted-vee at low height too short. My 160m antenna at the moment is an inverted-vee at an apex of 45 feet. Additionally, the last third of each end is at 90 degrees to the main portion and horizontal at only 7 feet or so off the ground. It's what fits on the property. In the CQ 160m CW contest in January 2017. I came away with 44 states (missed ME, ID, NE and AK), 7 Canadian provinces (VE9, VY2, VE2, VE3, VE5, VE6 and VE7) and 17 DXCC entities (mostly Caribbean, Central America, Mexico and South America, with a few Europeans, a North African and a KH6 in the mix). I was seldom #1 in a pile-up, but eventually I usually got through with 800 Watts to the inv-vee. It's better than no antenna. Carl K9LA _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: NVIS Antenna
When I decided on the new challenge of working DXCC on 160 for my ninth band, I added some extensions on my 80-meter inverted-vee , (apex at 45') and tied them off on some handy saguaro cacti about head high. You don't climb these :-) I worked my first 80 or so countries with it. And this is from southern AZ, not Maine. K3S + KPA500. Wes N7WS On 3/15/2020 12:47 PM, Carl Luetzelschwab wrote: For those who are antenna challenged, don't sell a 160m inverted-vee at low height too short. My 160m antenna at the moment is an inverted-vee at an apex of 45 feet. Additionally, the last third of each end is at 90 degrees to the main portion and horizontal at only 7 feet or so off the ground. It's what fits on the property. In the CQ 160m CW contest in January 2017. I came away with 44 states (missed ME, ID, NE and AK), 7 Canadian provinces (VE9, VY2, VE2, VE3, VE5, VE6 and VE7) and 17 DXCC entities (mostly Caribbean, Central America, Mexico and South America, with a few Europeans, a North African and a KH6 in the mix). I was seldom #1 in a pile-up, but eventually I usually got through with 800 Watts to the inv-vee. It's better than no antenna. Carl K9LA _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: NVIS Antenna
For those who are antenna challenged, don't sell a 160m inverted-vee at low height too short. My 160m antenna at the moment is an inverted-vee at an apex of 45 feet. Additionally, the last third of each end is at 90 degrees to the main portion and horizontal at only 7 feet or so off the ground. It's what fits on the property. In the CQ 160m CW contest in January 2017. I came away with 44 states (missed ME, ID, NE and AK), 7 Canadian provinces (VE9, VY2, VE2, VE3, VE5, VE6 and VE7) and 17 DXCC entities (mostly Caribbean, Central America, Mexico and South America, with a few Europeans, a North African and a KH6 in the mix). I was seldom #1 in a pile-up, but eventually I usually got through with 800 Watts to the inv-vee. It's better than no antenna. Carl K9LA _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: NVIS Antenna
Inverted vee dipoles do produce some vertically polarized radiation off the ends. However, that vertical component has maximum gain at zenith, i.e. straight overhead. It does not contribute to any significant low-angle radiation. You can see this by doing an antenna model. 73, John W1FV -Original Message- From: Topband [mailto:topband-bounces+john.kaufmann=verizon@contesting.com] On Behalf Of Jim Brown Sent: Sunday, March 15, 2020 2:36 PM To: topband@contesting.com Subject: Re: Topband: NVIS Antenna Hi Ed, I've studied this extensively for horizontally polarized antennas, but only for flat ones; I thin that inverted Vees have some vertical components. For horizontally polarized antennas, maximum gain at high angles occurs at a mounting height of about 75 electrical degrees, and falls by only about 1 dB if raised to 120 electrical degrees. By "high," I'm talking 70 degrees elevation. Also, RX is different from TX, in that with RX we don't care about loss, only signal to noise. Ground loss is a contributor to those variations based on mounting height. N6RO, an old hand on topband with a great antenna farm, rearranges his M/6 station for topband contests to bring LOTS of his antennas to the station he uses single-op. That study is here. http://k9yc.com/AntennaPlanning.pdf 73, Jim K9YC _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: NVIS Antenna
Hi Ed, I've studied this extensively for horizontally polarized antennas, but only for flat ones; I thin that inverted Vees have some vertical components. For horizontally polarized antennas, maximum gain at high angles occurs at a mounting height of about 75 electrical degrees, and falls by only about 1 dB if raised to 120 electrical degrees. By "high," I'm talking 70 degrees elevation. Also, RX is different from TX, in that with RX we don't care about loss, only signal to noise. Ground loss is a contributor to those variations based on mounting height. N6RO, an old hand on topband with a great antenna farm, rearranges his M/6 station for topband contests to bring LOTS of his antennas to the station he uses single-op. That study is here. http://k9yc.com/AntennaPlanning.pdf 73, Jim K9YC On 3/15/2020 9:28 AM, sawye...@earthlink.net wrote: I put up a 160M full size inverted vee. Top at about 55ft and ends at around 15 feet. Just high enough to decouple some of the ground losses but other than that, straight up radiation for the most part. _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Topband: NVIS Antenna
I was reminded of my interest in re-installing a low 160M antenna to supplement by 2 el vertical phased array. And since there was no where to go this weekend and no College Hoops to watch, I thought, hey, I could get something up and play around with it in the Spring Stew. And that what I did. I put up a 160M full size inverted vee. Top at about 55ft and ends at around 15 feet. Just high enough to decouple some of the ground losses but other than that, straight up radiation for the most part. I compared that to my 2 element T top vertical phased array that is half wave spaced and fed in phase or 180 out of phase for an E/W or N/S pattern. At about 2 hours before sunset I started tuning around and listening to stations. Understand from my location in Vermont there is literally no one on within 100 miles of me almost all the time. Unless W1SJ or K2LE are on (SJ is 40 miles and LE is 80 miles). I was interested to hear that until about 30 mins before sunset - NONE of the signals we better on the NVIS inv vee - in fact virtually all were down by 5 - 15db. Then around that time I started to notice that the 200 mile out stations and as well the closer stations started being equal on the NVIS and a few louder by maybe 5dB. Then from Sunset for a good hour or more, MOST of the up to 200 mile out stations were 5 - 15dB louder on the NVIS inverted vee. Propagation is fascinating. It's a keeper to have in the arsenal for the selected need of 200 - 250 miles out from an hour before to maybe 1 - 2 hours after sunset on 160M. Comments welcome. 73 Ed N1UR _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
