Re: Topband: Non-resonant receive antennas
Hi Dick I never noticed any difference in receiving performance That's exactly what we should expect using a resonant dipole, it interact with any other antenna because the fiscal length is resonant, does matter if the feed impedance, if it is only a straight wire resonant it is like a director or director. Distance also is something hard to manage on 160m. 120ft is only 1/4 or .25 wave , heavely interact with other resonant elements. A low dipole is like an inverted V, used to be called unidirectional, a high dipole is different because the vertical field change intensity far from the ground, however the feed line is hardtop choke and remove the vertical common mode noise. Ladder line has huge advantage here , but not worth the effort . The low dipole and inverted V is unidirectional only if you disregard the polarization, using EZENEC it is easy to demonstrate that, check Plot Type: 3D plot and select Desc Options Ver.Horiz.Total. When you plot the 2D Azimuth Slice or Elev Slice, the vertical field is the red line and the horizontal a green line. The inverted V or low dipole is horizontal only at broadside with a 8 patter and some RDF, along the wire the Inverted V and low dipole is vertical polarized. Bothe fields are high angle, it means low gain at low angles. Both antennas work like a very short beverage along the wire and does not perform at all. Broadside there is a huge deep null on vertical signals, as a result the manmade noise is also attenuated that direction, the horizontal signal sky wave 20 to 40 degree has less attenuation, that situation there is an increase in the signal to noise ratio. The lobe is very wide and the SNR is better at the center and at 45 degree each side the vertical field is the same as the horizontal field, that's why these antennas are unidirectional, with the two fields the same there is no improvement on SNR after 45 degree from the center The situation where these antennas outperform vertical arrays is because they receive horizontal sky wave signals or high angles vertical or horizontal signals. Any receiver antenna without directivity is works like the attenuator in your radio, just reduce the overall gain decrease the Noise figure of the RX system but increase the IP3 reducing intermodulation. Almost the same thing as reduce the RF gain and increase the audio gain does. Receiver antennas to perform must have good RDF, and keep no other resonant anything around, only one resonant wire will be part of the RX system and change the patter, is the wire works like a director or reflector it would increase the RDF , the odds are not that and most of the cases the interaction makes the RX antenna patter useless. This long answer is to validate your observation, resonant dipoles does not provide any difference in receiver performance than your vertical or TX antenna. 73's JC N4IS -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Richard Karlquist Sent: Saturday, December 20, 2014 4:49 PM To: topband@contesting.com Subject: Re: Topband: Non-resonant receive antennas On 2014-12-20 13:06, Richard Jaeger wrote: I guess I should try a low dipole and see what happens. Dick, K4IQJ .. When talking about a low dipole, the question comes up as to why it must be low to work. Actually we don't know that it must be low to work. Very few of us are in a position to put up a high dipole, so the question is basically moot. However, in an attempt to gauge the influence of height, I A/B'ed two full size dipoles at 30 and 60 foot heights over a period of 6 months. The one not in use was floating to avoid interaction with the active one. I never noticed any difference in receiving performance. What seems to happen is that the signals are a few dB higher on the 60 foot wire, but the noise is commensurately higher. 30 feet was chosen for the minimum so that the wires didn't look like beverages (and because I have a bunch of 30 foot lengths of pipe). Rick N6RK _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Non-resonant receive antennas
When talking about a low dipole, the question comes up as to why it must be low to work. Actually we don't know that it must be low to work. Very few of us are in a position to put up a high dipole, so the question is basically moot. However, in an attempt to gauge the influence of height, I A/B'ed two full size dipoles at 30 and 60 foot heights over a period of 6 months. The one not in use was floating to avoid interaction with the active one. I never noticed any difference in receiving performance. What seems to happen is that the signals are a few dB higher on the 60 foot wire, but the noise is commensurately higher. Low is always in wavelengths, feet are too general. :) Your results are expected, because anything below 1/8th wave has little difference in pattern (except for loss of efficiency at low heights). On receive, only the pattern (and polarization) matters until you get into system internal noise floor limitations. The idea a really low dipole is quieter or has better high angle signal is a big problem with NVIS antennas and emergency services. People park 80 meter dipoles at a few feet and they are no quieter except for loss of efficiency (and in some poor installation cases less feedline radiation at low height). I had dipoles at ~300, maybe around 130-150, and 60 feet on 160, as well as non-resonant low dipoles. Once below ~150 ft, they all pretty much work the same except for gain reduction with reduced height. That gain reduction can be somewhat mitigated with a ground screen of some type, until the antenna gets too close to the screen. During the rare times the any dipoles were working very well, they all pretty much worked. The high dipole was closer to the vertical than the low dipoles at other times. Of course inside a few hundred miles was different. The high dipole, like the verticals, were dogs. Any dipole below ~150 ft was pretty much the same in close on sky wave. _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Non-resonant receive antennas
On 12/21/2014 7:58 AM, JC wrote: This long answer is to validate your observation, resonant dipoles does not provide any difference in receiver performance than your vertical or TX antenna. I didn't say that. I said that there was no difference between a dipole at 30 feet and a dipole at 60 feet. There is often a big improvement in receive on my low dipole vs a vertical, and not just at sun rise. Rick N6RK _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Non-resonant receive antennas
This is almost the way it worked here just at sunrise, both transmitting and receiving, except after sunrise the vertical hung in longest here. The brief and unpredictable window of horizontal superiority at this location is why I eventually just let the horizontal antennas all fall apart. The pattern was true for both high (~300 ft) and low (less than 150 ft) dipoles. We would get beat all the time in 160 pileups using a high dipole in contests on the second station, so much that I just took that antenna out of the selections. At this location, when the horizontal was good the verticals were still workable. So the horizontals never really extended anything, they just were better. The exception was during solar storms, where sometimes the verticals were poor compared to the horizontals for extended periods. 73 Tom If the band was open before my local sunrise (not always the case!), the verticals would always outperform the dipole by a large amount. However, as soon as we hit sunrise, the dipole would suddenly start equaling and then outperforming the verticals. The transition would take place in a matter of a few short minutes. Past sunrise, DX signals would drop into the noise on the verticals but would continue to hang in on the dipole. The dipole would sometimes extend the opening for me by 5 to 15 minutes, allowing me to make some contacts (mainly JA and VK, if the band was open in those directions) that would not have been possible with the vertical array. Sometimes the DX would be virtually inaudible on the verticals but Q5, although not strong, on the dipole. What is rather interesting, however, is that in the winter seasons of 2012-2013 and 2013-2014, this dipole advantage became non-existent. The dipole was never even close to the verticals, either before or after sunrise. It caused me to go outside a number of times to see if the dipole had fallen down, but that was never the case. Evidently the propagation mechanisms at work around sunrise have changed from a few years ago, at least at my QTH. So far in the 2014-2015 season, the dipole has still not provided any receiving advantage around sunrise. I generally don't operate much around local sunset, but I have never seen any dipole advantage at sunset. 73, John W1FV _ Topband Reflector Archives - http://www.contesting.com/_topband - No virus found in this message. Checked by AVG - www.avg.com Version: 2014.0.4794 / Virus Database: 4235/8762 - Release Date: 12/18/14 _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Non-resonant receive antennas
John, My experience mirrors your comments. In the mornings to JA and VK on 160M, the signals are usually best on my end-fire loop arrays, but around SR there is often a rapid shift to my inverted L transmitting antenna. The signals may or may not hold up on the loops. I guess I should try a low dipole and see what happens. Dick, K4IQJ .. On Dec 19, 2014, at 1:43 AM, John Kaufmann wrote: A few years ago, I put up a low, non-resonant dipole, about 150 feet long and 10 feet high for use as an auxiliary receiving antenna on 160. My main receiving antenna was and still is an array of short verticals. What I found at my W1 location after I installed the dipole is similar to what N5IA described at XZ0A. If the band was open before my local sunrise (not always the case!), the verticals would always outperform the dipole by a large amount. However, as soon as we hit sunrise, the dipole would suddenly start equaling and then outperforming the verticals. The transition would take place in a matter of a few short minutes. Past sunrise, DX signals would drop into the noise on the verticals but would continue to hang in on the dipole. The dipole would sometimes extend the opening for me by 5 to 15 minutes, allowing me to make some contacts (mainly JA and VK, if the band was open in those directions) that would not have been possible with the vertical array. Sometimes the DX would be virtually inaudible on the verticals but Q5, although not strong, on the dipole. What is rather interesting, however, is that in the winter seasons of 2012-2013 and 2013-2014, this dipole advantage became non-existent. The dipole was never even close to the verticals, either before or after sunrise. It caused me to go outside a number of times to see if the dipole had fallen down, but that was never the case. Evidently the propagation mechanisms at work around sunrise have changed from a few years ago, at least at my QTH. So far in the 2014-2015 season, the dipole has still not provided any receiving advantage around sunrise. I generally don't operate much around local sunset, but I have never seen any dipole advantage at sunset. 73, John W1FV _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Non-resonant receive antennas
On 2014-12-20 13:06, Richard Jaeger wrote: I guess I should try a low dipole and see what happens. Dick, K4IQJ .. When talking about a low dipole, the question comes up as to why it must be low to work. Actually we don't know that it must be low to work. Very few of us are in a position to put up a high dipole, so the question is basically moot. However, in an attempt to gauge the influence of height, I A/B'ed two full size dipoles at 30 and 60 foot heights over a period of 6 months. The one not in use was floating to avoid interaction with the active one. I never noticed any difference in receiving performance. What seems to happen is that the signals are a few dB higher on the 60 foot wire, but the noise is commensurately higher. 30 feet was chosen for the minimum so that the wires didn't look like beverages (and because I have a bunch of 30 foot lengths of pipe). Rick N6RK _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Non-resonant receive antennas
Hi John What is the orientation of you low dipole? I assume similar to XZ0A it is broadside N-S. In 2010 the SSW SSE propagation that I am calling TELP started with solid copy for 2 weeks in October of XU7ACY around 11:15z and at 2 weeks per month until March. 2011 was even better and Dec 29 and 30th were the best days I ever experienced LP. January 2012 this propagation just stopped from the best day to zero. Nada!!! During 2013 and 2014 LP on 160m was very rare. 2014 we had some good days with HS0 and DU7 per month., not even close to what happened 2010 , 2011. Also very few days opening near SS. I think your observation is the same as my , the dipole advantage became non-existent 2013 - 2014 because there was no propagation SSE SSW or TELP. I used to monitor a BC on 3915 from 9V1 to check for SSE SSW propagation but the station went QRT last March and I don't have another signal to check propagation from South Asia anymore so we depend on activity to know is the band is open and activity has been very low. I hope the SSW SSE propagation mode will be back next season, or maybe it will start like it stopped with a huge opening. Regards JCarlos N4IS -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of John Kaufmann Sent: Thursday, December 18, 2014 8:43 PM To: 'Top Band Contesting' Subject: Re: Topband: Non-resonant receive antennas A few years ago, I put up a low, non-resonant dipole, about 150 feet long and 10 feet high for use as an auxiliary receiving antenna on 160. My main receiving antenna was and still is an array of short verticals. What I found at my W1 location after I installed the dipole is similar to what N5IA described at XZ0A. If the band was open before my local sunrise (not always the case!), the verticals would always outperform the dipole by a large amount. However, as soon as we hit sunrise, the dipole would suddenly start equaling and then outperforming the verticals. The transition would take place in a matter of a few short minutes. Past sunrise, DX signals would drop into the noise on the verticals but would continue to hang in on the dipole. The dipole would sometimes extend the opening for me by 5 to 15 minutes, allowing me to make some contacts (mainly JA and VK, if the band was open in those directions) that would not have been possible with the vertical array. Sometimes the DX would be virtually inaudible on the verticals but Q5, although not strong, on the dipole. What is rather interesting, however, is that in the winter seasons of 2012-2013 and 2013-2014, this dipole advantage became non-existent. The dipole was never even close to the verticals, either before or after sunrise. It caused me to go outside a number of times to see if the dipole had fallen down, but that was never the case. Evidently the propagation mechanisms at work around sunrise have changed from a few years ago, at least at my QTH. So far in the 2014-2015 season, the dipole has still not provided any receiving advantage around sunrise. I generally don't operate much around local sunset, but I have never seen any dipole advantage at sunset. 73, John W1FV _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Non-resonant receive antennas
On a 120' x 120' electrically noisy city lot in SE NM I am considering, for receiving, attempting to maximize S/N ratio on DX signals by a method I have not seen discussed. As far as I can tell, the noise, while quite strong, is not coming from any discrete source/sources. My ear, which certainly can be fooled, tells me a signal from an antenna on the ground (if it is strong enough to be heard without a preamp) has a higher S/N ratio than on any of my present antennas (2 short 10' x 20' Ewes, a 12' diameter untuned loop, and a 100' foot endfed wire about 2' off the ground next to a fence). Would putting two antennas on the ground, using a preamp on each, fed to a phasing unit, offer any possibility of an improvement over what I now have? My transmitting antenna, a semi-inverted L, is detuned by a relay opening the connection between the antenna and the coax. Any information would be greatly appreciated. Paul W5DM _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Non-resonant receive antennas
My low dipole is broadside NE-SW but at only 10 feet high, it is essentially omnidirectional in azimuth and a cloud-warmer in elevation. The instances where I've seen the dipole provide a receiving advantage have all been short path, either into JA or VK/ZL after my sunrise. The sunrise skew path to the southwest, which occurs only rarely, is always best on the vertical array. I did work DU7ET on that path during March and April of last spring. That path seems to be best in high sunspot years. The sunset skew path to Asia has been non-existent here for the last few years and is best in low sunspot years. Back in 2006-2007, 9M2AX would come through on this path, but I have not heard Ross for two or three years now. I also miss the Singapore BBC station that was on 3915 kHz for many, many years. There is still the JA BC station on 3925 and North Korea on 2850. 73, John W1FV -Original Message- From: JC [mailto:n...@comcast.net] Sent: Friday, December 19, 2014 5:15 PM To: 'John Kaufmann'; 'Top Band Contesting' Subject: RE: Topband: Non-resonant receive antennas Hi John What is the orientation of you low dipole? I assume similar to XZ0A it is broadside N-S. In 2010 the SSW SSE propagation that I am calling TELP started with solid copy for 2 weeks in October of XU7ACY around 11:15z and at 2 weeks per month until March. 2011 was even better and Dec 29 and 30th were the best days I ever experienced LP. January 2012 this propagation just stopped from the best day to zero. Nada!!! During 2013 and 2014 LP on 160m was very rare. 2014 we had some good days with HS0 and DU7 per month., not even close to what happened 2010 , 2011. Also very few days opening near SS. I think your observation is the same as my , the dipole advantage became non-existent 2013 - 2014 because there was no propagation SSE SSW or TELP. I used to monitor a BC on 3915 from 9V1 to check for SSE SSW propagation but the station went QRT last March and I don't have another signal to check propagation from South Asia anymore so we depend on activity to know is the band is open and activity has been very low. I hope the SSW SSE propagation mode will be back next season, or maybe it will start like it stopped with a huge opening. Regards JCarlos N4IS _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: Non-resonant receive antennas
I noticed JC's comment below about a low dipole as a receiving antenna. Did I interpret that correctly? I've read of a Dipole on the ground as a low noise receive antenna for 160 but.can a non resonant dipole installed at low heights be better, as a receive antenna, than a vertical or L antenna? How about a non-resonant dipole, say, two feet above ground, at a length of 100 feet? Would you feed it with coax or figure out the Zo at 160 and use a suitably wound xfmr to match to 50 ohms??? Just athinkin' of ways to use available low horizontal space, albeit the available space is insufficient for a beverage. Thoughts??? 72, Jim Rodenkirch K9JWV From: n...@comcast.net To: jkaufm...@alum.mit.edu; topband@contesting.com Date: Wed, 17 Dec 2014 23:11:10 -0500 Subject: Re: Topband: 8 circle: DXE vs Hi-Z Hi guys Polarization does play a lot on 160m for two reasons. I can say that because I am using my HWF (two horizontal flags end fire) since 2009. The first one is local man made noise that propagate only vertical due the attenuation on the horizontal component near the ground. And Second the DX signal always come in both polarization. The result form the two reasons is an optimized signal to noise ration using horizontal polarization. I have both WF with the same RDF, during SR or SS there is almost no sky noise coming from the back because of the darkness, however local man made noise comes from any direction, especially if you live in a city lot like I do. Most of the time the noise is coming at the same direction you want to hear the DX, and if you add power line noise the situation deteriorates a lot for the VWF due vertical polarization. Using my HWF I normally get 10 dB better SNR than my VWF that has the same RDF and same aperture of 74 degree measures, I can turn the antenna and measure it, they are not optimized for best F/B, I optimized them for maximum rejection of local man made noise. The HWF is not a dipole. The two phased loops take of angle us 40 degree and there is a huge attenuation for signals above 60 degree. Low dipole is a huge issue if the dipole is resonant, it will interact with all other receiver antennas and will destroy directivity of all of them, if you want to use a low dipole make it not resonant. Gain in not important so it can be short as a 30 m dipole and still will hear the same way. Another issue with low dipoles is the amount of energy absorbed from the TX antenna. If you connect a power meter and a 50 ohms load o the low dipole and transmit KW on the TX antenna, you can measure several WATTS at the low dipole . You can burn you front end with a low resonant dipole. Adding to all that there is another very interesting observation from my last 5 year using a high RDF horizontal RX antenna, when the TX signal refract on the ionosphere the signal split in two waves, that was very well explained by K9LA. What I observed is that these two waves does propagate in different directions. I normally receive VK6 near my SR with better SNR horizontal from 210 degree SSW and with better SNR from 280 degree vertical. Sometimes the horizontal peak is 20 minutes before the vertical peak that is most of the time at my SR. 73's N4IS JC -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of John Kaufmann Sent: Wednesday, December 17, 2014 8:59 PM To: topband@contesting.com Subject: Re: Topband: 8 circle: DXE vs Hi-Z Good points about polarization. If the signals and/or noise are polarized predominantly in one state, then RDF may not be a good predictor of SNR performance, particularly if the antenna receives predominantly in an orthogonal polarization. On the other hand, if the polarization state of the signals and noise evolve randomly with no preference for any one state, which is often assumed for skywave signals, then RDF will be--on average--a good receiving metric, subject to the previous stated qualifications about the spatial distribution of the received noise. However, some of the past discussions on this reflector about preferential polarization of skywave signals on 160 may call into question the assumption of randomly polarized signals. 73, John W1FV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Richard (Rick) Karlquist Sent: Wednesday, December 17, 2014 3:19 PM To: Lee K7TJR; 'Terry Posey'; 'John Kaufmann'; topband@contesting.com Subject: Re: Topband: 8 circle: DXE vs Hi-Z All this discussion about RDF overlooks the issue of polarization. If you make an array of verticals with a certain RDF (assuming noise comes from all directions uniformly), the array will be better than an individual vertical by the RDF factor. However, what I have found is that a horizontally polarized antenna, such as a low dipole frequently receives considerably better than a
Re: Topband: Non-resonant receive antennas
Jim, If the arrival angle of the signals is high, then definitely the low dipole will perform stupendously. At XZ0A in 2000 we were having trouble the first few evenings receiving signals at our sunset and for a couple of hours afterwards. The Beverage RX antennas were working very effectively after that time period, for the entire night time. Our conclusion was that the signals were arriving not only skewed (what signals we were hearing were best on the VK/ZL Beverage and not the direct path on the JA/NA Beverage) but also high arrival angle. I installed a full sized dipole at 20' AGL, suspended by bamboo poles at the center (centered on the helicopter landing zone as we suspected the Myanmar Generals were not going to come visit us) and terminated in the jungle on either side of the helo landing spot. The dipole was oriented east/west, broadside to the N/S. Immediately at the start of that day's Topband operation the NA signals came right up out of the noise floor shortly before sunset. Q5 copy signals on the dipole were barely discernable while listening on the VK/ZL Beverage. For 3 weeks we enjoyed this RX signal capability during the early evening time period. BUT, when it was time for the signal path to change it did so within a 5 minute period every night. It was like someone was disconnecting one antenna and connecting the other, so dramatic was the switch of RX path from skewed, high arrival angle to direct path, much lower arrival angle over a period of a few short minutes. It was like clock work each evening. The low dipole RX antenna allowed an XZ0A 160 M contact to be entered in hundreds of NA log books which most likely would have never happened without it. My personal experience with low (10' AGL), full sized (1/4 WL) horizontal loops at my home station is they work very well for high arrival angle signals but are nearly deaf to low angle signals. Good luck, and YMMV. The low dipole is a specialty RX antenna. And you can never have too many RX antennas. If anyone would like to see photos of the low dipole at XZ0A, send me a direct request. 73 de Milt, N5IA -Original Message- From: James Rodenkirch Sent: Thursday, December 18, 2014 7:26 AM To: Top Band Contesting Subject: Topband: Non-resonant receive antennas I noticed JC's comment below about a low dipole as a receiving antenna. Did I interpret that correctly? I've read of a Dipole on the ground as a low noise receive antenna for 160 but.can a non resonant dipole installed at low heights be better, as a receive antenna, than a vertical or L antenna? How about a non-resonant dipole, say, two feet above ground, at a length of 100 feet? Would you feed it with coax or figure out the Zo at 160 and use a suitably wound xfmr to match to 50 ohms??? Just athinkin' of ways to use available low horizontal space, albeit the available space is insufficient for a beverage. Thoughts??? 72, Jim Rodenkirch K9JWV From: n...@comcast.net To: jkaufm...@alum.mit.edu; topband@contesting.com Date: Wed, 17 Dec 2014 23:11:10 -0500 Subject: Re: Topband: 8 circle: DXE vs Hi-Z Hi guys Polarization does play a lot on 160m for two reasons. I can say that because I am using my HWF (two horizontal flags end fire) since 2009. The first one is local man made noise that propagate only vertical due the attenuation on the horizontal component near the ground. And Second the DX signal always come in both polarization. The result form the two reasons is an optimized signal to noise ration using horizontal polarization. I have both WF with the same RDF, during SR or SS there is almost no sky noise coming from the back because of the darkness, however local man made noise comes from any direction, especially if you live in a city lot like I do. Most of the time the noise is coming at the same direction you want to hear the DX, and if you add power line noise the situation deteriorates a lot for the VWF due vertical polarization. Using my HWF I normally get 10 dB better SNR than my VWF that has the same RDF and same aperture of 74 degree measures, I can turn the antenna and measure it, they are not optimized for best F/B, I optimized them for maximum rejection of local man made noise. The HWF is not a dipole. The two phased loops take of angle us 40 degree and there is a huge attenuation for signals above 60 degree. Low dipole is a huge issue if the dipole is resonant, it will interact with all other receiver antennas and will destroy directivity of all of them, if you want to use a low dipole make it not resonant. Gain in not important so it can be short as a 30 m dipole and still will hear the same way. Another issue with low dipoles is the amount of energy absorbed from the TX antenna. If you connect a power meter and a 50 ohms load o the low dipole and transmit KW on the TX antenna, you can measure several WATTS at the low dipole . You can burn you front end
Re: Topband: Non-resonant receive antennas
Milt, Thanks to share with us your experience during XZ0A. When I started playing with the HWF I was surprised to hear XU7ACY almost every day between 11:10z and 11:20z SSW, during 2010 and 2011 , that happened 50% of the day from October to April. This kind of propagation I called it TELP, Trans Equatorial Long Path. The signals arrive from 40 degree elevation mostly horizontal polarized 20 minutes before SR SSW and 20 minutes after SS SSE. With the HWF I was able to work south Asia almost in a daily base when my colleges nearby only could hear them few day with vertical polarized antennas. The reason why I do believe this propagation is around the equatorial line is due the observation for this kind of propagation from the south hemisphere. Analyzing several long path QSO's from PY's on 160m, there is a common point , in all QSO's the signal was arriving near SS or SR coming from NNW or NNE. In both cases, from north hemisphere or south hemisphere the signal is really coming from the equatorial zone. K9LA demonstrated with a ray trace analyze that the signal refract almost 120 degree at 40 degree angle, you can check that on K9LA web page. I think what I experienced with XU, DU and even JA long path SSW is the same propagation mechanism you mentioned during XZ0A. Very few DX-expeditions uses that propagation mode and do not install any RX antenna to receive SSW and/or SSE. The XU7ACY extravagance QSO's was due the fact Perter was active every day and he installed a SSE /NNW reversible beverage. DU7ET was using a high inverted V broadside N/S that receives horizontal SSE. It is hard d to work DU from Florida until Robert installed that antenna, we worked him Jan, Feb, Mar, Apr, and June this year on 160m, we just missed him during May and I don't know why. By the way Robert worked WAS on 160 with that antenna from DU7ET. 73's N4IS JC -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Milt -- N5IA Sent: Thursday, December 18, 2014 9:56 AM To: James Rodenkirch; Top Band Contesting Subject: Re: Topband: Non-resonant receive antennas Jim, If the arrival angle of the signals is high, then definitely the low dipole will perform stupendously. At XZ0A in 2000 we were having trouble the first few evenings receiving signals at our sunset and for a couple of hours afterwards. The Beverage RX antennas were working very effectively after that time period, for the entire night time. Our conclusion was that the signals were arriving not only skewed (what signals we were hearing were best on the VK/ZL Beverage and not the direct path on the JA/NA Beverage) but also high arrival angle. I installed a full sized dipole at 20' AGL, suspended by bamboo poles at the center (centered on the helicopter landing zone as we suspected the Myanmar Generals were not going to come visit us) and terminated in the jungle on either side of the helo landing spot. The dipole was oriented east/west, broadside to the N/S. Immediately at the start of that day's Topband operation the NA signals came right up out of the noise floor shortly before sunset. Q5 copy signals on the dipole were barely discernable while listening on the VK/ZL Beverage. For 3 weeks we enjoyed this RX signal capability during the early evening time period. BUT, when it was time for the signal path to change it did so within a 5 minute period every night. It was like someone was disconnecting one antenna and connecting the other, so dramatic was the switch of RX path from skewed, high arrival angle to direct path, much lower arrival angle over a period of a few short minutes. It was like clock work each evening. The low dipole RX antenna allowed an XZ0A 160 M contact to be entered in hundreds of NA log books which most likely would have never happened without it. My personal experience with low (10' AGL), full sized (1/4 WL) horizontal loops at my home station is they work very well for high arrival angle signals but are nearly deaf to low angle signals. Good luck, and YMMV. The low dipole is a specialty RX antenna. And you can never have too many RX antennas. If anyone would like to see photos of the low dipole at XZ0A, send me a direct request. 73 de Milt, N5IA -Original Message- From: James Rodenkirch Sent: Thursday, December 18, 2014 7:26 AM To: Top Band Contesting Subject: Topband: Non-resonant receive antennas I noticed JC's comment below about a low dipole as a receiving antenna. Did I interpret that correctly? I've read of a Dipole on the ground as a low noise receive antenna for 160 but.can a non resonant dipole installed at low heights be better, as a receive antenna, than a vertical or L antenna? How about a non-resonant dipole, say, two feet above ground, at a length of 100 feet? Would you feed it with coax or figure out the Zo at 160 and use a suitably wound xfmr to match to 50 ohms??? Just athinkin' of ways to use available low horizontal space, albeit
Re: Topband: Non-resonant receive antennas
Not wanting to distract from this thread too much, but I'd like to ask a question of the group. If one had the opportunity to install two receiving antennas (such as loops EWE's etc.) for Topband in either a series or parallel configuration, which would be preferred. Since Rick correctly stated that RDF doesn't account for all variables, such as polarization, the same may be said for a pair of antennas in the above configurations. Two receive antennas in parallel will narrow the lobe, but two in series will bring down the upper lobes. Can anyone comment on the advantage or disadvantage of either configuration in real-world practice? Thanks, Jim - KR9U _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Non-resonant receive antennas
Since Rick correctly stated that RDF doesn't account Jim RDF is everything ! The RX antenna system is the only way to improve signal to noise ratio. All electronic device is not perfect and introduce noise and deteriorate the signal to noise ratio, including your radio too RDF is one way to measure directivity . You may do not need directivity to improve signal to noise ratio if you are operating from a very quiet location or a desert island on the pacific without man made noise. If you deal with noise at your location you will select the antenna with better directivity. That's adds another component how to cover all directions. Better RDF equals to better signal to noise ratio. That's is true for all bands, try to work 20 meter contest with a vertical with 1 kW and compare with a 5 elements Yagi with 100W. Your TX signal will be the same however for sure you will prefer to receive on the Yagi due its directivity. You won't hear much on the vertical Regards JC N4IS _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Non-resonant receive antennas
Thanks JC, I agree that the RDF number is significant when evaluating a receive antenna. I agree that no one antenna system will work all of the time. Consider we have two scenarios: One RX antenna system that consists of two parallel antennas (Broadside) , and the other is the same antenna configured in-line, toward the desired signal (Delayed series fed). What I am asking is if anyone has any, on-the-air experience and would recommend one antenna system over the other for *most conditions*. In other words, will an antenna that has a less lower elevation pattern generally outperform an antenna that has a narrower beam width, but a higher elevation angle? I think in this we need to consider the arrival angle of atmospheric noise in a broadside array vs. atmospheric noise in a series fed array.Since atmospheric noise propagates and the arrival angle will change, which scenario would provide the general overall better performance? Jim - KR9U _ Jim RDF is everything ! The RX antenna system is the only way to improve signal to noise ratio. All electronic device is not perfect and introduce noise and deteriorate the signal to noise ratio, including your radio too RDF is one way to measure directivity . You may do not need directivity to improve signal to noise ratio if you are operating from a very quiet location or a desert island on the pacific without man made noise. If you deal with noise at your location you will select the antenna with better directivity. That's adds another component how to cover all directions. Better RDF equals to better signal to noise ratio. That's is true for all bands, try to work 20 meter contest with a vertical with 1 kW and compare with a 5 elements Yagi with 100W. Your TX signal will be the same however for sure you will prefer to receive on the Yagi due its directivity. You won't hear much on the vertical Regards JC N4IS _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Non-resonant receive antennas
Since Rick correctly stated that RDF doesn't account Jim RDF is everything ! The RX antenna system is the only way to improve signal to noise ratio. All electronic device is not perfect and introduce noise and deteriorate the signal to noise ratio, including your radio too RDF is one way to measure directivity . I'm a little tied up with other things like paying work, but I see this is still going on. RDF is directivity, I just called it that to not confuse it with gain that is important to transmitting. I suggested it as a factor in deciding if an antenna is **likely** to be an improvement or not because: 1.) Front gain to rear wide area ratio, based on the null width of the entire rearward pattern, was being used. This method was rarely effective, unless noise largely existed only in the entire rear hemisphere. It is very unlikely to have grossly dominant noise exactly fit a rear hemisphere, and it is impossible to have that condition in more than one direction. 2.) People were using gain as a measure, specifically with closely spaced non-staggered Beverage antennas. If two Beverages are paralleled so close as to not change pattern one bit and not change S/N ratio one bit, gain increases 3 dB! Gain is a useless parameter until the receive system internal noise affects S/N ratio. There certainly are other things that are important, and I weigh more than raw RDF into my selections. (Someday when I have time I may publically document things.) Removing signal from directions where there is no noise or where there is very little noise can make things seem better by RDF when they are really not better, as can RFD improvements by reducing side or back response to levels below where noise or QRM detracts from copy. My preference with large area (not tall height) vertical arrays and Beverage arrays is a very clean pattern with deep nulls elevated above the horizon and maximum overall area removed from the pattern, but I always want to be sure the next direction selected does something useful before I lose too much from the presently selected array. What I have and use is the result of almost 40 years of reading and experimenting, but it only came together here because I have the room I always needed. Most of my life I lived on small lots, and what I did then was ideal. All antennas are compromises, and RDF might be the best (far above gain or other methods) going at the moment, but distribution of noise and QRM has to factor in by looking at the pattern. 73 Tom _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Non-resonant receive antennas
Judging from my own observations and feedback that I get I would say that using a low dipole or horizontal polarity antenna would also depend on what Latitude/Longitude your station is located and how close you are to the sea. Here above 45 degrees Latitude and 200 miles from the sea, I seldom see signals arriving that would benefit from a low horizontal antenna. It does happen however and always early in the a.m.. When FT5XO was on the air I saw their signal change from a very low angle signal received well with verticals to a high angle signal where none of my vertical receiving antennas exhibited any directivity in a couple hours one morning. I have only seen this in the morning when listening West into the Pacific. I have not heard it listening to the East in the evening. So, I say ask around in your area to see what the guys are happy with. I don't think you would hear as many DX signals in my location with a low horizontal as you would with verticals. I am pushing 200 countries on 160 having only used vertical receiving arrays. Or put up both as one can never have enough low-band receiving antennas. Lee K7TJR OR -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Wolf Sent: Thursday, December 18, 2014 10:30 AM To: 'JC'; 'Top Band Contesting' Subject: Re: Topband: Non-resonant receive antennas Thanks JC, I agree that the RDF number is significant when evaluating a receive antenna. I agree that no one antenna system will work all of the time. Consider we have two scenarios: One RX antenna system that consists of two parallel antennas (Broadside) , and the other is the same antenna configured in-line, toward the desired signal (Delayed series fed). What I am asking is if anyone has any, on-the-air experience and would recommend one antenna system over the other for *most conditions*. In other words, will an antenna that has a less lower elevation pattern generally outperform an antenna that has a narrower beam width, but a higher elevation angle? I think in this we need to consider the arrival angle of atmospheric noise in a broadside array vs. atmospheric noise in a series fed array.Since atmospheric noise propagates and the arrival angle will change, which scenario would provide the general overall better performance? Jim - KR9U _ Jim RDF is everything ! The RX antenna system is the only way to improve signal to noise ratio. All electronic device is not perfect and introduce noise and deteriorate the signal to noise ratio, including your radio too _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Non-resonant receive antennas
Jim What I am asking is if anyone has any, on-the-air experience and would recommend one antenna system over the other for *most conditions*. In other words, will an antenna that has a less lower elevation pattern generally outperform an antenna that has a narrower beam width, but a higher elevation angle? I understand your question now. Yes I have exactly that, a low elevation narrow bean VWF, that works best at 20 degree or lower and a same narrow bean but high elevation angle HWF best at 40 degree. I keep a record of new countries worked with one or another. The high elevation angle outperform the low elevation angle 95% of the time, in special near SS or SR. But the low elevation angle was the only antenna that can hear South Asia direct path due north. 9M2AX , BU2AQ, 4W6 over or near the North Pole. Let me say the same thing in another way. For DX signals coming due North 330 to 30 degree , the vertical low angle outperform the high angle always. It is based on the direction the signal is coming from and the interaction with the dip magnetic field. Like 9M4SLL on Mar 13th 2013 was strong 340 degree only heard with VWF, on Mar 17th the signal was coming SSE and the high angle was better, but copy with both antennas. 95% is a big number however the 5% could be a new country. Like 706T in the first and second night only copy on the vertical low angle, after they move to a new location the high angle RX antenna was better. They are complementary to each other, hard to pick one. 73's JC N4IS -Original Message- From: James Wolf [mailto:jbw...@comcast.net] Sent: Thursday, December 18, 2014 1:30 PM To: 'JC'; 'Top Band Contesting' Subject: RE: Topband: Non-resonant receive antennas Thanks JC, I agree that the RDF number is significant when evaluating a receive antenna. I agree that no one antenna system will work all of the time. Consider we have two scenarios: One RX antenna system that consists of two parallel antennas (Broadside) , and the other is the same antenna configured in-line, toward the desired signal (Delayed series fed). What I am asking is if anyone has any, on-the-air experience and would recommend one antenna system over the other for *most conditions*. In other words, will an antenna that has a less lower elevation pattern generally outperform an antenna that has a narrower beam width, but a higher elevation angle? I think in this we need to consider the arrival angle of atmospheric noise in a broadside array vs. atmospheric noise in a series fed array.Since atmospheric noise propagates and the arrival angle will change, which scenario would provide the general overall better performance? Jim - KR9U _ Jim RDF is everything ! The RX antenna system is the only way to improve signal to noise ratio. All electronic device is not perfect and introduce noise and deteriorate the signal to noise ratio, including your radio too RDF is one way to measure directivity . You may do not need directivity to improve signal to noise ratio if you are operating from a very quiet location or a desert island on the pacific without man made noise. If you deal with noise at your location you will select the antenna with better directivity. That's adds another component how to cover all directions. Better RDF equals to better signal to noise ratio. That's is true for all bands, try to work 20 meter contest with a vertical with 1 kW and compare with a 5 elements Yagi with 100W. Your TX signal will be the same however for sure you will prefer to receive on the Yagi due its directivity. You won't hear much on the vertical Regards JC N4IS _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Non-resonant receive antennas
A few years ago, I put up a low, non-resonant dipole, about 150 feet long and 10 feet high for use as an auxiliary receiving antenna on 160. My main receiving antenna was and still is an array of short verticals. What I found at my W1 location after I installed the dipole is similar to what N5IA described at XZ0A. If the band was open before my local sunrise (not always the case!), the verticals would always outperform the dipole by a large amount. However, as soon as we hit sunrise, the dipole would suddenly start equaling and then outperforming the verticals. The transition would take place in a matter of a few short minutes. Past sunrise, DX signals would drop into the noise on the verticals but would continue to hang in on the dipole. The dipole would sometimes extend the opening for me by 5 to 15 minutes, allowing me to make some contacts (mainly JA and VK, if the band was open in those directions) that would not have been possible with the vertical array. Sometimes the DX would be virtually inaudible on the verticals but Q5, although not strong, on the dipole. What is rather interesting, however, is that in the winter seasons of 2012-2013 and 2013-2014, this dipole advantage became non-existent. The dipole was never even close to the verticals, either before or after sunrise. It caused me to go outside a number of times to see if the dipole had fallen down, but that was never the case. Evidently the propagation mechanisms at work around sunrise have changed from a few years ago, at least at my QTH. So far in the 2014-2015 season, the dipole has still not provided any receiving advantage around sunrise. I generally don't operate much around local sunset, but I have never seen any dipole advantage at sunset. 73, John W1FV _ Topband Reflector Archives - http://www.contesting.com/_topband
