++++++++++++++++ Date: Thu, 05 Dec 2002 06:58:29 -0500 To: "Dave Sergeant" From: Charles Greene Subject: Re: [Elecraft] re:Dreaming...a challenge for the Elecraft team (or the joys of QRP) Cc: elecraft at mailman.qth.net Dave and All, -- snip -- Here's an interesting take. I am experimenting with an EH antenna. Among other things, it's noise floor is consistantly 8 to 10 dB lower than a good, low noise hertz antenna, giving a S/N ratio improvement of 8 to 10 dB or more. I can now hear dozens of signals on PSK31 that are well into the noise on a hertz antenna. If we all used an EH antenna, we all could reduce our power level 8 dB or so. Here's a web site for EH antennas, if you want to check it out. http://eh-antenna.com/amateur.htm >I do not add /QRP to my callsign as that is not >within the UK licencing conditions (although many do send it). My >signal may be weak in the pile ups, but judging what I do work it is >not a limitation. A good operator should also be looking for the >weaker signals, and when I do get through it gives me that extra bit >of satisfaction. > >It gave me a little thrill when I received a batch of QSLs from the >bureau yesterday. Among them was a SWL card - I normally do not pay >much attention to those, but that was from a VU listener who had >heard my QRP signals while working an OH0 station on 15m. Quite a >surprise to get that!! > >Yes, it is perhaps unfortunate that the K2 is now longer seen as a >QRP rig, but that doesn't mean that those of us who are now QRP only >operators should change. > >73s Dave G3YMC >K2 #2498 >160 DXCC countries in 8 months Good work! 73, Chas, W1CG K2 #462 +++++++++++++++ From: "Tony Wells" To: "Helmut Usbeck" , Subject: Re: [Elecraft] Low Power Transmitter Date: Sat, 22 Feb 2003 15:35:39 -0000 Hi Helmut, Go to http://www.eh-antenna.com for more info. There is a kit available. The patent is at: The yahoo mail list is at: Regards, Tony +++++++++++++++ Reply-To: From: "Ron D'Eau Claire" To: Date: Sat, 22 Feb 2003 17:10:34 -0800 Subject: [Elecraft] EH antenna?? > What's an EH antenna? > > Regards, > Helm. WB2ADT [K2, 2698] I don't pretend to be an antenna engineer so when I first heard about them I went looking for information. There's what claims to be a detailed description at http://www.eh-antenna.com/documents/EH_ANTENNA_DEFINITION.pdf I don't know if these are the originators, so I can't say if the is the definitive write up on the subject. I read I carefully and decided I was an ol' hound dawg chasing my tail. It divides antennas into two categories, Hertzian and EH. The "EH" of course is the "new concept". They forgot (or didn't know about) Marconi antennas, which were the first and still possibly the most common antenna in use for communications today. A Marconi, of course, is fundamentally a 1/4 wave radiator that uses an "earth image" to resonate. A Hertzian antenna is, fundamentally, a half wave radiator that operates independently of the earth. The Hertz is the oldest antenna, of course, being what Hertz himself used to demonstrate the propagation of electromagnetic waves. The problem is that Hertzian antennas become very big at low frequencies. Hertz used a half-wave loop at about 50 MHz for his experiments. Marconi invented the idea of using a 1/4 wave radiator working against ground because he needed, to get the range he wanted with the technology available to him, to work at wavelength in the hundreds of meters. Makes for a HUGE loop to carry around. Back to the EH, then. Reading the description, it claims to be a Hertz antenna with a special phase shift network added. This phase shift network exactly offsets the "j" factor in the input impedance to the antenna. That's good. But it's not new! It's what we ALL do when we adjust an antenna or the ATU. When we adjust an antenna (or our ATU clicks us to an SWR of 1:1) all we are doing is compensating for the inherent "j" factor (capacitive or inductive reactance) so the antenna will take power efficiently. If you don't recognize the term "j-factor" it's the complex or reactive part of any impedance. An impedance is written as R j(X) where "R" is the resistive part of the impedance and the "X" is the reactive part. For example, if an antenna is exactly 1/2 wave long and way up in the air (several wavelengths above ground) it will have an impedance at the center of about 75 j0 ohms at "resonance". That is, the impedance is purely resistive (75 ohms) and the reactance is zero, so it will take power from a 75 ohm generator (transmitter) very efficiently. IF the antenna is too long, it will show inductive reactance. If it happened to show 50 ohms of inductance, we would write the impedance as 75 j+50 ohms. (Note the plus sign. Inductive reactance is positive and capacitive reactance is negative.) The reactance causes the current and voltage to no longer be in phase. If they are no longer in phase, not as much power is being transferred. (Power is the product of the voltage and current. If the voltage peak and current peaks do not occur at the same instant, their product will be less than if they did). So the challenge is to get the voltage and current back in phase. We add 50 ohms of capacitive reactance to the circuit. We add 75 j+50, our antenna, to our ATU providing 0 j-50 and the sum is 75 j0 or a perfect "match". Our SWR meter is happy, our r-f gets out, and we are happy. That's what the EH antenna description says it does, so I quite certain that it works very well. The only thing is, I can't figure out what's new in all of that. I've been doing that for 50 years, and folks since Marconi had been doing that for over 50 years before I first loaded up a wire with r-f. Perhaps someone can enlighten all of us about what is different about an EH antenna that we don't all have. Ron AC7AC K2 # 1289 ++++++++++++++++++ Date: Sun, 23 Feb 2003 09:38:47 +0000 To: elecraft at mailman.qth.net From: Trevor Day Reply-To: Trev at secornwall.com Subject: Re: [Elecraft] EH antenna?? I took an interest in 'EH' antennas around a year ago and I am still not convinced either way. I will say however that there are aspects of the EH performance that I find it difficult to explain. In brief: With the exception of 6m, the antennas below are driven by my K2 at around 10 watts with a fixed length coax feeder of four feet. Each antenna stands on the window sill inside the shack directly in front of and slightly above the radio. The shack is in a spare room around 12 feet above ground in an urban environment.The 6m antenna has a transverter in circuit but otherwise the same conditions apply. The first antenna I built was the simple 20m version on a cardboard tube (This is the 'taster' antenna you can construct in 30 mins on the kitchen table). It is about a foot long or thereabouts and I did get it to resonate but the performance was fairly poor. A few CW QSOs into central Eu with reports around 449 were about the best I could manage. I only spent a day with this one and the band condx *could* have been poor. (I do not have any HF antennas at this location normally except for a random wire). The next was a simple version of the 40m antenna. This weighs in at around 4 inches in diameter and about 2 feet long. It performed reasonably well, with QSOs around the UK and into central Eu on CW and SSB. I was encouraged enough to build a second version, this time with the more complex matching arrangement. This worked as well as the first (direct comparisons were not possible, so any small improvement was likely to go unnoticed). I did manage to receive a 559 from a W2 before being flattened by QRM! The most significant thing about this antenna, and the factor that makes it so obviously different from an ATU loaded chunk of metal, is its bandwidth. Once tuned (I use an MFJ Analyser) its bandwidth on 40m between the 2:1 SWR points is in excess of 100 kHz. Try and achieve that with a commercial mobile whip, never mind less than 2 feet of metal tubing. If anyone can explain it within conventional antenna theory then I would be pleased to hear it. Out of interest, and largely as a novelty, I built a 6m version. It is 0.75 inch in diameter and around four inches long. It is wound onto polythene tubing with a BNC socket at the bottom to connect the 4 foot of feeder. It is too small to stand on its own, so it hangs by a few inches of nylon cord from the curtain rail. During last summers SpE openings and with 4 watts (the max my barefoot transverter will supply) it worked all over Eu mainly SSB with S9 plus reports in most cases. I managed one comparison with my outdoor 5 element yagi on a 'real' dx signal from the Caribbean; with the Yagi 559, with the 'EH' 529. Not bad when you consider the Yagi is 10 feet above my roof and the EH is indoors, 20 feet lower, and in a window facing East (the opposite direction)! My apologies for the lengthy response, but I see many postings about this antenna from people who have read the alleged theory and come to their own conclusions but have never tried it for themselves. I have to say, that I have difficulty with the explanations of how this antenna works, but I am more interested in results rather than the theory. I am sure that there is probably a set of circumstances that will explain all of the above results; but will someone please explain how this antenna achieves the bandwidth that it does without being a dummy load? (It doesn't get warm and it does radiate) Trev G3ZYY +++++++++++++++ Reply-To: From: "Ron D'Eau Claire" To: Subject: RE: [Elecraft] EH antenna?? Date: Sun, 23 Feb 2003 09:59:31 -0800 Sorry. I didn't mean to cause a dust-up about antennas on the Elecraft reflector. I simply tried to answer a question about something I have looked into and found more questions than answers myself, Hi! I CAN answer your question about the bandwidth, Trev. Again, it's straightforward antenna theory. All you need for adequate bandwidth are adequate losses. Now, in a truly big antenna, such as really long "long wire" or a loop many wavelengths around, most of the r-f gets radiated, so there is very little to be "reflected" back to the source. Such an antenna has the best kind of losses: radiation "losses". The signal all got launched! Unfortunately, that takes antennas many, many wavelengths long, so most of us live with our doublets and loops and other intermediate sized antennas and, by being careful, we get very good efficiencies out of them. Most of the r-f is consumed in the "radiation resistance" -- that fictional resistance that represents the r-f that got radiated. But, as an antenna gets smaller relative to the wavelength of the r-f signal, the reactance changes more quickly with frequency. Hence, the "bandwidth" over which radiation occurs efficiently will be narrow. Looking at it another way, the "bandwidth" over which the r-f voltage and current are in phase is very narrow, and unless they are in phase the antenna cannot take the r-f power. So "happiness" in a small antenna is a small bandwidth. It's a good sign that the antenna is working efficiently. Even so, it's easy to make a small antenna show a wide bandwidth. All you have to do is to increase the resistance. For example, if you put a 3 d-b attenuator in between the transmitter and any antenna (or even NO antenna), it will only absorb 1/2 of the transmitter's power and the SWR will never exceed 2:1. But that doesn't mean a thing in terms of radiation efficiency. B&W has for years sold a "wide band" doublet that works just that way for Ham and marine use. You give up half the transmitter power, but you don't have to worry about matching networks, ATU's etc. The B&W has the resistive element out in the center of a "folded dipole" configuration, so r-f flows through the antenna wires and much of it is radiated. It's a workable "compromise" antenna where bandwidth is more important than efficiency. Small antennas with big "loading" (or as the EH calls it "phase shift") networks frequently show very wide bandwidths when the network is lossy. And as the antenna gets smaller the matching network can be carrying hundreds of amperes of r-f, even at QRP power levels. Again, such an antenna may work halfway around the world on a milliwatt under the right conditions. The point is that you might be putting 5 watts into and getting microwatts out, and sometimes microwatts will travel a LONG distance. That's why I find that "on-the-air" tests that are not conducted under carefully controlled conditions with the proper instrumentation are virtually useless. Evaluating an antenna objectively requires setting up a situation where the performance can be carefully measured. I don't own the acres of land or the test equipment for an "antenna range", so I'm out of luck on that score. I am NOT suggesting that people who hook up a new antenna and work fantastic DX with it are lying, but I am saying that the "real world" is too variable to collect valid data about one antenna being better without carefully-controlled conditions where antennas can be compared. I'm as interested in "why" something works as I am in operating it, so that's a question I often ask. When I built my first crystal set many moons ago, the first question I had was "How does this thing work?". I haven't changed. Ron AC7AC K2 # 1289 ++++++++++++++++++ Date: Sun, 23 Feb 2003 21:52:42 -0500 To: elecraft at mailman.qth.net From: Charles Greene Subject: [Elecraft] My Experiences with EH antennas on 20 meters Ron and All, The EH antenna really works, well. It's efficiency, as an antenna, is on the order of 95%, as compared to about 75% for the full size 20 meter vertical with elevated radials I build last summer, and few percent for a short fat dipole the same size but just loaded with a loading coil because of the high losses in the loading coil. On 20 meters, its beam width is on the order of a few degrees, concentrated near the horizontal. As it needs no ground, its ground losses are very low. It doesn't need a return ground path that includes the lossy earth ground. One of my EH antennas for 20, (I have four) has a bandwidth of 200 kHz, and it achieves this without resistance or other tricks. On performance, the only way to fully evaluate an antenna is to do a one for one comparison with other antennas. I have done this, and it is better in some directions than my G5RV and vice versa, as the G5RV is directional on 20 meters. However, the EH antenna beats my relatively good Hustler 6BTV in gain consistently by 2 to 3 dB. It does this by improved efficiency but mainly by a narrower beam width concentrated at a low angle. On receive, it gives the most striking performance difference. I used spectrogram to measure the noise floor and the signal level of PSK31 signals on 20 meters. The noise floor is a full 10 dB lower than my Hustler 6BTV, and 13 dB lower than my G5RV. With a gain of 2 to 3 dB over the Hustler, the improvement in received signals is 12 to 13 dB. I was hearing signals on 20 I never knew were there with the other antennas. Let me repeat this so I am not misunderstood. The gain improvement of the EH antenna compared to the Hustler 6BTV is 12 to 13 dB only on receive signals and receive signals ONLY, and primarily because of a lower noise floor. To put things in perspective, it is a good vertical antenna. It is not a replacement for a good three element beam. It doesn't even beat a good full wave loop, or most of the other multi-element gain arrays. As far as I know, no one has used one in a gain array, but I don't know why this cannot be done. It has to be high, some say 1/4 wave length, but I an working on this with some tests I am running, as I have had good results at 3' high. On 40 meters and below, the narrow beam width is actually a detriment, so the antenna is made shorter so the vertical beam width is wider at the expense of the gain of a narrower vertical beam width. It is a single band antenna. On 80 and 160, it's bandwidth is very narrow unless you want to use very large diameter (8" and 16") elements, or remotely tune it. It needs to be clear of other antennas, and like any antenna, it performs best when clear of obstructions. I tried mine inside with poor results, but I may put my mailing tube version in my attic, as it can't stay outside during the rain. I am going to put one on a 10 ft pole on my sea wall in an out-of-the-main-view location where it should be a great performer for DX. I installed my vertical with elevated radials on my sea wall last summer, but it did not meet the approval of the landscape inspector (XYL). It seems to be a good antenna for portable use, as it is small on 40 through 6, and can easily be hoisted up a mast or on a string over the limb of a tree. It easily beats a shortened vertical, and it is easier to hoist than a full size dipole. It's good for the guy with a small back yard. I am going to try one for 160 next summer and mount it on my roof, as I don't have a 160 meter antenna or the room for an adequately performing one. I am running some tests now and working with one of the designers, so we can more fully understand some of the performance characteristics of the antenna. Others have had the same or better results. GL on yours. You can even buy an excellent kit at www.eh-antennas.com 73, Chas, W1CG K2 #462 +++++++++++++++++ Reply-To: "Thomas Kuehl" From: "Thomas Kuehl" To: Subject: Re: [Elecraft] My Experiences with EH antennas on 20 meters Date: Sun, 23 Feb 2003 21:37:29 -0700 Hello Charles, The E/H antenna has been a subject of controversy within the antenna community. Although antennas are my primary interest in amateur radio and I've published a few articles on them, I am not qualified to pass judgement regarding the E/H antenna's operation or performance. With that said, there are some learned and experienced hams whom have a good deal more experience and antenna knowledge than myself. The following links may prove helpful to anyone contemplating acquiring or building their own E/H antenna. Generally, it appears that the analysis of the E/H antenna, and the practical experiences with it, indicate that its gain is down somewhere around 10 to 20 dB from common reference antennas. Please see the following articles at: http://www.w8ji.com/e-h_antenna.htm http://www.qsl.net/iz7ath/web/02_brew/18_eh/index.htm I am truly surprised that you have achieved such high levels of performance with your E/H antenna. Best Regards, Thomas - AC7A (Tucson) +++++++++++++++++++ From: "Jerry Felts" To: Subject: Re: [Elecraft] My Experiences with EH antennas on 20 meters Date: Sun, 23 Feb 2003 22:09:52 -0700 Ya know, I've played with a couple of EH Antennas and they have both work great for me. Thats running qrp, and with it sitting on the shelf over my radio. I really don't care what other people say or think about them! I just know mine work just fine. +++++++++++++++++++ From: "Tony Wells" To: Cc: Subject: Re: [Elecraft] My Experiences with EH antennas on 20 meters Date: Mon, 24 Feb 2003 10:14:24 -0000 > Charles wrote: > > > The EH antenna really works, well. It's efficiency, as an antenna, is on > > the order of 95%, as compared to about 75% for the full size 20 meter Vic wrote: > How did you determine this? Do you know the radiation resistance? I suspect > the radiation resistance is very, very low...and as a result, so is the > efficiency. This debate reminds me *so* much of the mag loop debate of 15 years ago. The problem with all this this stuff is firstly that antennas are not an exact science, and probably never will be. Secondly the variable environment at an individual's QTH , is , well , variable. Like many others, I was not convinced about the effectiveness of mag loops until I saw a well-built design in action - a 80M SSB contact across the Atlantic on 50W. I've also seen some pretty poorly-built mag loops. Like many others I also will not be convinced until I see a well-built EH in action. I've scheduled my first EH build for end of this month. We'll see what happens :-) The plus points of the EH antenna, apart from being small, is that it is easy to build using houshold DIY parts, and cheap as a kit to buy for experimenting with. If you look at the patent application it also *might* be able to provide something that no small HF antenna can offer - a highly directional beam, using a dish. The difficulty with the EH antenna is that like mag loops in the early days, the guys that "invented" or "discovered" them are not good at communicating their designs. This is not meant as disrespect. It's just life. Also, the "ham" community is can slow at times in adopting new technologies ;-) Two things will facilitate the wider adoption of interest in EH Antennas. 1. A regularly high-scoring DX contester needs to team up with a EH antenna constructer and win some prizes using the antenna. Volunteers? 2. There needs to be clear and unambiguous wiring digrams and designs that can be reproduced without error. This means that the docs and kit instructions need to be produced by people that *do not* understand the antenna theory, and have them reveiwed by people that *do* undertsand. I've helped a tiny bit with this by entering into a "design dialog" on the EH mail list and producing a wiring diagram on the yahoo mail list resource. Similarly others have submitted their hand-drawn practical designs. This is all good. For more info on the subjects, here are the starting points to work from: The main website:,http://www.eh-antenna.com There is a kit available. The url for the patent is below. It will get groken up by your mail viewer, so it may be easier to go to the web site and type the pat. no. in manually. The patent no. 6486846 http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=/netahtm l/search-adv.htm&r=1&f=G&l=50&d=PTXT&p=1&p=1&S1=6486846&OS=6486846&RS=648684 6 The yahoo mail list is at: http://groups.yahoo.com/group/eh-antenna/ Regards, Tony M3CJF G7IGG ++++++++++++++++ Date: Mon, 24 Feb 2003 07:57:41 -0500 To: Vic Rosenthal From: Charles Greene Subject: Re: [Elecraft] My Experiences with EH antennas on 20 meters Cc: elecraft at mailman.qth.net Vic, Tnx for comments. The antenna has a high impedance; for purposes of the network calculation, an antenna load of 30 -j994 ohms is used which was empirically determined. This value is dependent on the capacitance between the elements which is on the order of 10 pF. It is matched to 50 ohms with a simple L network which also functions to produce the 90 degree phase shift. The elements in two of my antennas are 2" diameter copper tubes 7.5" long, and 1" Al or Cu tubes in the other two, so the loss in the elements is very low, and probably is dielectric in nature rather than ohmic. You can calculate the network for the phase shift and also the loss in it with the KM5KG network design program. The loss in the network is on the order of 3 to 5%. If you put the parameters of the antenna in the right part of the KM5KG program, you get 50 ohms at the input. I have measured the return loss of the antenna up to -45 dB using a return loss bridge, which corresponds to a SWR of less than 1.02:1 at resonance. To tune the antenna with a transmitter, I use ten watts and connect a OHR set up to read reverse power, finally on the 100 mw scale. Of course, this has nothing to do with the performance of the antenna, but just measures how an L network can easily match the antenna impedance to 50 ohms. Of course the antenna beam is reflected from ground or in my case, the sea water for the semi-circle starting at 180 degrees and working around to North for 5 miles or so until you hit land, but the radiation starts out like it is coming from a vertical beam about 10 wide without side lobes, and goes on from there. You can't model the antenna, but a normal 1/4 wave vertical antenna on my sea wall modelled with EZNEC using a sea water ground shows a narrow beam width at less than 10 degrees vertical angle in the far field. Using a medium ground at the other directions in EZNEC I would estimate is reasonable accurate as concerns the far field vertical beam pattern. I didn't mean to mislead you in this respect, I and probably was not exactly correct in my statements. The antenna just is relatively immune from ground losses in the near field as it doesn't use a ground return, but performs like a normal vertical for reflections and ground losses in the far field. The Hustler is a trap vertical and I have a radial field consisting of 24 radials of 480 feet #14 wire total. The radial field is not nearly enough on 40 and 80, but it is reasonably good, and the performance of the antenna is reasonably good on 20. I estimate it has above average performance for a vertical, and it also benefits from sea water reflection in the fresnel zone, as it is 50' from the salt water. It beats my G5RV on 20 but not on 40. I also compared The EH antenna with my G5RV, which is really an apples and oranges comparison as there are differences in directivity in both horizontal and vertical patterns between the vertical antenna and the horizontal antenna. The point is, I did not just compare the EH antenna with a poorly performing vertical antenna. I won't try to go into the theory of operation of the antenna, and if anyone wants to say these guys don't know what is going on precisely, you are correct. I just concentrate on performance and factually report my experiences. It appears use the same theory as the Cross Field Antenna, CFA, discussed in the Antennx on-line magazine, although the physical properties of the antennas are different. There is a lot of information at the US EH Antenna web site: www.eh-antennas.com Also of interest are some of the links found there. One additional link is: http://hem.bredband.net/sixens/EH_ANTENN_SM5DAJ.htm which has links to other European sites. The Europeans are ahead of US hams in a lot of respects concerning EH antennas, particularity those in Sweden and Italy. I guess I better get off the subject or Eric will throw me off the reflector. If I get flames, I need to address them, but I do not flame in return. Any questions, please ask off line. At 07:55 PM 2/23/2003 -0800, you wrote: >Charles Greene wrote: > > > The EH antenna really works, well. It's efficiency, as an antenna, is on > > the order of 95%, as compared to about 75% for the full size 20 meter > > vertical with elevated radials I build last summer, and few percent for a > > short fat dipole the same size but just loaded with a loading coil because > > of the high losses in the loading coil. -- snip -- >Vic K2VCO 73, Chas, W1CG K2 #462 ++++++++++++++++ Date: Mon, 24 Feb 2003 12:08:28 -0500 To: "Jerry Felts" , From: Ed Tanton Subject: Re: [Elecraft] My Experiences with EH antennas on 20 meters And that's fine Jerry. Playing around with things is one of ham radio's greatest assets. If you want to do it right, however, try performing an A-B comparison on the antenna using a switch, with anything else-preferably a simple dipole. We tried a commercially available E-H antenna at NOGaQRP-complete with the antenna company's people. The scenario: 20M (I think-might've been 15M); a Saturday morning; and 4 different antennas: 1) an E-H; 2) an very-small (~ 4 ft diameter) loop; 3) a PLP-Vertical; and 4) a full-sized dipole. I listened as I switched back and forth multiple times over a period of 20 minutes-until I was completely satisfied further switching was a waste of time. CONCLUSIONS: 1) There was never a single time the E-H exceeded any of the other antennas. Not even once. Including the Very Small Loop. 2) There was never a single time the E-H was the equal of any of the antennas-except the very small loop. 3) There was never a single time the dipole and the PLP-Vertical were not NOTICEABLY better than the E-H. Up until that morning, had a pretty open mind about such antennas. I thought that perhaps they might be at least minimally competitive. Absolutely, positively NOT. The antenna company's people were VERY nice to bring this unit for our tests-it isn't like I have some axe to grind. They made a very nice presentation about how it worked, and I derive no satisfaction whatsoever in relating this. If you simply cannot put up any other kind of antenna, it is certainly better than nothing. BUT... two old sayings were never more true than for this antenna test: 1) There ain't no such thing as a free lunch. 2) The bigger, the higher, the better. I would like to point out that these are my conclusions-not the club's. I am not implying the club may have a different conclusion(s)-just that these are my own. 73 Ed Tanton N4XY Ed Tanton N4XY 189 Pioneer Trail Marietta, GA 30068-3466 website: http://www.n4xy.com ++++++++++++++++++ From: Reed White Organization: Alta Research To: Elecraft at mailman.qth.net Subject: Re: [Elecraft] My Experiences with EH antennas on 20 meters Date: Mon, 24 Feb 2003 10:00:28 -0800 Thank you, regarding your experiences with the EH antenna. Very interesting. In my opinion, your presentation of the combination of physics and actual experience (somewhat controlled experiments) is a good use of reflector bandwidth. ... Reed K7FLY ++++++++++++++++++++ Date: Mon, 24 Feb 2003 13:35:22 -0800 From: Eric Swartz WA6HHQ - Elecraft Organization: Elecraft To: n2tk at arrl.net Cc: "'Reed White'" , Elecraft at mailman.qth.net Subject: Re: [Elecraft] My Experiences with EH antennas on 20 meters Hi, In general we encourage discussion of Elecraft products -and- a wide range of related areas on this reflector. Antennas are certainly an area that directly relate to the use of K1s and K2s. (Of course you can cross post to more than on e forum at once if appropriate.) If a topic gets out of control I will pop up and rein it in :^). Let's avoid a discussion of what should or should be on the reflector or if it should be split into different sub groups. In general we do not want to fragment this group. Please feel free to direct any comments on list content directly to me instead of using list bandwidth to discuss them. 73, Eric WA6HHQ Elecraft List Manage ++++++++++++++++ From: "Stuart Rohre" To: , Subject: Re: [Elecraft] EH antenna?? Date: Mon, 24 Feb 2003 17:20:21 -0600 HI, a wide bandwidth is usually a sign of an inefficient antenna, thus the dummy load is full bandwidth on most of the ham bands. The best way to get an idea of how an EH is working for you, is to erect a comparison dipole at modest height. The EH can work, but we have worked DX (hams have) from light bulbs sitting on a pole. See the Force 12 Antennas web site for an interesting write up on his phased light bulbs used for DXing. Small antennas can work, but the Physics must meet muster, and efficiency is where they usually fall short, and causes it to have wider bandwidth than a mobile whip for example. 73, Stuart K5KVH +++++++++++++++++ Reply-To: From: "George, W5YR" To: , "'Reed White'" , Subject: RE: [Elecraft] My Experiences with EH antennas on 20 meters Date: Mon, 24 Feb 2003 15:58:35 -0600 For what it is worth, the EH has been talked to death on the antenna newsgroup and reflector. 73/72, George Amateur Radio W5YR - the Yellow Rose of Texas +++++++++++++++++++ Reply-To: "Bob Lewis (AA4PB)" From: "Bob Lewis (AA4PB)" To: Subject: Re: [Elecraft] EH antenna?? Date: Mon, 24 Feb 2003 18:53:33 -0500 > a wide bandwidth is usually a sign of an inefficient antenna Not necessarily. Wide bandwidth can be obtained without reducing efficiency in several different ways, including using large element diameters. Bandwidth only reduces efficiency when it is the result of added IR losses. ++++++++++++++++++ Date: Mon, 24 Feb 2003 20:29:58 -0700 From: "James R. Duffey" To: W1CG at QSL.net, elecraft at mailman.qth.net Subject: [Elecraft] The 20 M E-H Antenna Chas - Thanks for sharing your experiences with the E-H antenna. There is nothing magic about the E-H antenna. It is an electrically short antenna fed in the center. One can calculate the radiation resistance and loss resistance of such an antenna without much trouble. From these it is simple to calculate the efficiency. The efficiency of the 20 M E-H antenna is about 5% to 10%. I posted such calculations on QRP-L a while back when someone suggested that the E-H antenna would perform comparably to an inverted vee. I can reproduce them if you wish. Ed Hare made some comparisions wiht a 40 M E-H and an inverted vee at W1AW and came to the same conclusion. So, I am curious as to how you calculated or measured the 95% efficiency number for the E-H antenna that you quote. A typical dipole is about 90% to 95% efficient. The radiation pattern for a small center fed antenna is very similar to that of a full size dipole, varying by only a few degrees. So I am also curious as to your comments on a narrower beam width concentrated at low angles. I do not see how this can be achieved with the E-H antenna geometry. It is cleat that you are happy with your E-H, but I think that most hams would be happier with a more conventional and somewhat larger antenna.- Dr. Megacycle K6MC/5 ______________________ James R. Duffey KK6MC/5 Cedar Crest NM 87009 DM65 ++++++++++++++++++ Date: Mon, 24 Feb 2003 19:30:01 -0800 From: "John, KI6WX" To: Elecraft Mailing List Subject: [Elecraft] EH Antenna Patent After reading all of the posts on the EH Antenna, I went to the patent office at www.uspto.gov and printed out Patent # 6,486,846 to see what is so special about this antenna. The patent makes the following claims. -An antenna radiating structure that has two coaxially mounted parts (such as a non-resonant dipole or a bicone) -A matching network so that the E and H fields are in phase (this is a complicated way of saying that the voltage and current are in phase, i.e. the antenna input is resistive, not reactive). I see nothing unique in the claims about the radiating structure of the antenna. The patent was probably issued due to the design of the matching network. The detailed description describes a dipole operating at 7 MHz. Each side of the dipole is a 12" long aluminum cylinder with a diameter of 4.5". The disclosure states that this antenna plus matching network had a bandwidth of 500 kHz. The radiation resistance of this dipole is pretty low, but the large diameter cylinders will also have a low electrical resistance due to the large diameter, so the radiation efficiency might be reasonable. I haven't tried to analyze the loss in the matching network, but these can be significant when matching to the low radiation resistance. The gain of this antenna will be the same as a short dipole, which is a few tenths of a dB less than a half-wave dipole. The real key to the performance is probably the loss in the matching network, which I think will be greater than the loss in the radiating elements of the antenna. If you had a lossless matching network, the performance of the antenna at a single frequency would be the same whether you used the patented matching network or any other matching network that provided a resistive match to the transmitter. The biggest advantage to the patent is that it allows the antenna to have a much broader bandwidth than a conventional short antenna. However, you can also get a broad bandwidth using an antenna tuner. If you ignore losses in the antenna and the matching network, this antenna will perform no better or worse than any other physically small antenna, and should have virtually identical performance to a half-wave dipole at the same height and polarization. The losses in the antenna and matching network could make the performance significantly worse than a resonant dipole. There is no way that this antenna could have more gain than a resonant dipole. -John KI6WX +++++++++++++++++++ From: "Tony Wells" To: "John, KI6WX" Cc: Subject: Re: [Elecraft] EH Antenna Patent Date: Tue, 25 Feb 2003 10:06:34 -0000 Hi John, I don't personally have any bias one way or other on the efficacy on the EH, as I've yet to build one myself. However being English, I have great sympathy for the "underdog", enjoy taking part in long queues in shops, and frequently wear corduroy pants, smoke a pipe and wear a deerstalker hat :-) But seriously. I don't think anyone has ever claimed EH has more gain than a regular dipole. I believe the claims I've seen in print, is that a good EH, mounted at the correct height *approaches* the gain of a well-erected dipole whilst having a very small size compared with a full-size dipole. This is a very important point, because how many people can erect a full size 80M or 160M dipole in their backyard? Even a full size EH antenna for 136KHz can be built by obsessives in larger backyards. Personally I think it is a waste of time to compare a 20M EH with a good 20M dipole. Moe importantly, lets compare a 160M EH with a compromise 160M dipole. That would be a more significant test. There are two other claims in the patent which I think are very important to test. Firstly on RX the antenna is supposed to be deaf to E-only radiation and H-only radiation. Therefore the ant is supposed to have good immunity to man-made electrical interference. Some testers have reported that fact. The second claim is that by use of some kind of "dish" behind the antenna, it will be possible to "focus", or at least sheild from directions other than the intended path, the outgoing and incoming radiation. Again the focussing/shielding of radiation in this way very problematic in most backyards, particularly on 40, 80 and 160M. The implications of this type of working are enourmous - including the possibility of EME HF transmission & reception. IMHO Tony M3CJF G7IGG ++++++++++++++++ Date: Tue, 25 Feb 2003 05:25:59 -0800 To: elecraft at mailman.qth.net From: Larry Weaver Subject: Re: [Elecraft] EH Antenna Patent At 02:06 AM 2/25/2003, Tony Wells wrote: >There are two other claims in the patent which I think are very important to >test. Firstly on RX the antenna is supposed to be deaf to E-only radiation >and H-only radiation. Therefore the ant is supposed to have good immunity to >man-made electrical interference. Some testers have reported that fact. Whether the E-only/H-only explanation is correct or not, the receive enhancement is certainly possible on bands limited by external noise. I use my tribander for receiving on 160 & 80 and sometimes on 40. The signal strength is much less but the signal-to-noise is often much better than on either a resonant dipole or vertical. 73...Larry N6TW ++++++++++++++++++ Reply-To: From: "Ron D'Eau Claire" To: Subject: RE: [Elecraft] EH Antenna Patent Date: Tue, 25 Feb 2003 07:46:41 -0800 For superb low noise on HF, don't overlook on-the-ground or even "underground" antennas as well. While they will be pretty 'punk' radiators (typically 16 db below a dipole at 50 feet up) they seem to have very LOW noise pickup and much better signal-to-noise ratios than most "in the air" antennas. The downside is very low signal levels from them - typically 16 dB or so just like when transmitting - but the K2 has the 20 dB preamp built in that should make up for that and the 160 meter module offers the alternate antenna input for a receive-only antenna. Ron AC7AC K2 # 1289 ++++++++++++++++++++ Date: Tue, 25 Feb 2003 19:30:24 -0800 From: "John, KI6WX" Subject: Re: [Elecraft] EH Antenna Patent To: Tony Wells Cc: elecraft at mailman.qth.net Tony > > But seriously. I don't think anyone has ever claimed EH has more gain than a > regular dipole. I believe the claims I've seen in print, is that a good EH, > mounted at the correct height *approaches* the gain of a well-erected dipole > whilst having a very small size compared with a full-size dipole. > > This is a very important point, because how many people can erect a full > size 80M or 160M dipole in their backyard? Even a full size EH antenna for > 136KHz can be built by obsessives in larger backyards. Personally I think it > is a waste of time to compare a 20M EH with a good 20M dipole. Moe > importantly, lets compare a 160M EH with a compromise 160M dipole. That > would be a more significant test. This really is an impedance matching issue. A wide impedance range antenna tuner can match a physically short antenna, or a non-resonant antenna. The E-H antenna patent describes a matching network to broadband match a physically short antenna, but you will be limited to one band. A KAT2 antenna tuner might do just as well with the same antenna, but you could use the antenna on many bands. The key to the gain relative to a full size dipole is the loss in the matching network and I see nothing in the patented matching network that would be lower loss than other possible matching networks. > > There are two other claims in the patent which I think are very important to > test. Firstly on RX the antenna is supposed to be deaf to E-only radiation > and H-only radiation. Therefore the ant is supposed to have good immunity to > man-made electrical interference. Some testers have reported that fact. For far field noise, the E and H field strength are always related by the impedance of space. For near field noise, the E and H fields may differ from this, but the power in these components always fall off faster than distance-squared, so they don't propagate very far. Polarization discrimination is important; most local noise is transmitted by power lines which preferrentially transmit a horizontal E-field; a vertical E-field antenna will respond less to this noise. Finally, your transmission line and its connection into your radio can also have a large effect on noise sensitivity; the mismatch at the antenna can effect this sensitivity. > > The second claim is that by use of some kind of "dish" behind the antenna, > it will be possible to "focus", or at least sheild from directions other > than the intended path, the outgoing and incoming radiation. Again the > focussing/shielding of radiation in this way very problematic in most > backyards, particularly on 40, 80 and 160M. The implications of this type of > working are enourmous - including the possibility of EME HF transmission & > reception. > This won't work because of diffraction. The reflector would have to be a significant fraction of a wavelength to have any effect. You would be better off using several of these compact antennas in a phased array to provide gain in a specific direction. Just because a patent makes a claim, doesn't mean it will actually work. My favorite patent illustrating this principle is 6,025,810 "Hyper-light-speed Antenna". This is for an antenna that transmits a signal faster than the speed of light. -John KI6WX ++++++++++++++++++ Reply-To: From: "George, W5YR" To: , Subject: RE: [Elecraft] EH Antenna Patent Date: Wed, 26 Feb 2003 11:43:23 -0600 Thanks for filling in the blanks, Earl. Glad to see that the Socratic approach still works. And just to fill in the blanks a bit more, the presence of both fields in quadrature space relationship and in-phase time relationship and with a magnitude ratio of 377 (ohms) constitutes radiation in the far field. The cross-product of the two fields defines the Poynting vector which describes the direction of the radiating wave as well as its magnitude. Near-field conditions can be considerably different. There can be regions of predominately E-field or H-field concentration but this does not constitute "radiation" in the sense of far-field phenomena. Interesting stuff . . . amazing that four little equations could say so much. 73/72, George Amateur Radio W5YR - the Yellow Rose of Texas Fairview, TX 30 mi NE of Dallas in Collin county EM13QE "In the 57th year and it just keeps getting better!" -----Original Message----- From: elecraft-admin at mailman.qth.net [mailto:elecraft-admin at mailman.qth.net]On Behalf Of k6se at juno.com Sent: Wednesday, February 26, 2003 10:32 AM To: w5yr at att.net; elecraft at mailman.qth.net Subject: RE: [Elecraft] EH Antenna Patent George, W5YR wrote: "What is "E-only" or "H-only" radiation?" ========== The ARRL Antenna Book says: "Although the solid pattern of an antenna cannot be shown adequately on a flat sheet of paper, cross-sectional or plane diagrams are very useful. Two such diagrams, one in the plane containing the axis of the antenna and one in the plane perpendicular to the axis, can give a great deal of information. The former is called the E-plane pattern and the latter the H-plane pattern. These designations are used because they represent the planes in which the electric (symbol E), and the magnetic (symbol H) lines of force lie, respectively." ========== All electromegnetic waves have both E-plane and H-plane components and, as George pointed out, "You can't have one without the other". 73, de Earl, K6SE ++++++++++++++++++ Date: Thu, 27 Feb 2003 19:47:48 -0800 From: "John, KI6WX" To: Elecraft Mailing List Subject: [Elecraft] E-H Antenna Simulation in NEC Just for fun, I ran the E-H Antenna described in the patent 6,486,846 in NEC-4.1. I used the antenna and matching network described in Figure 1. The antenna consists of two aluminum cylinders that are 12" long and 4.5" in diameter. The operating frequency is 7 MHz. I assumed that the Q of the parts in the matching network were 1000. The calculations were done with the antenna in free space. The input impedance of the antenna is 0.036-j2114 ohms. This is a very low radiation resistance with lots of reactance that needs to be removed in the matching network. The efficiency of the radiating elements in the antenna is 98.9%. This is expected since the radiating elements have a large diameter. The very low resistance and high reactance are a real challenge in the matching network. The simulations show that the matching network will dissipate most of the power. Less than 1% of the power will get through the matching network to the antenna. Finally, the matching network does not force balanced currents to flow through both terminals of the transmission line. This means that the transmission line will radiate. I would expect that most of the radiation will occur from the transmission line if it is longer than a few feet. If it is longer than a 1/4 wavelength, the overall efficiency of the antenna and transmission line could be pretty good even though the antenna is radiating less than 1% of the power. -John KI6WX ++++++++++++++++++++