Topband: 2013 Visalia Top Band Dinner
The 2013 Visalia Top Band Dinner will be held on April 19, 2013. There will be a buffet dinner, door prizes including a Hi-Z Antennas Hi-Z 4 level 2 (PLUS6 Amps) System and a special program: Les Kalmus, W2LK: "ZL9HR - The Auckland and Campbell Island 160m Challenge." Cost is $40 (USD) per person. For for further details and reservations please see: http://www.dxconvention.com/pages/dinners-topband.html 73 - Steve WB6RSE _ Topband Reflector
Re: Topband: New 160M high performance receiving antenna at W3LPL
Hi Lee, Since I have two excellent receiving antennas to compare with (a 900 foot Beverage and a full size 4-square), I'm satisfied that I'm getting the expected performance from my BSEF receiving array. Its excellent directivity extends well down into to AM broadcast band. As you noticed after writing your 0013Z email, I'm using three 75 ohm Magic-T combiners as suggested by W1MK. The four RG-6 coaxial transmission lines connected to the verticals are cut to precisely identical lengths, 1/2 wavelength at 1840 kHz. The only potential source of VSWR induced phase shift would be the RG-6 coaxial cable that provides part of the phase shift between the front and rear pairs of verticals (along with a W8JI phase inversion transformer), but I believe that line is also operating at (or close to) 1:1 VSWR. I will perform a few more VSWR measurements just to be certain that all of the RG-6 transmission lines are operating at (or close to) 1:1 VSWR as planned. Thanks for your helpful comments. 73 Frank W3LPL Original message >Date: Sun, 3 Feb 2013 00:13:48 -0800 >From: "Lee K7TJR" >Subject: Topband: New 160M high performance receiving antenna at W3LPL >To: > > First let Me say this passive 8 circle antenna is a great antenna. I am > sure > it is outstanding compared to most receiving systems. > However, It seems to me a moot point to be discussing the merits of > minutia > in terms of the pattern from this 8 circle antenna. If you model this > antenna with > all the transmission lines and transformers etc., you will find that the > pattern >changes dramatically form 1.8 to 1.9 MHZ. Yes, it is perfect at the design >center > frequency. And this is modeling without the effects of the ground radials > often > used in the system. They will only make the following problem worse. I do not > have the NEC 4 engine so I cannot evaluate the radial influence. >So someone correct me if I am wrong, but here is why this happens. It is > incorrect to expect the delay in a transmission line to be as calculated > unless > one or both ends of it are terminated in its characteristic impedance. Also > unless it is multiples of 1/4 wave which we do not have here.The delay line in > this design is 37.5 ohms and the two elements feeding it are 37.5 ohms, a > match only at the design frequency. If you look at the output side of the > delay > line it is driving the output 18.75 ohms output transformer and it is also > seeing > the other two elements paralleled (37.5 ohms) so the load on the line is 12.5 > ohms. The delay line is not terminated on the load end for sure. And not on > the > source end off the design frequency as the frequency of the array changes. The > output impedance of the elements change naturally with frequency, so unless > you are at the design frequency, source impedance will be off 37.5 ohms and > the delay will be incorrect in the delay line. The delay varies with frequency > bottom line. > A combiner with a little more complicated impedance matching would help > this problem. >Lee K7TJR >_ >Topband Reflector _ Topband Reflector
Topband: New 160M high performance receiving antenna at W3LPL
My original message was scrubbed sorry. It is important to use the combiners with this array as Frank has. The simpler 2 transformer design may have more of a tendency to have the pattern shift with frequency if that is important to you. YMMV Lee K7TJR _ Topband Reflector
Re: Topband: Subject:RE: New 160M high performance receiving antenna at W3LPL
Hi Carl, I and many others have been using Fair-rite 2873000202 binocular cores with excellent success for years now. http://www.newark.com/fair-rite/2873000202/ferrite-core-cylindrical/dp/02E8908 Using a VNA to measure loss through a pair of back-to-back connected 9:1 Beverage matching transformers shows much less than 1 dB loss through the pair with low VSWR (I don't recall where I stored the detailed measurements I made years ago). I'll repeat the loss and VSWR measurements through pair of back-to-back 9:1 transformers, they're trivial to build. http://www.w8ji.com/Beverages/BEVtrans.jpg My BSEF receiving array is strictly monoband, the umbrella verticals are tuned to resonance at 1840 kHz and the spacings are specific to 160 meters. Later this year I plan to build two fully steerable 8-circle BSEF receiving arrays, one for 160 and one for 80 meters. http://www.w5zn.org/files/Design%20Construction%20&%20Evaluation%20of%20the%208%20Circle%20Vertical%20Array%20for%20Low%20Band%20Receiving%20Rev%203A%2002-25-2011.pdf Unlike a passive BSEF receiving array, an array of short verticals with high impedance amplifiers at the base of each vertical provides the basis for an excellent multi-band receiving array. I don't plan to take that route, I have adequate space for monoband BSEF receiving arrays. http://www.hizantennas.com/4_8_pro_8_element_array.htm http://www.dxengineering.com/search/department/antennas/section/receive-antennas-and-arrays/part-type/hf-receive-vertical-antenna-array-packages/receive-array-type/eight-circle/product-line/dx-engineering-receive-eight-circle-array-electronics-packages?autoview=SKU High gain amplifiers at the feedpoints of the verticals can pose a problem in the harsh RF environment of a multi-operator multi-transmitter contest station, particularly in my case where we have excellent capabilities to simultaneously receive within a few kHz of the transmitter. 73 Frank W3LPL Original message >Date: Sun, 3 Feb 2013 09:22:54 -0500 >From: "ZR" >Subject: Re: Topband: Subject:RE: New 160M high performance receiving antenna >at W3LPL >To: > >http://www.newark.com/fair-rite/2873000202/ferrite-core-cylindrical/dp/02E8908 > > >73 Mix Frank? I thought 31 was the latest choice but for monoband it doesnt >matter. > >Any plans on doing a 160-40M design? > >Carl > > >- Original Message - >From: >To: >Cc: "Ron Spencer" >Sent: Saturday, February 02, 2013 3:38 PM >Subject: Topband: Subject:RE: New 160M high performance receiving antenna at >W3LPL > > >> Hi Ron, >> >> Construction of a phase inversion transformer is covered in detail on page >> 23 of the excellent paper published by W5ZN and N4HY: >> >> http://www.w5zn.org/files/Design%20Construction%20&%20Evaluation%20of%20the%208%20Circle%20Vertical%20Array%20for%20Low%20Band%20Receiving%20Rev%203A%2002-25-2011.pdf >> >> My phase inversion transformer uses the Fairite 2873000202 binocular core >> popularized by W8JI for use in Beverage matching and receiving crossfire >> transformers. >> >> http://www.newark.com/fair-rite/2873000202/ferrite-core-cylindrical/dp/02E8908 >> >> My transformer windings are made of twisted red and white 26 AWG insulated >> telephone wire or you could use Category 5 Ethernet cable or just about >> any other small diameter insulated wire. The twisted pair is passed three >> times through both holes in the binocular core (three times returning back >> to the starting point of winding). The red wire is grounded at one end of >> the twisted pair and the black wire is grounded at the opposite end of the >> twisted pair. The remaining wires are the input and output of the phase >> inversion transformer. It took me longer to type this explanation than >> to fabricate a transformer! >> >> I'll be happy to answer any further questions. >> >> 73 >> Frank >> W3LPL >> >> >> >> >> Original message >>>Date: Sat, 02 Feb 2013 12:02:24 -0800 >>>From: Ron Spencer >>>Subject: BSEF array >>>To: donov...@starpower.net >>> >>>Frank sounds intriguing. Can you supply details of the phase inverting >>>transformer? >>> >>>Thanks >>> >>>Ron >>>N4XD >> _ >> Topband Reflector >> >> >> - >> No virus found in this message. >> Checked by AVG - www.avg.com >> Version: 10.0.1430 / Virus Database: 2639/5576 - Release Date: 02/02/13 >> > _ Topband Reflector
Topband: Ft Monmouth white paper on tree antennas
I thought this would be interesting material here from 1972 US Army white paper. http://www.dtic.mil/dtic/tr/fulltext/u2/742230.pdf 73 Pete W2PM Sent from my iPad _ Topband Reflector
Re: Topband: New 160M high performance receiving antenna at W3LPL
Hi Joel, Other than the three Magic T's, what other specific mods have you made to your 8-circles? Adding a T50-2 toroidal inductor and a BNC connector at the 50 ohm tap makes a quick job of adjusting resonance to exactly 1840 kHz. Much more work is planned later this year, building switchable 8-circles for 160 and 80 meters. Using one inch rebar for the base makes that job a snap, especially in my case where I must completely remove the antenna from my borrowed field every year and reinstall it in October. The rebar can be easily removed with a sledge hammer. I discovered that I couldn't unzip my 16 AWG speaker wire when its cold, I was breaking wires! No problem at all unzipping it at room temperature. Tks for all of your help! 73 Frank W3LPL Original message >Date: Sun, 3 Feb 2013 06:29:18 -0600 >From: Joel Harrison >Subject: Re: Topband: New 160M high performance receiving antenna at W3LPL >To: donov...@starpower.net >Cc: topband@contesting.com > > Frank - Good stuff and very glad you made public your work on > the array. > It is good to see the array is working very well at W3LPL. I > continue to have excellent performance from both of my BSEF > arrays (160 & 80 meter versions). > Robye (W1MK) and I had several conversations following > publication of my work on BSEF's which resulted in use of > Magic Tee's and a few other feed point mods. > 73 Joel W5ZN > > On Fri, Feb 1, 2013 at 11:00 AM, > wrote: > > My new 160 meter Broad Side - End Fire (BSEF) receiving > array is now in use and performing extremely well, > significantly better than my 900 foot Beverages and full > size 4-square transmitting antenna. > > Like most of us who live in developed areas, my RFI > environment has significantly degraded with the lack of > effective RFI regulation in recent years. Plasma TVs, > ubiquitous poorly filtered switching power supplies and > increasly popular high efficiency motors are steadily > raising our noise floor. With this new antenna 160 meters > is delightfully quiet again at W3LPL! > > Thanks to W8JI, W5ZN, N4HY and W1MK for their efforts in > designing, optimizing and publishing the details of this > wonderful high performance receiving antenna. The BSEF > array is now connected to the 160 meter input to my CW > Skimmer, it now has significantly better sensitivity than > when it was connected to my 900 foot NE Beverage. > > The description and photos of my new BSEF array are here: > > http://pvrc.org/bsef/bsef.html > > 73 > Frank > W3LPL > _ > Topband Reflector > > -- > 73 Joel W5ZN > > www.w5zn.org _ Topband Reflector
Re: Topband: New 160M high performance receiving antenna at W3LPL
Hi Frank, I used a pair of 270 foot spaced broadside 580 foot Beverages for several years but the improvement was insignificant compared to a single 580 foot Beverage. I replaced them with single 900 foot Beverages which perform slightly better than the 580 foot Beverages. I have inadequate space for more widely spaced broadside Beverages. We sometimes see claims broadside spacings less than 1/2 wave result in useful S/N or directivity improvements. They do not. Gain goes up 3 dB (because the individual elements are so lossy), but pattern does not change any significant amount. When pattern does not remove unwanted signal areas significantly more, S/N cannot change significantly. We can't improve things by nulling unwanted stuff out of an area that already has very little response. My results with Beverages are similar to your results. The problem with 1/2 wave spacing is it tries to force a null where the individual elements already have a null. In order to improve weak signal performance, we have to force new nulls where significant response exists with the basic element. We can't make things significantly better by just adding a new null inside an existing null, because there is already nothing of consequence there to get rid of. Since a 1 wave long Beverage has deep side nulls, adding a second antenna at a spacing that forces new nulls in the area of existing nulls is a waste of materials. You've surely built and evaluated more BSEF and 8-circle receiving arrays than any of the rest of us. I'm very new to them and after just a few days of evaluation I'm delighted with the results of my new BSEF receiving array consisting of four 25 foot W8JI umbrella verticals spaced 300 feet x 130 feet. I still have my 900 foot Beverages, but so far the performance of my new BSEF receiving array is consistently superior. If you were to install a new BSEF receiving array using four W8JI inductive/resistive loaded 25 foot umbrella verticals (not an 8-circle array) what spacings and fixed phasing would you use based on your experience and evaluations? I can't really give a specific answer because the optimum phase depends on the element combination and what people are after. What is best at one place is probably not best somewhere else, and it is the combination that matters. The only certainty is 1/2 wave broadside and 180-s phase is almost never optimum for anything, including transmitting. For receiving, I would plan the phasing or spacing of directive cells so each complementary cell forced the largest possible area null where other cells had significant undesired response. 73 Tom _ Topband Reflector
Re: Topband: New 160M high performance receiving antenna at W3LPL
Frank - Good stuff and very glad you made public your work on the array. It is good to see the array is working very well at W3LPL. I continue to have excellent performance from both of my BSEF arrays (160 & 80 meter versions). Robye (W1MK) and I had several conversations following publication of my work on BSEF's which resulted in use of Magic Tee's and a few other feed point mods. 73 Joel W5ZN On Fri, Feb 1, 2013 at 11:00 AM, wrote: > My new 160 meter Broad Side - End Fire (BSEF) receiving array is now in > use and performing extremely well, significantly better than my 900 foot > Beverages and full size 4-square transmitting antenna. > > Like most of us who live in developed areas, my RFI environment has > significantly degraded with the lack of effective RFI regulation in recent > years. Plasma TVs, ubiquitous poorly filtered switching power supplies and > increasly popular high efficiency motors are steadily raising our noise > floor. With this new antenna 160 meters is delightfully quiet again at > W3LPL! > > Thanks to W8JI, W5ZN, N4HY and W1MK for their efforts in designing, > optimizing and publishing the details of this wonderful high performance > receiving antenna. The BSEF array is now connected to the 160 meter input > to my CW Skimmer, it now has significantly better sensitivity than when it > was connected to my 900 foot NE Beverage. > > The description and photos of my new BSEF array are here: > > http://pvrc.org/bsef/bsef.html > > 73 > Frank > W3LPL > _ > Topband Reflector > -- 73 Joel W5ZN www.w5zn.org _ Topband Reflector
Topband: New 160M high performance receiving antenna at W3LPL
Meant to say the delay error varies with frequency bottom line. Lee K7TJR >The delay varies with frequency bottom line. > A combiner with a little more complicated impedance matching would help >this problem. _ Topband Reflector
Topband: New 160M high performance receiving antenna at W3LPL
First let Me say this passive 8 circle antenna is a great antenna. I am sure it is outstanding compared to most receiving systems. However, It seems to me a moot point to be discussing the merits of minutia in terms of the pattern from this 8 circle antenna. If you model this antenna with all the transmission lines and transformers etc., you will find that the pattern changes dramatically form 1.8 to 1.9 MHZ. Yes, it is perfect at the design center frequency. And this is modeling without the effects of the ground radials often used in the system. They will only make the following problem worse. I do not have the NEC 4 engine so I cannot evaluate the radial influence. So someone correct me if I am wrong, but here is why this happens. It is incorrect to expect the delay in a transmission line to be as calculated unless one or both ends of it are terminated in its characteristic impedance. Also unless it is multiples of 1/4 wave which we do not have here.The delay line in this design is 37.5 ohms and the two elements feeding it are 37.5 ohms, a match only at the design frequency. If you look at the output side of the delay line it is driving the output 18.75 ohms output transformer and it is also seeing the other two elements paralleled (37.5 ohms) so the load on the line is 12.5 ohms. The delay line is not terminated on the load end for sure. And not on the source end off the design frequency as the frequency of the array changes. The output impedance of the elements change naturally with frequency, so unless you are at the design frequency, source impedance will be off 37.5 ohms and the delay will be incorrect in the delay line. The delay varies with frequency bottom line. A combiner with a little more complicated impedance matching would help this problem. Lee K7TJR _ Topband Reflector
Re: Topband: New 160M high performance receiving antenna at W3LPL
Hi Tom, You've surely built and evaluated more BSEF and 8-circle receiving arrays than any of the rest of us. I'm very new to them and after just a few days of evaluation I'm delighted with the results of my new BSEF receiving array consisting of four 25 foot W8JI umbrella verticals spaced 300 feet x 130 feet. I still have my 900 foot Beverages, but so far the performance of my new BSEF receiving array is consistently superior. I used a pair of 270 foot spaced broadside 580 foot Beverages for several years but the improvement was insignificant compared to a single 580 foot Beverage. I replaced them with single 900 foot Beverages which perform slightly better than the 580 foot Beverages. I have inadequate space for more widely spaced broadside Beverages. If you were to install a new BSEF receiving array using four W8JI inductive/resistive loaded 25 foot umbrella verticals (not an 8-circle array) what spacings and fixed phasing would you use based on your experience and evaluations? tks 73 Frank W3LPL Original message >Date: Sat, 2 Feb 2013 23:58:15 -0500 >From: "Tom W8JI" >Subject: Re: Topband: New 160M high performance receiving antenna at W3LPL >To: , >Cc: Don Johnson > >> In W8JI's very rural area minimum main lobe beamwidth is more valuable to >> him than minimum sidelobes. Tom's choice of 330 foot broadside spacing in >> a very rural area with little or no local RFI makes lots of sense. >> > >I actually use a little more than 330 ft now in that array, and considerably >more spacing in broadside Beverage arrays. > >Half-wave spacing forms two nulls at ground level, directly of the sides of >the array. You have ONE null on each side at ground level. Most people fail >to realize the side nulls at half wave spacing are at ground level only. It >is a less than perfectly deep null at wave angles above earth level. > >Wider spacing, compared to 1/2 wave spacing, forms a null cone. This >provides **two nulls** at ground level off each of the sides (now you double >the chances of groundwave noise being in a null). Even more important, the >side null forms a cone that reaches maximum elevation off the side. > >This means directly off the side of an array, WIDER spacing gives a deeper >null. This is contarary to what most people assume, because they look at the >null as a ground wave side problem. People tend to overlook the fact that >distant signals and noise come from angles higher than zero degrees >elevation. > >They also overlook the fact that a wider spacing provides four groundwave >nulls (two on each side), instead of just two nulls (one on each side) of >1/2 wave spacing. > >I can't think of a single case, besides a single groundwave noise source >directly off the side, where 1/2 wave spacing would be an advantage. > ><<< >If you look at end-fire cell patterns, you will find closer spacing gives >more directivity. It is easier to have a wider null area with somewhat >closer spacing.>>> > >Right. > > > >> End fire spacing has essentially no effect on beamwidth and sidelobe >> levels, so Tom's choice of 70 foot end-fire spacing makes little if any >> measurable difference compared to 130 foot end-fire spacing. Larger >> end-fire spacing (up to 1/4 wavelength) is somewhat more forgiving of >> phasing errors and mismatched signal levels and slightly more >> efficient.>>> > >Actually there is another very common myth or mistaken assumption about >phasing. We assume phase difference between elements should be 180-s where s >is electrical degrees spacing. We assume with quarter wave (90 degree) >spacing we want 180-90 = 90 degree phase difference, or with 45 degree >spacing we want 180-45 = 135 degree phasing. Once again, despite being in >countless articles and books, this is almost always NOT optimum. The only >case where it is optimum is where we want a single zero wave angle null >directly off the back. > >This is almost never the case, because as with 1/2 wave broadside spacing, >this forms only ONE null at zero elevation. By increasing phase delay we >split the back null into TWO nulls at zero angle, and have a null cone that >is elevated directly off the back about the same as the zero elevation nulls >are angled off the side. > >It's really pretty silly, when we think about it for a while, to design >skywave systems or noise rejection systems that have a single groundwave >null peak. What almost any case demands is a null covering the widest >possible area, and to absolutely be above zero elevation. This not only does >a better job of notching unwanted signals and noise from skywave, it also >doubles the null area on the ground for local noise. > >If I had multiple groundwave noise sources, I would not use 1/2 wave >broadside spacing. I would use wider spacing. >If I had skywave side signals to reject, I would not use 1/2 wave broadside >spacing. > >The only case I would use 1/2 wave spacing would be ground wave noi
