|
Antenna recommendation needed
Hi all,
I've had a planning application for a tower turned down which is a real pain. My options are now very limited. I'm in a bungalow with a roof apex height of 18 feet and I'm not allowed to put up anything much above this roof line it transpires, so inverted vees that need to be mounted high up at the feed point like G5RVs are not possible for me. My garden boundaries limit the length of any wire antenna I might wish to put up to about 120 feet overall. On the plus side, though, the QTH is several hundred feet ASL close to the top of the hill and am not overshadowed by any trees or buildings to speak of. What's my best choice for an HF antenna under these circs? (I mostly do CW on 20m & 40m, but would like a bit more band choice ideally if poss). Many thanks. Many thanks. |
Antenna recommendation needed
Bruno wrote:
Hi all, I've had a planning application for a tower turned down which is a real pain. My options are now very limited. I'm in a bungalow with a roof apex height of 18 feet and I'm not allowed to put up anything much above this roof line it transpires, so inverted vees that need to be mounted high up at the feed point like G5RVs are not possible for me. My garden boundaries limit the length of any wire antenna I might wish to put up to about 120 feet overall. On the plus side, though, the QTH is several hundred feet ASL close to the top of the hill and am not overshadowed by any trees or buildings to speak of. What's my best choice for an HF antenna under these circs? (I mostly do CW on 20m & 40m, but would like a bit more band choice ideally if poss). Many thanks. Many thanks. Verticals; if you have a lot of area, phased vertical arrays. -- Jim Pennino |
Antenna recommendation needed
On Sun, 18 Jan 2015 21:28:07 +0000, jimp wrote:
Verticals; if you have a lot of area, phased vertical arrays. Aren't verticals more inclined to generate interference? BTW, my plot is 120' by 90' so I think an array at HF will be impossible. The feed point will be pretty much central to the plot, though. |
Antenna recommendation needed
"Bruno" wrote in message ... Hi all, I've had a planning application for a tower turned down which is a real pain. My options are now very limited. I'm in a bungalow with a roof apex height of 18 feet and I'm not allowed to put up anything much above this roof line it transpires, so inverted vees that need to be mounted high up at the feed point like G5RVs are not possible for me. My garden boundaries limit the length of any wire antenna I might wish to put up to about 120 feet overall. On the plus side, though, the QTH is several hundred feet ASL close to the top of the hill and am not overshadowed by any trees or buildings to speak of. What's my best choice for an HF antenna under these circs? (I mostly do CW on 20m & 40m, but would like a bit more band choice ideally if poss). Many thanks. You may want to put up an off center fed antenna. Good for most all bands except 15 meters. Whatever, stick up something and get on the air. While it might not be the best, anything to get on the air with to start and later you can refine the antenna system for what you have. If you do put up a vertical, most of them will need to have radials burried just under the ground. The main thing is not to overthink things to start with. Start simple, get on the air and if it doesn't work well, put something else up when you have time. There was something in QST magazine a few months ago. They were vertical loops. I tried them for the 18 and 24 mhz band, but they did not work nearly as well as my OCF and dipoles cut for those bands. I have a coax switch so I could switch the antenas in just a fraction of a second. However the other antennas are at 50 feet high on the ends and the loop was only about 5 feet off the ground at the bottom. |
Antenna recommendation needed
Bruno wrote:
Hi all, I've had a planning application for a tower turned down which is a real pain. My options are now very limited. I'm in a bungalow with a roof apex height of 18 feet and I'm not allowed to put up anything much above this roof line it transpires, so inverted vees that need to be mounted high up at the feed point like G5RVs are not possible for me. My garden boundaries limit the length of any wire antenna I might wish to put up to about 120 feet overall. On the plus side, though, the QTH is several hundred feet ASL close to the top of the hill and am not overshadowed by any trees or buildings to speak of. What's my best choice for an HF antenna under these circs? (I mostly do CW on 20m & 40m, but would like a bit more band choice ideally if poss). Many thanks. Many thanks. I think Ralph Mowery is right -- get on the air with almost anything you canfind including just a hunk of wire, and while you are having the fun of operating you can decide on something that meets your desires. Radiating comes first -- the rest later! Irv VE6BP RADIATE OR DIE TRYING! |
Antenna recommendation needed
Bruno wrote:
On Sun, 18 Jan 2015 21:28:07 +0000, jimp wrote: Verticals; if you have a lot of area, phased vertical arrays. Aren't verticals more inclined to generate interference? No. BTW, my plot is 120' by 90' so I think an array at HF will be impossible. The feed point will be pretty much central to the plot, though. A 40M four square would be a push, but a 20M a slam dunk. DXEngineering has a lot of stuff and info for building various vertical arrays with phased feeding. The simplest array is 3 verticals about .23 lambda tall spaced at about ..34 lambda with just the center one fed. With the other two undrounded, you get a typical, omnidirectional vertical pattern. If you ground the outer two (think remote relays) you get a broadside pattern like a dipole with about 3.5 dBi gain. Of course your ground will make a difference and likely the more radials you can bury the better it will be unless you live in a swamp. Verticals want a good ground, horizontals want a better than .5 lambda height. -- Jim Pennino |
Antenna recommendation needed
Ralph Mowery wrote:
snip There was something in QST magazine a few months ago. They were vertical loops. I tried them for the 18 and 24 mhz band, but they did not work nearly as well as my OCF and dipoles cut for those bands. I have a coax switch so I could switch the antenas in just a fraction of a second. However the other antennas are at 50 feet high on the ends and the loop was only about 5 feet off the ground at the bottom. In my adventures of modeling loops close to ground, I've found them lacking except in the case of the hentenna; They work very well as close as one foot to the ground. A 17M hentanna is going to be a bit tall though. -- Jim Pennino |
Antenna recommendation needed
On Sunday, January 18, 2015 at 4:08:31 PM UTC-6, Bruno wrote:
On Sun, 18 Jan 2015 21:28:07 +0000, jimp wrote: Verticals; if you have a lot of area, phased vertical arrays. Aren't verticals more inclined to generate interference? BTW, my plot is 120' by 90' so I think an array at HF will be impossible. The feed point will be pretty much central to the plot, though. I would probably string up parallel coax fed dipoles and have them at the low height. IE: 18-20 feet off the ground if that's all you can do. They will still work fairly well overall. Say if you can stick a short 1-2 ft stub mast on the roof, run dipoles from it, and feed with a single coax for both bands. Run the legs out to wherever you can tie them off. IE: trees, or short masts in the back yard/garden, etc. Won't be a gang buster DX setup, but plenty good enough for general use. With 40 and 20 dipoles, you would also have 15 meters, running the 40 legs. And you can feed more dipoles from the same coax if you want more bands. Using the coax as a feed line, no tuner required and low system losses. And also no need to worry about laying out radials. |
Antenna recommendation needed
"Bruno" wrote in message ... Hi all, I've had a planning application for a tower turned down which is a real pain. My options are now very limited. I'm in a bungalow with a roof apex height of 18 feet and I'm not allowed to put up anything much above this roof line it transpires, so inverted vees that need to be mounted high up at the feed point like G5RVs are not possible for me. My garden boundaries limit the length of any wire antenna I might wish to put up to about 120 feet overall. On the plus side, though, the QTH is several hundred feet ASL close to the top of the hill and am not overshadowed by any trees or buildings to speak of. What's my best choice for an HF antenna under these circs? (I mostly do CW on 20m & 40m, but would like a bit more band choice ideally if poss). Many thanks. Many thanks. For many years, my antenna space has been restricted or limited. I favor verticals in those circumstances. I used a ground mounted Butternut for many years and it was OK. The grounding system was five heavy insulated wires, each five feet long and terminated in 6 foot ground rods. The idea for that grounding configuration came from a study by E-Systems done in the 1970s. Currently I use a 16 foot vertical mounted on a rather large metal patio cover. I feed it with 20 feet of coax and do the ATU inside the shack. I'm currently thinking about adding a remotely controlled ATU at the base of the antenna. For mobile use I have an Outbacker, and I have tried it on the metal patio cover. It works, but is marginal. If you get stuck with a mobile sized antenna, I'd recommend a bugcatcher. If you can handle a 30 foot vertical (advertised by MFJ and others) it might work well with a good ground. If the real estate is limited for ground wires, just do the best you can, and live with it. If your restrictions do not allow a permanent 30 foot vertical, you might get permission to tilt it down when not in use. Good luck! Wayne W5GIE |
Antenna recommendation needed
|
Antenna recommendation needed
"Wayne" wrote in message ... If you can handle a 30 foot vertical (advertised by MFJ and others) it might work well with a good ground. If the real estate is limited for ground wires, just do the best you can, and live with it. If your restrictions do not allow a permanent 30 foot vertical, you might get permission to tilt it down when not in use. I have worked a few stations on 20 M that are using a vertical about 43 feet tall. I think that will exceed the heigth that can be installed at that location, but if not, something to think about. If the band is in good shape, it is possiable to work with minimal antennas. I have worked many mobile stations with the screwdriver antennas on 20 meters and they had very good signals. |
Antenna recommendation needed
"Ralph Mowery" wrote in message ... "Wayne" wrote in message ... If you can handle a 30 foot vertical (advertised by MFJ and others) it might work well with a good ground. If the real estate is limited for ground wires, just do the best you can, and live with it. If your restrictions do not allow a permanent 30 foot vertical, you might get permission to tilt it down when not in use. # I have worked a few stations on 20 M that are using a vertical about 43 feet # tall. I think that will exceed the heigth that can be installed at that # location, but if not, something to think about. # If the band is in good shape, it is possiable to work with minimal antennas. # I have worked many mobile stations with the screwdriver antennas on 20 # meters and they had very good signals. Yes. I meant 43 feet. That was either a typo or a 75 year old brain fart. |
Antenna recommendation needed
Ralph Mowery wrote:
"Wayne" wrote in message ... If you can handle a 30 foot vertical (advertised by MFJ and others) it might work well with a good ground. If the real estate is limited for ground wires, just do the best you can, and live with it. If your restrictions do not allow a permanent 30 foot vertical, you might get permission to tilt it down when not in use. I have worked a few stations on 20 M that are using a vertical about 43 feet tall. I think that will exceed the heigth that can be installed at that location, but if not, something to think about. If the band is in good shape, it is possiable to work with minimal antennas. I have worked many mobile stations with the screwdriver antennas on 20 meters and they had very good signals. Hustler 4BTV 20 feet, 40, 20, 15, 10 $159 5BTV 23 feet, 80, 40, 20, 15, 10 $189 6BTV 24 feet, 80, 40, 30, 20, 15, 10 $209 DXEnginerring Tilt Base mounting system: $61 to $106 depending on frills. How much for a tower, installation, and antennas? A 43 foot vertical with an ATU at the base will run 160 to 10 meters. There is no city in the US that regulates pounding a piece of pipe in the ground and putting a BTV series antenna on top of it in your back yard. Well, I probably shouldn't say "no" given the flakyness of some politicians. -- Jim Pennino |
Antenna recommendation needed
On Sunday, January 18, 2015 at 8:16:04 PM UTC-6, wrote:
wrote: On Sunday, January 18, 2015 at 4:08:31 PM UTC-6, Bruno wrote: On Sun, 18 Jan 2015 21:28:07 +0000, jimp wrote: Verticals; if you have a lot of area, phased vertical arrays. Aren't verticals more inclined to generate interference? BTW, my plot is 120' by 90' so I think an array at HF will be impossible. The feed point will be pretty much central to the plot, though. I would probably string up parallel coax fed dipoles and have them at the low height. IE: 18-20 feet off the ground if that's all you can do. They will still work fairly well overall. Say if you can stick a short 1-2 ft stub mast on the roof, run dipoles from it, and feed with a single coax for both bands. Run the legs out to wherever you can tie them off. IE: trees, or short masts in the back yard/garden, etc. Won't be a gang buster DX setup, but plenty good enough for general use. With 40 and 20 dipoles, you would also have 15 meters, running the 40 legs. And you can feed more dipoles from the same coax if you want more bands. Using the coax as a feed line, no tuner required and low system losses. And also no need to worry about laying out radials. At that height most of the energy goes straight up, so it will be a NVIS antenna mostly suited for short ranges. -- Jim Pennino Sure. But it will still be able to work some DX, particularly on 20m, and 15m using the 40 legs. I guess it depends a lot on the type of operating he does. If he wants general purpose, and maybe more leaning to NVIS for 40m rag chewing, I'd go the dipole. If he wants DX over NVIS, he may well be better off with a vertical. But even a low dipole can be fairly good on the higher bands. I remember camping once with a 40m dipole about 8-10ft off the ground, and having no trouble working JA's on 15m using the same low antenna. For 40m NVIS within 500 miles or so, the low dipole will likely smoke most verticals. I've run so many low dipoles, I can't count them all. Never had trouble operating with any of them. And the setup is fairly simple. The thing about verticals, they tend to be fairly lackluster for closer in work on the lower bands. And I work much more rag chew NVIS type stuff than DX. I'm actually not interested in DX much at all any more. Been there, done that.. So it's kind of boring to me these days.. I tend to mostly jibber jabber to people I know these days, and work mostly close in 160/80/40.. Which for my type of operating, the dipoles usually do a good bit better than the verticals, even if fairly low. I guess he'll have to decide what he wants to lean to. Whatever he decides is unlikely to excel at both, and will be a compromise. |
Antenna recommendation needed
"Bruno" wrote in message ... Hi all, I've had a planning application for a tower turned down which is a real pain. My options are now very limited. I'm in a bungalow with a roof apex height of 18 feet and I'm not allowed to put up anything much above this roof line it transpires, so inverted vees that need to be mounted high up at the feed point like G5RVs are not possible for me. My garden boundaries limit the length of any wire antenna I might wish to put up to about 120 feet overall. On the plus side, though, the QTH is several hundred feet ASL close to the top of the hill and am not overshadowed by any trees or buildings to speak of. What's my best choice for an HF antenna under these circs? (I mostly do CW on 20m & 40m, but would like a bit more band choice ideally if poss). Many thanks. You will not need a tower, just a pole to support a HEX Beam. It is basically a 2 element beam and they seem to work very well at heigths of around 20 feet. Most are from 20 meters up, so a wire dipole for 80 and 40 metes will probably be needed also. A trapped dipole will shorten it up slightly . |
Antenna recommendation needed
Ralph Mowery wrote:
"Bruno" wrote in message ... Hi all, I've had a planning application for a tower turned down which is a real pain. My options are now very limited. I'm in a bungalow with a roof apex height of 18 feet and I'm not allowed to put up anything much above this roof line it transpires, so inverted vees that need to be mounted high up at the feed point like G5RVs are not possible for me. My garden boundaries limit the length of any wire antenna I might wish to put up to about 120 feet overall. On the plus side, though, the QTH is several hundred feet ASL close to the top of the hill and am not overshadowed by any trees or buildings to speak of. What's my best choice for an HF antenna under these circs? (I mostly do CW on 20m & 40m, but would like a bit more band choice ideally if poss). Many thanks. You will not need a tower, just a pole to support a HEX Beam. It is basically a 2 element beam and they seem to work very well at heigths of around 20 feet. Most are from 20 meters up, so a wire dipole for 80 and 40 metes will probably be needed also. A trapped dipole will shorten it up slightly . 20 feet is just a bit less than a half wave at 20 M, so a HEX beam (or any horizontal antenna) will work fairly well at that height. For the bands above 20 M you are above a half wave length. A dipole for 40 or 80 meters at 20 feet will radiate straight up, which is OK if you are only interested in local communications. FYI miltary NVIS communications useually takes place on 2-4 MHz at night and 5-7 MHz during the day. -- Jim Pennino |
Antenna recommendation needed
wrote in message ... A dipole for 40 or 80 meters at 20 feet will radiate straight up, which is OK if you are only interested in local communications. FYI miltary NVIS communications useually takes place on 2-4 MHz at night and 5-7 MHz during the day. At one house I lived in all I could put up was an 80 meter dipole at just under 20 feet. The center was supported by two pieces of electrical pvc type pipe. It had a good signal out to about 300 or so miles, and less at other distances. Worked fine at the time to talk to some locals to 300 miles in the eairly mornings. When limiated as to what you can do, just stick up something to start with and later work on getting something beter. |
Antenna recommendation needed
On 2015-01-18, Bruno wrote:
pain. My options are now very limited. I'm in a bungalow with a roof apex height of 18 feet and I'm not allowed to put up anything much above this roof line it transpires, so inverted vees that need to be mounted high up 1. You might want to take a look at Ian Poole's "Practical Wire Antennas". He is English and quite a few shorter antennas for use in the English back gardens. 2. Also this might give you some ideas: http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=28612 3. Having given those two, I've been very successful on portable and in backyard with an end-fed half wave wire. You will need a separate wire for each band, but the 40m wire (abt 67ft) will work for 20m as well. If you need 30m, just put up another wire. The reactance of the half wave wires is about the same (3000-5000 ohms) and can be tuned by any tuner capable of those impediances. I built (see website in signature block below) a tuner for half waves which is toroid based and one cap in parallel. You only have the one cap to tune since about the same reactance for each band. Now the best part: with end fed half waves you only need about .05 wavelength for the counterpoise, or about 7ft for 40m. Thin wire will be noticed by no one, especially if dark in color. :) Hope these suggestions help. ....Edwin __________________________________________________ __________ "Once you have flown, you will walk the earth with your eyes turned skyward, for there you have been, there you long to return."-da Vinci http://www.kd5zlb.org |
Antenna recommendation needed
wrote in message ... Ralph Mowery wrote: "Wayne" wrote in message ... If you can handle a 30 foot vertical (advertised by MFJ and others) it might work well with a good ground. If the real estate is limited for ground wires, just do the best you can, and live with it. If your restrictions do not allow a permanent 30 foot vertical, you might get permission to tilt it down when not in use. I have worked a few stations on 20 M that are using a vertical about 43 feet tall. I think that will exceed the heigth that can be installed at that location, but if not, something to think about. If the band is in good shape, it is possiable to work with minimal antennas. I have worked many mobile stations with the screwdriver antennas on 20 meters and they had very good signals. # Hustler # 4BTV 20 feet, 40, 20, 15, 10 $159 # 5BTV 23 feet, 80, 40, 20, 15, 10 $189 # 6BTV 24 feet, 80, 40, 30, 20, 15, 10 $209 # DXEnginerring Tilt Base mounting system: $61 to $106 depending on # frills. # How much for a tower, installation, and antennas? # A 43 foot vertical with an ATU at the base will run 160 to 10 meters. # There is no city in the US that regulates pounding a piece of pipe in # the ground and putting a BTV series antenna on top of it in your back # yard. # Well, I probably shouldn't say "no" given the flakyness of some politicians. My particular "regulations" were not by the city, but by deed restrictions not specifically listed on the deed, but on a document filed with the city that was referenced in the deed as being related to water, electric and sewer easements. I don't live in that city any more, and my current limitations have to do with a very small yard, and very short trees. |
Antenna recommendation needed
On 18/01/2015 20:55, Bruno wrote:
Hi all, I've had a planning application for a tower turned down which is a real pain. My options are now very limited. I'm in a bungalow with a roof apex height of 18 feet and I'm not allowed to put up anything much above this roof line it transpires, so inverted vees that need to be mounted high up at the feed point like G5RVs are not possible for me. My garden boundaries limit the length of any wire antenna I might wish to put up to about 120 feet overall. On the plus side, though, the QTH is several hundred feet ASL close to the top of the hill and am not overshadowed by any trees or buildings to speak of. What's my best choice for an HF antenna under these circs? (I mostly do CW on 20m & 40m, but would like a bit more band choice ideally if poss). Many thanks. Many thanks. Your QTH is virtually identical to mine - max height of 18 foot, longest clear run about 85 foot. I use a doublet - just two 57 foot wires forming the radiator/feeder. The ATU is 16 turns on a two inch former, tuned by a 250pF variable and link coupled (about 7 turns) to the rig via a 1000pF variable. This tunes/matches 80, 60, 40 and 20m. The two capacitors are actually double 500pF caps - one with sections in series, the other with sections in parallel. If local interference is an issue it is important to keep the radiating section as straight and as horizontal as possible. PA |
Antenna recommendation needed
On Monday, January 19, 2015 at 12:31:04 AM UTC-6,
For 40m NVIS within 500 miles or so, the low dipole will likely smoke most verticals. Of course it will as all the energy will go straight up while the vertical main lobe is at about 30 degrees. The important factor is the height in wavelengths, not feet. As the height drops below a half wavelength the main lobe goes vertical on a dipole (or any horizontal antenna) rapidly. Sure, but there is still enough at the low angles to make some DX contacts. And he'll have a decent signal to the stations not so far away on 40m. I guess he'll have to decide what he wants to lean to. Whatever he decides is unlikely to excel at both, and will be a compromise. If local communications is your goal, then an NVIS antenns is what you want. However as the frequency increases above about 8 MHz the probablity for success decreases and drops to near zero at 30 MHz. For 20 meters it is a crap shoot with less than good sunspot activity. The performance at low angles won't be quite as grim as you might expect. IE: I had no trouble working 15m DX with a -10 ft high dipole. 20 ft up is nearly a 1/2 on 15m. And a 20m dipole at 20 ft will be quite decent for average use being over a 1/4 wave up. Will be good stateside, and usable for DX. I like converted CB ground planes for 10m. Good space wave for local, and good for DX. Not much close in sky wave stuff to work on that band. I don't really see how a dipole requiring three supports, two at best, can be considered simpler than a vertical with one support. A vertical generally needs radials unless it's a "1/2 wave" type design. And even good verticals can be quite lackluster for close in work compared to a low dipole on 40m. Good at night to DX though. But like I say, he's gotta decide what he wants to concentrate on, and go from there. If he has trees to tie dipole legs to, he really only needs one support for the apex. And one can also string them between trees to where no man made supports are needed at all. But I don't know what trees he has available. I usually have one mast for the apex, and tie off to trees or whatever. At the dirt patch, I use a oak tree as the apex support, and tie off to other trees. I shoot a weighted line up into the apex tree, and run it over a tall branch. Then I pull the dipole and coax back up into the tree with the wire I shot over the tall branch. When I go home, I let the wire loose, and back down it all falls. I used to leave it there all the time, but the critters were eating my coax into shreds, so I had to quit that. :/ And the tuner/ladder line fed dipoles is another option if one wants all bands with one antenna. |
Antenna recommendation needed
On 18/01/15 20:55, Bruno wrote:
I've had a planning application for a tower turned down which is a real pain. My options are now very limited. I'm in a bungalow with a roof apex height of 18 feet and I'm not allowed to put up anything much above this roof line it transpires, so inverted vees that need to be mounted high up at the feed point like G5RVs are not possible for me. My garden boundaries limit the length of any wire antenna I might wish to put up to about 120 feet overall. On the plus side, though, the QTH is several hundred feet ASL close to the top of the hill and am not overshadowed by any trees or buildings to speak of. What's my best choice for an HF antenna under these circs? You could have two...a horizontal, as suggested by others, and then there's this.... Consider is using the slope of the hill to your advantage. How close to it are you? Over what arc of the compass does the slope cover? My thinking is that you should consider ground-mounting a vertical as close to the slope as possible. The down-slope will pull down the vertical radiation lobe to perhaps all but the horizontal, giving you effective gain over a vertical operating over level ground together with the prospect of long hop-length DX from the low angle. The difference in gain can be useful to significant., and the reduced number of hops can reduce path losses. Get a great-circle map and see what sector of the world is covered by the arc of the slope; you'll get the best reports from within this arc. The vertical need not be high at all. For the lower bands you could try the following set-up; you could make it in an hour or so. An auto-tuner would make this a breeze, but you can put together the following from your junk box. Wind a coil having an inductance of 0.25 x lambda for the band of interest. For 40m this would be 0.25 x 40 = 10 microH. I make my coils from flex stripped from scrap mains cable. You'll also need a variable capacitor of about 1pF per lambda, but this isn't critical. Connect this across the coil. Wind on a 4-turn link at the 'bottom' end of the coil connected to 50 ohm coax and connect to your rig. To the 'top' end of the coil, connect your vertical. Mine is 18' of wire taped to a roach pole, for the lower bands. To the bottom end connect four radials, each as long as the vertical is high. Connect to a screwdriver or very short rod earth via an RF choke or 1k resistor. Do not bury the radials or connect a massive earth, this one is to bleed static, nothing more. The radials will couple the RF to ground. It's my experience that when the length of the vertical becomes a significant fraction of the wavelength (say 1/10th), the system begins not to work so well - the solution is to tap the aerial connection down the coil, but this adds complexity. Keep the vertical section short and enjoy the simplicity. This is a try-out of the possibilities of your QTH, after all. I find that this set-up is very non-critical, and with a 200pF variable and the right inductance it will tune over two bands, say 160/80, or 80/60/40. Above these bands the link's turns will need to be reduced and the system self-capacitance can be a nuisance, so perhaps an auto-tuner would be better. Your output power will be limited by the capacitor's capability voltage-wise. The only drawback is retuning for each band, as the tuner is located at the base of the antenna. I use mine in the portable mode, so operating near the base of the antenna isn't a problem. Using a similar set-up on a short (200') slope facing East, I can work all of Russia, the Mediterranean, and Asia from the UK with good reports and running less than 10W, on 17 and above (for which I use an auto-tuner). I don't work 20m, never liked the band much, and below that, the slope isn't really long enough to pull the vertical lobe down. Hopefully, yours will be. -- Spike "Hard cases, it has frequently been observed, are apt to introduce bad law". Judge Rolfe |
Antenna recommendation needed
|
Antenna recommendation needed
|
Antenna recommendation needed
On 1/20/2015 12:30 PM, wrote:
wrote: snip A vertical generally needs radials unless it's a "1/2 wave" type design. And even good verticals can be quite lackluster for close in work compared to a low dipole on 40m. Good at night to DX though. But like I say, he's gotta decide what he wants to concentrate on, and go from there. You are all over the place here and mixing apples and oranges. In what way? Seems perfectly reasonable and informative to me. A vertical has a low elevation angle. You will have to describe the conditions for that to be a truthful general statement. Do you mean ground mounted with buried radials, radials lying on the surface, elevated verticals with radials, or half-wave verticals with no radials? Any antenna that has a low elevation angle is "better" for distant communications than an antenna with a very high elevation angles. I think that is agreeable by all. A horizontal antenna less than a half wavelength in height has a vey high elevation angle. At .3 lambda it is 48 degrees, at .25 lambda it is 62 degrees, and at .2 lambda it is 90 degrees, i.e. straight up. According to the simulation programs, that is probably true. But, that is the angle of *maximum* radiation. How much signal is available at the 3dB, 6dB, 10dB, 20dB angles? If you are running 100 watts, you still have 1 watt available at the 20dB angle. This is called an NVIS antenna which is "better" for local communications out to about 500 miles or so on the lower bands. NVIS communcations is nearly nil much above 8 MHz at other than sunspot peaks. We are currently past the peak of the current sunspot cycle and heading for a minimum. Can you supply support to some other source for this conclusion? A vertical antenna does not "need" radials, but it's performance is improved by radials. It depends on the design. A vertical antenna over average ground has a main lobe at about 30 degees and a gain of about 1 dBi. Please supply configuration of the antenna as mentioned above. A vertical antenna over perfect ground has a main lobe at 0 degrees and a gain of about 5 dBi. Again, please supply configuration of the antenna as mentioned above. In a typical urban setting where there is landscaping and irrigation, the ground is most likely average to very good unless you are in the middle of a desert, which means even without radials the vertical's gain is going to be a few dBi. Adding a few radials will improve the gain and lower the main lobe but are not absolutely necessary. I think this is unsubstantiated unless you can supply supporting documentation. Most verticals will get put in the middle of a lawn and it is trivial to take a lawn edger or weed wacker and cut a groove in the grass down to the dirt and staple down some radials. In such a setting you do NOT need the 120 radials of a commercial broadcast station with it's antenna in a barren field. Most verticals will be installed depending on the installers resources, abilities, and present knowledge of antennas. If he has trees to tie dipole legs to, he really only needs one support for the apex. The bottom line is a horizontal antenna needs three supports. Actually, a 40 meter dipole can use two supports (trees) and can work the US easily with a 50W transmitter. snip |
Antenna recommendation needed
John S wrote:
On 1/20/2015 12:30 PM, wrote: wrote: snip A vertical generally needs radials unless it's a "1/2 wave" type design. And even good verticals can be quite lackluster for close in work compared to a low dipole on 40m. Good at night to DX though. But like I say, he's gotta decide what he wants to concentrate on, and go from there. You are all over the place here and mixing apples and oranges. In what way? Seems perfectly reasonable and informative to me. A vertical has a low elevation angle. You will have to describe the conditions for that to be a truthful general statement. Do you mean ground mounted with buried radials, radials lying on the surface, elevated verticals with radials, or half-wave verticals with no radials? Most people mean ground mounted when they use the term vertical and ground plane for an elevated vertical. I meant ground mounted and the radials or lack of them is essentially irrelevant. Any antenna that has a low elevation angle is "better" for distant communications than an antenna with a very high elevation angles. I think that is agreeable by all. I would certainly hope so. A horizontal antenna less than a half wavelength in height has a vey high elevation angle. At .3 lambda it is 48 degrees, at .25 lambda it is 62 degrees, and at .2 lambda it is 90 degrees, i.e. straight up. According to the simulation programs, that is probably true. As well as basic physics. But, that is the angle of *maximum* radiation. How much signal is available at the 3dB, 6dB, 10dB, 20dB angles? If you are running 100 watts, you still have 1 watt available at the 20dB angle. I would be glad to run the numbers for you. Do you want it as a comparsion between a vertical with no radials, a vertical with radials, both over average ground, and a vertical with perfect ground? This is called an NVIS antenna which is "better" for local communications out to about 500 miles or so on the lower bands. NVIS communcations is nearly nil much above 8 MHz at other than sunspot peaks. We are currently past the peak of the current sunspot cycle and heading for a minimum. Can you supply support to some other source for this conclusion? I assume you mean for NVIS communications and not the sunspot cycle: http://en.wikipedia.org/wiki/Near_ve...idence_skywave http://www.w0ipl.net/ECom/NVIS/nvis.htm http://www.w5jck.com/nvis/W5JCK-NVIS...esentation.pdf https://www.txarmymars.org/.../NVIS-...and-Design.pdf http://www.qsl.net/wb5ude/nvis/ http://home.centurytel.net/w9wis/NVIS.html Want more? A vertical antenna does not "need" radials, but it's performance is improved by radials. It depends on the design. The design is a metal tube about .25 lambda long mounted close to the ground and fed at the bottom end. A vertical antenna over average ground has a main lobe at about 30 degees and a gain of about 1 dBi. Please supply configuration of the antenna as mentioned above. A metal tube about .25 lambda long mounted close to the ground and fed at the bottom end. A vertical antenna over perfect ground has a main lobe at 0 degrees and a gain of about 5 dBi. Again, please supply configuration of the antenna as mentioned above. A metal tube about .25 lambda long mounted close to the ground and fed at the bottom end. In a typical urban setting where there is landscaping and irrigation, the ground is most likely average to very good unless you are in the middle of a desert, which means even without radials the vertical's gain is going to be a few dBi. Adding a few radials will improve the gain and lower the main lobe but are not absolutely necessary. I think this is unsubstantiated unless you can supply supporting documentation. Trivially demonstrated by any antenna simulation program. Or are you looking for numbers on ground conductivity? Google ground conductivity Want to measure it yourself, read this: http://www.technik.dhbw-ravensburg.d...ductivity.html Most verticals will get put in the middle of a lawn and it is trivial to take a lawn edger or weed wacker and cut a groove in the grass down to the dirt and staple down some radials. In such a setting you do NOT need the 120 radials of a commercial broadcast station with it's antenna in a barren field. Most verticals will be installed depending on the installers resources, abilities, and present knowledge of antennas. The same can be said for making cookies; so what? One of the purposes of this group is the dissemination of antenna knowledge. I make no assumptions about the readers other than the ability to read. If he has trees to tie dipole legs to, he really only needs one support for the apex. The bottom line is a horizontal antenna needs three supports. Actually, a 40 meter dipole can use two supports (trees) and can work the US easily with a 50W transmitter. Sure, if you use very heavy wire for the dipole and very light feed line. BTW, most amateur rigs these days put out 100 Watts. -- Jim Pennino |
Antenna recommendation needed
On Tuesday, January 20, 2015 at 12:31:04 PM UTC-6, wrote:
wrote: snip A vertical generally needs radials unless it's a "1/2 wave" type design. And even good verticals can be quite lackluster for close in work compared to a low dipole on 40m. Good at night to DX though. But like I say, he's gotta decide what he wants to concentrate on, and go from there. You are all over the place here and mixing apples and oranges. Yes, because you are dealing with apples and oranges in the real world, and until he comes back and describes what mode of operation he prefers most of the time, I include both options. A vertical has a low elevation angle. And not much at the higher angles. Which will make it fairly poor compared to a low dipole when used for general 40m NVIS use, say in the daytime. Any antenna that has a low elevation angle is "better" for distant communications than an antenna with a very high elevation angles. Sure, but until he comes back and describes his usual mode of operation, I'm not sure if that is what he wants at all times. A horizontal antenna less than a half wavelength in height has a vey high elevation angle. At .3 lambda it is 48 degrees, at .25 lambda it is 62 degrees, and at .2 lambda it is 90 degrees, i.e. straight up. I've modeled and used antennas for many years.. I know the usual patterns of the various options. This is called an NVIS antenna which is "better" for local communications out to about 500 miles or so on the lower bands. NVIS communcations is nearly nil much above 8 MHz at other than sunspot peaks. We are currently past the peak of the current sunspot cycle and heading for a minimum. The angles used for 20m stateside can be fairly high. I know from experience that a 20m dipole at 20 ft will work quite well for average distances. It will be quite good within 1500 miles, and still quite usable at DX distances. It will generally be a good performing antenna for overall use. And if the band condx are heading down as you say, he would more likely be on 40 and 20, than the higher bands. Will he work 40m in the daytime? If so, he will want to be on the low dipole, rather than the vertical. Would be like comparing fresh cut oranges to rotten apples. :/ A vertical antenna does not "need" radials, but it's performance is improved by radials. Sure. But if he's over med to poor ground, the losses can be substantial. I'm over quite good ground being on the Gulf Coast, and I had a full size 32 ft tall 40m vertical ground mounted with 32 radials. It was OK, but no real DX buster. At all.. I then raised the antenna to 36 ft at the base, and used 4 sloping radials as a ground plane. That antenna absolutely smoked the ground mount antenna to DX. So the ground radials obviously were a factor, and I'm over pretty good ground. A vertical antenna over average ground has a main lobe at about 30 degees and a gain of about 1 dBi. And? A vertical antenna over perfect ground has a main lobe at 0 degrees and a gain of about 5 dBi. I don't know anyone who lives on perfect ground. :| In a typical urban setting where there is landscaping and irrigation, the ground is most likely average to very good unless you are in the middle of a desert, which means even without radials the vertical's gain is going to be a few dBi. Adding a few radials will improve the gain and lower the main lobe but are not absolutely necessary. That is true for the area I live on, and obviously the number of radials made quite a difference in my case. Raising the antenna let me use less radials to equal a certain number on the ground. I was using 32 on the ground for only so-so DX performance. The four I used at 36 ft were equal to about 60 or so on the ground at that height in wavelength on 40m. Most verticals will get put in the middle of a lawn and it is trivial to take a lawn edger or weed wacker and cut a groove in the grass down to the dirt and staple down some radials. In such a setting you do NOT need the 120 radials of a commercial broadcast station with it's antenna in a barren field. I'd want a decent number to really brown the food. And you have to consider the price of wire these days. Copper wire can add up to $$$$. If he has trees to tie dipole legs to, he really only needs one support for the apex. The bottom line is a horizontal antenna needs three supports. Not if you use two supports for the whole antenna, and let the feed line drop from the center down to the ground and then to the shack. He doesn't actually have to let it drop to the ground, but in the case of coax fed, I prefer that in case of a lightning strike. And snubbing the shield to a ground stake at that point, even better. I like metal masts as an apex support, as it will usually take the strike and route it to ground, instead of the antenna, as long as the mast extends slightly over the feed point of the antenna. snip And the tuner/ladder line fed dipoles is another option if one wants all bands with one antenna. As is a vertical piece of aluminum tubing of whatever height you can put up with an ATU at the base of it. Sure, I never said it wasn't. Almost a gazillion options in the wide wide world of antennas. :) But until he comes back and describes his usual mode of operation, I feel it's best to include all options, and not just limit it to verticals. |
Antenna recommendation needed
On Tue, 20 Jan 2015 16:09:25 +0000, Spike wrote:
How close to it are you? Over what arc of the compass does the slope cover? Good point. I'd forgot to specify that. I'm about fairly close to the summit and the ground drops away mainly to the SSE with the coast about a mile away. From here I can see couple of miles out to sea. Since I'm in the centre of the British Isles, I'm in a great position for getting good signals to and from South Africa - but not really anywhere else! :-( |
Antenna recommendation needed
wrote:
On Tuesday, January 20, 2015 at 12:31:04 PM UTC-6, wrote: wrote: snip A vertical generally needs radials unless it's a "1/2 wave" type design. And even good verticals can be quite lackluster for close in work compared to a low dipole on 40m. Good at night to DX though. But like I say, he's gotta decide what he wants to concentrate on, and go from there. You are all over the place here and mixing apples and oranges. Yes, because you are dealing with apples and oranges in the real world, and until he comes back and describes what mode of operation he prefers most of the time, I include both options. What he prefers is irrelevant to a general discussion about how antennas work. A vertical has a low elevation angle. And not much at the higher angles. Which will make it fairly poor compared to a low dipole when used for general 40m NVIS use, say in the daytime. Obviously. Any antenna that has a low elevation angle is "better" for distant communications than an antenna with a very high elevation angles. Sure, but until he comes back and describes his usual mode of operation, I'm not sure if that is what he wants at all times. What he prefers is irrelevant to a general discussion about how antennas work. A horizontal antenna less than a half wavelength in height has a vey high elevation angle. At .3 lambda it is 48 degrees, at .25 lambda it is 62 degrees, and at .2 lambda it is 90 degrees, i.e. straight up. I've modeled and used antennas for many years.. I know the usual patterns of the various options. This is called an NVIS antenna which is "better" for local communications out to about 500 miles or so on the lower bands. NVIS communcations is nearly nil much above 8 MHz at other than sunspot peaks. We are currently past the peak of the current sunspot cycle and heading for a minimum. The angles used for 20m stateside can be fairly high. I know from experience that a 20m dipole at 20 ft will work quite well for How high in wavelengths is 20 feet at 20M and how does that relate to what I have already said about antenna height? average distances. It will be quite good within 1500 miles, and still quite usable at DX distances. It will generally be a good performing antenna for overall use. And if the band condx are heading down as you say, he would more likely be on 40 and 20, than the higher bands. I said we are heading for a sunspot minimum, which means that NVIS communications is gettting more and more unlikely above 8 MHz. Will he work 40m in the daytime? If so, he will want to be on the low dipole, rather than the vertical. Would be like comparing fresh cut oranges to rotten apples. :/ What he prefers is irrelevant to a general discussion about how antennas work. A vertical antenna does not "need" radials, but it's performance is improved by radials. Sure. But if he's over med to poor ground, the losses can be substantial. I'm over quite good ground being on the Gulf Coast, and I had a full size 32 ft tall 40m vertical ground mounted with 32 radials. It was OK, but no real DX buster. At all.. If, if, if. The reality is most people live on average to good ground if for no other reason than they landscape it. I then raised the antenna to 36 ft at the base, and used 4 sloping radials as a ground plane. That antenna absolutely smoked the ground mount antenna to DX. So the ground radials obviously were a factor, and I'm over pretty good ground. The biggest factor is that you elevated it. Here are the numbers for a ground plane with 45 degree radials for various heights: Height is in wavelengths above ground for the bottom of the radials and @ elev is the elevation angle of the main lobe. Height gain @ elev 0.01 0.78 21 0.10 1.32 18 0.15 1.50 17 0.20 1.59 15 0.25 1.63 15 0.30 1.63 14 0.35 1.62 13 0.40 1.63 13 0.45 2.02 43 0.50 2.37 40 0.55 2.64 38 0.60 2.86 36 0.65 3.03 34 0.70 3.15 32 0.75 3.21 30 0.80 3.22 29 0.85 3.18 27 0.90 3.16 9 0.95 3.29 9 1.00 3.42 9 1.05 3.54 9 1.10 3.67 9 1.15 3.81 8 1.20 3.95 8 1.25 4.07 8 A vertical antenna over average ground has a main lobe at about 30 degees and a gain of about 1 dBi. And? And it is a fact. A vertical antenna over perfect ground has a main lobe at 0 degrees and a gain of about 5 dBi. I don't know anyone who lives on perfect ground. :| Neither do I but it is the reference for being as good as one can get, i.e. the best you could possible do with a huge number of radials. In a typical urban setting where there is landscaping and irrigation, the ground is most likely average to very good unless you are in the middle of a desert, which means even without radials the vertical's gain is going to be a few dBi. Adding a few radials will improve the gain and lower the main lobe but are not absolutely necessary. That is true for the area I live on, and obviously the number of radials made quite a difference in my case. Raising the antenna let me use less radials to equal a certain number on the ground. I was using 32 on the ground for only so-so DX performance. The four I used at 36 ft were equal to about 60 or so on the ground at that height in wavelength on 40m. Which is, for a lot of people, a well known phenomenon. You get more gain by elevating the antenna. You also have the effect that 4 elevated radials, even if only elevated a very small distance, are equivelant to a great number of buried radials, i.e. more closely approximates the perfect ground that doesn't exist. Most verticals will get put in the middle of a lawn and it is trivial to take a lawn edger or weed wacker and cut a groove in the grass down to the dirt and staple down some radials. In such a setting you do NOT need the 120 radials of a commercial broadcast station with it's antenna in a barren field. I'd want a decent number to really brown the food. And you have to consider the price of wire these days. Copper wire can add up to $$$$. 14 AWF THHN wire brand new from Lowes costs about $0.09/foot and will work just fine for radials. If you are really cheap, you can find surplus wire at swap meets for much less than that. If he has trees to tie dipole legs to, he really only needs one support for the apex. The bottom line is a horizontal antenna needs three supports. Not if you use two supports for the whole antenna, and let the feed line drop from the center down to the ground and then to the shack. He doesn't actually have to let it drop to the ground, but in the case of coax fed, I prefer that in case of a lightning strike. And snubbing the shield to a ground stake at that point, even better. I like metal masts as an apex support, as it will usually take the strike and route it to ground, instead of the antenna, as long as the mast extends slightly over the feed point of the antenna. Sure, like I said and which you snipped, if you use heavy wire for the dipole and a light feed line. You are still at at least two supports. snip And the tuner/ladder line fed dipoles is another option if one wants all bands with one antenna. As is a vertical piece of aluminum tubing of whatever height you can put up with an ATU at the base of it. Sure, I never said it wasn't. Almost a gazillion options in the wide wide world of antennas. :) But until he comes back and describes his usual mode of operation, I feel it's best to include all options, and not just limit it to verticals. What he prefers is irrelevant to a general discussion about how antennas work. And I did NOT limit the discussion to verticals, I compared low mounted horizontal antennas to vertical antennas. -- Jim Pennino |
Antenna recommendation needed
On Tuesday, January 20, 2015 at 4:16:04 PM UTC-6,
Yes, because you are dealing with apples and oranges in the real world, and until he comes back and describes what mode of operation he prefers most of the time, I include both options. What he prefers is irrelevant to a general discussion about how antennas work. This is not a general discussion about how antennas work. Myself, I already know how antennas work. These are replies to him asking for recommendations for antennas to fit the room and lot he has. And what type of operation he prefers to do is a large part of knowing the best antennas to recommend, and is totally relevant. He may well prefer DX, but on the other hand, he may well prefer general rag chew type work closer in. We haven't heard from him about that part yet, so I don't have a clue on that part. And I did NOT limit the discussion to verticals, I compared low mounted horizontal antennas to vertical antennas. I already know how low mounted horizontal antennas compare to verticals, both by modeling, and many real world comparisons. But this discussion is not about me, or what I may or may not know. |
Antenna recommendation needed
On 20/01/15 21:40, Bruno wrote:
On Tue, 20 Jan 2015 16:09:25 +0000, Spike wrote: How close to it are you? Over what arc of the compass does the slope cover? Good point. I'd forgot to specify that. I'm about fairly close to the summit and the ground drops away mainly to the SSE with the coast about a mile away. From here I can see couple of miles out to sea. Since I'm in the centre of the British Isles, I'm in a great position for getting good signals to and from South Africa - but not really anywhere else! :-( What a beautiful part of the country! Many decades ago my parents retired to live in a small village on the River Lune. Pity about the take-off from your site :-( but the lower bands might be well workable via a vertical. Use a horizontal for NVIS, and keep your fingers crossed for some DX. -- Spike "Hard cases, it has frequently been observed, are apt to introduce bad law". Judge Rolfe |
Antenna recommendation needed
|
Antenna recommendation needed
On Tue, 20 Jan 2015 23:22:46 +0000, Spike wrote:
On 20/01/15 21:40, Bruno wrote: On Tue, 20 Jan 2015 16:09:25 +0000, Spike wrote: How close to it are you? Over what arc of the compass does the slope cover? Good point. I'd forgot to specify that. I'm about fairly close to the summit and the ground drops away mainly to the SSE with the coast about a mile away. From here I can see couple of miles out to sea. Since I'm in the centre of the British Isles, I'm in a great position for getting good signals to and from South Africa - but not really anywhere else! :-( What a beautiful part of the country! Many decades ago my parents retired to live in a small village on the River Lune. Pity about the take-off from your site :-( but the lower bands might be well workable via a vertical. Use a horizontal for NVIS, and keep your fingers crossed for some DX. Ok, understood. Well, I have more than enough info to be going on with for the time being so many thanks to all who contributed to this thread and assisted in clarifying my choices very effectively! Bruno |
| All times are GMT +1. The time now is 03:00 PM. |
Powered by vBulletin® Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
RadioBanter.com