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10m - 40m non resonant vertical
Dear group,
As a temporarily solution I would like to use a cheap 5/8, 6/8 or 7/8 WL commercially available CB antenna as a non resonant vertical with elevated radials for use on 10 - 40 meters tuned by an automatic remote ATU at the base of the antenna. I used MMANA and EZNEC (demo) to calculate the expected impedance for the frequency range and found too many results for the height of the antenna. Now I am confused about what to select. Is 5/8WL on 10meters a good height or 8 meter (22')? What I want is a low take off angle on 20 and 30 meters with high efficiency and an impedance which my remote ATU can handle. Fred, PA0FVH |
10m - 40m non resonant vertical
Fred PA0FVH wrote:
Dear group, As a temporarily solution I would like to use a cheap 5/8, 6/8 or 7/8 WL commercially available CB antenna as a non resonant vertical with elevated radials for use on 10 - 40 meters tuned by an automatic remote ATU at the base of the antenna. I used MMANA and EZNEC (demo) to calculate the expected impedance for the frequency range and found too many results for the height of the antenna. Now I am confused about what to select. Is 5/8WL on 10meters a good height or 8 meter (22')? What I want is a low take off angle on 20 and 30 meters with high efficiency and an impedance which my remote ATU can handle. Fred, PA0FVH To a first order, you just want to avoid lengths where it's close to a half wavelength (assuming you're using an ATU that's designed for this sort of application) because that's where the Z is highest and toughest to match. The low Z points are going to be easy (a few tens of ohms, and almost any tuner can do that). So, the lowest frequency where this is the case is where the wavelength is 16m... straddling the 15 and 17m bands. In practice, what you might need to do is adjust the length of the antenna by a few tens of cm one way or the other to find a place where your tuner is happy. Another situation is where the antenna is a full wavelength.. but 8m is higher than the 10m ham band, so you're probably ok. The other problem is if the reactive component gets too far for your tuner to handle, but without knowing the tuning range of your tuner, that's hard to know. |
10m - 40m non resonant vertical
"Fred PA0FVH" wrote in message ... Dear group, As a temporarily solution I would like to use a cheap 5/8, 6/8 or 7/8 WL commercially available CB antenna as a non resonant vertical with elevated radials for use on 10 - 40 meters tuned by an automatic remote ATU at the base of the antenna. I used MMANA and EZNEC (demo) to calculate the expected impedance for the frequency range and found too many results for the height of the antenna. Now I am confused about what to select. Is 5/8WL on 10meters a good height or 8 meter (22')? What I want is a low take off angle on 20 and 30 meters with high efficiency and an impedance which my remote ATU can handle. Fred, PA0FVH Hi Fred, The first thing to understand is that for the most part the CB 5/8, 6/8, 7/8 antennas have nothing to do with the actual height. Manufacturers started claiming these lengths because the CBers believe(d) longer is better. At least for the mobile antennas the 5/8 etc referred more to the length of the wire used in the antenna- electrically, they were all 1/4 wavelength antennas. Dale W4OP |
10m - 40m non resonant vertical
Dale Parfitt wrote:
... Hi Fred, The first thing to understand is that for the most part the CB 5/8, 6/8, 7/8 antennas have nothing to do with the actual height. Manufacturers started claiming these lengths because the CBers believe(d) longer is better. At least for the mobile antennas the 5/8 etc referred more to the length of the wire used in the antenna- electrically, they were all 1/4 wavelength antennas. Dale W4OP The ones you looked at, it seems, were all 1/4 wavelength physically ... electrically? So, in you book, you can have a 1 foot, foot -- a 2 foot, foot -- a 4 foot, foot --- etc.? Regards, JS |
10m - 40m non resonant vertical
On Tue, 9 Dec 2008 23:11:10 +0100, "Fred PA0FVH"
wrote: Dear group, As a temporarily solution I would like to use a cheap 5/8, 6/8 or 7/8 WL commercially available CB antenna as a non resonant vertical with elevated radials for use on 10 - 40 meters tuned by an automatic remote ATU at the base of the antenna. I used MMANA and EZNEC (demo) to calculate the expected impedance for the frequency range and found too many results for the height of the antenna. Now I am confused about what to select. Is 5/8WL on 10meters a good height or 8 meter (22')? What I want is a low take off angle on 20 and 30 meters with high efficiency and an impedance which my remote ATU can handle. Hi Fred, 6/8th and 7/8th wavelength at 10M would not have the best low angle charateristic. At the longer wavelengths it should get progressively better (as you may tell from EZNEC demo). 7/8th wavelength at 10M may also be hard to match with your ATU, but worth a try. Shorter antennas for longer wavelengths may find more loss in the ATU than you would care to have, but a 5/8ths at 10M might be the best work-around; and the shortest you should go. 73's Richard Clark, KB7QHC |
10m - 40m non resonant vertical
Hi Guys,
Thanks for your good suggestions. The first thing to understand is that for the most part the CB 5/8, 6/8, 7/8 antennas have nothing to do with the actual height. Manufacturers started claiming these lengths because the CBers believe(d) longer is better The physical length of those antennas available over here are 6.5m, 9.1m and 9.5m. So any height between 6.5m and 9.5m would be possible. It is an alternative for going to a DIY store to get aluminum tubing. The other problem is if the reactive component gets too far for your tuner to handle, but without knowing the tuning range of your tuner, that's hard to know. My remote ATU (Pi matching) has an inductance range from 0 to 63uH and the capacitance ranges from 0 to 6300pF Fred, PA0FVH |
10m - 40m non resonant vertical
"Fred PA0FVH" wrote in message ... Dear group, As a temporarily solution I would like to use a cheap 5/8, 6/8 or 7/8 WL commercially available CB antenna as a non resonant vertical with elevated radials for use on 10 - 40 meters tuned by an automatic remote ATU at the base of the antenna. I used MMANA and EZNEC (demo) to calculate the expected impedance for the frequency range and found too many results for the height of the antenna. Now I am confused about what to select. Is 5/8WL on 10meters a good height or 8 meter (22')? What I want is a low take off angle on 20 and 30 meters with high efficiency and an impedance which my remote ATU can handle. Fred, PA0FVH ------------ Obtain a Solarcon A99. It will behave exactly as you have described, even with a built-in tuner. BTDT. Put it up about 20'. It will suck on 40 meters, but it will work. 20 meters isn't the best either, but it is usable. 17 meters on up it will work very well. With 100 watts I could work 15 & 17 meters into Europe from NJ in the USA, with headroom to spare. Yes, the bands were open, but they were crowded at the time. I worked Austria as though they were next door. Ed, N2ECW |
10m - 40m non resonant vertical
Fred PA0FVH wrote:
Is 5/8WL on 10meters a good height or 8 meter (22')? What I want is a low take off angle on 20 and 30 meters with high efficiency and an impedance which my remote ATU can handle. Yes, you don't want to get much longer than 5/8WL on 10m and you don't want to get much shorter than 3/16WL on 40m. 22 feet is a good compromise length. At my previous QTH I used a 22' monopole with the feedpoint elevated at 22' with four 22' radials sloping down at 45 degrees (also used as guy wires) and fed with an SG-230. It worked like a charm for transmitting - noisy on receive. Here's some information from simulations: 22' Monopole with 22' elevated sloping radials: Band: Gain: Take Off Angle: Feedpoint: ~Tuner Loss 40m: 0.53 dBi: 22 deg: 24-j229 ohms: 0.9 dB 30m: 0.94 dBi: 19 deg: 46-j31 ohms: 0.2 dB 20m: 1.47 dBi: 16 deg: 128+j233 ohms: 0.1 dB 17m: 1.91 dBi: 14 deg: 556+j583 ohms: 0.2 dB 15m: 2.47 dBi: 12 deg: 1315-j372 ohms: 0.3 dB 12m: 3.40 dBi: 13 deg: 373-j560 ohms: 0.3 dB 10m: 4.21 dBi: 11 deg: 885-j290 ohms: 0.2 dB -- 73, Cecil http://www.w5dxp.com |
10m - 40m non resonant vertical
FWIW, http://dixienc.us/28FtVert/28FtVertical.htm
might help you make some decisions. Unless you already have the materials I suggest you build with ten foot lengths of chain link top rail. The last time I priced it at the home improvement store it was $11 per section. If it were not for the price of the tuner it would be a cheap antenna. Every time I tinker with it I learn a little more. If DX is your thing, go for the low angle radiation for your favored band. DX is of little interest to me so the high angle radiation on some bands just gives me a different set of Hams to work. John Ferrell W8CCW On Tue, 9 Dec 2008 23:11:10 +0100, "Fred PA0FVH" wrote: Dear group, As a temporarily solution I would like to use a cheap 5/8, 6/8 or 7/8 WL commercially available CB antenna as a non resonant vertical with elevated radials for use on 10 - 40 meters tuned by an automatic remote ATU at the base of the antenna. I used MMANA and EZNEC (demo) to calculate the expected impedance for the frequency range and found too many results for the height of the antenna. Now I am confused about what to select. Is 5/8WL on 10meters a good height or 8 meter (22')? What I want is a low take off angle on 20 and 30 meters with high efficiency and an impedance which my remote ATU can handle. Fred, PA0FVH |
10m - 40m non resonant vertical
John Ferrell wrote:
FWIW, http://dixienc.us/28FtVert/28FtVertical.htm might help you make some decisions. Unless you already have the materials I suggest you build with ten foot lengths of chain link top rail. The last time I priced it at the home improvement store it was $11 per section. If it were not for the price of the tuner it would be a cheap antenna. Every time I tinker with it I learn a little more. If DX is your thing, go for the low angle radiation for your favored band. DX is of little interest to me so the high angle radiation on some bands just gives me a different set of Hams to work. John Ferrell W8CCW Hmmm, in "Kalifornia" (we tend towards actors to play the part of governors, here) "high angle" seems to give me the east coast; While, low angle tends to give me the Aussies ... DX isn't the east coast? Regards, JS |
10m - 40m non resonant vertical
On Dec 10, 7:50*am, Cecil Moore wrote:
Fred PA0FVH wrote: Is 5/8WL on 10meters a good height or 8 meter (22')? What I want is a low take off angle on 20 and 30 meters with high efficiency and an impedance which my remote ATU can handle. Yes, you don't want to get much longer than 5/8WL on 10m and you don't want to get much shorter than 3/16WL on 40m. 22 feet is a good compromise length. At my previous QTH I used a 22' monopole with the feedpoint elevated at 22' with four 22' radials sloping down at 45 degrees (also used as guy wires) and fed with an SG-230. It worked like a charm for transmitting - noisy on receive. Here's some information from simulations: 22' Monopole with 22' elevated sloping radials: Band: Gain: Take Off Angle: Feedpoint: ~Tuner Loss 40m: 0.53 dBi: 22 deg: * 24-j229 ohms: 0.9 dB 30m: 0.94 dBi: 19 deg: * *46-j31 ohms: 0.2 dB 20m: 1.47 dBi: 16 deg: *128+j233 ohms: 0.1 dB 17m: 1.91 dBi: 14 deg: *556+j583 ohms: 0.2 dB 15m: 2.47 dBi: 12 deg: 1315-j372 ohms: 0.3 dB 12m: 3.40 dBi: 13 deg: *373-j560 ohms: 0.3 dB 10m: 4.21 dBi: 11 deg: *885-j290 ohms: 0.2 dB -- 73, Cecil *http://www.w5dxp.com Experimenting with a too long antenna on 10M can be fun. I did a 1.25 wl antenna and got some interesting results during band openings. You get to talk to where everyone else isnt. I felt like the band had opened just for me. Of course this isnt the norm. Jimmie |
10m - 40m non resonant vertical
Yes, you don't want to get much longer than 5/8WL on
10m and you don't want to get much shorter than 3/16WL on 40m. Cecil: I compared your simulation against what I found and the results are simular. I'll use your tips about the height and simulate some more lenghts based on the materials I can get. Unless you already have the materials I suggest you build with ten foot lengths of chain link top rail. The last time I priced it at the home improvement store it was $11 per section. John: I had to use google to figure out the "chain link top rail" but it is clear to me now. I'll check the DIY stores over here on garden and fences stuff. Experimenting with a too long antenna on 10M can be fun. I did a 1.25 wl antenna and got some interesting results during band openings. Jimmie: My thoughts too, get good 10m performance and as a bonus the other bands Thanks to all for your helpful reply's. 73's Fred got and "Cecil Moore" wrote in message ... Fred PA0FVH wrote: Is 5/8WL on 10meters a good height or 8 meter (22')? What I want is a low take off angle on 20 and 30 meters with high efficiency and an impedance which my remote ATU can handle. 22 feet is a good compromise length. At my previous QTH I used a 22' monopole with the feedpoint elevated at 22' with four 22' radials sloping down at 45 degrees (also used as guy wires) and fed with an SG-230. It worked like a charm for transmitting - noisy on receive. Here's some information from simulations: 22' Monopole with 22' elevated sloping radials: Band: Gain: Take Off Angle: Feedpoint: ~Tuner Loss 40m: 0.53 dBi: 22 deg: 24-j229 ohms: 0.9 dB 30m: 0.94 dBi: 19 deg: 46-j31 ohms: 0.2 dB 20m: 1.47 dBi: 16 deg: 128+j233 ohms: 0.1 dB 17m: 1.91 dBi: 14 deg: 556+j583 ohms: 0.2 dB 15m: 2.47 dBi: 12 deg: 1315-j372 ohms: 0.3 dB 12m: 3.40 dBi: 13 deg: 373-j560 ohms: 0.3 dB 10m: 4.21 dBi: 11 deg: 885-j290 ohms: 0.2 dB -- 73, Cecil http://www.w5dxp.com |
10m - 40m non resonant vertical
Fred,
You may find my article "An unloaded elevated vertical as a multi-band HF antenna" a source of some ideas. The article is at http://www.vk1od.net/multibandunload...ical/13mEV.htm .. Owen |
10m - 40m non resonant vertical
Owen,
Your article was of good help. I will start with half the size (6.5m) for 10-40m. Thanks, Fred |
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