Dave, I'm late to the party, but this, along with AD #100, is as nice an introduction to antenna theory as can be found anywhere on RUclips. Many thanks.
"No ham is ever satisfied with his or her antenna." Brilliantly true! By the way... good antenna and poor radio beats a poor antenna and excellent radio every single time.
Initial built for new hams usually results in dissapointment. Its only after learning precicely how they interact with environment and taking advantage of those influences do they learn to optimize them.
Good information, and useful analyses of the different heights of a dipole. It is a great time to be alive! with all these cool antenna modeling programs, combined with antenna analyzers, and readily available shared knowledge. Congrats on the new sponsor, and your contribution to the ham radio hobby.
Great Job Dave....I am an attorney and enjoyed your "nonlegal" arguments in regards to Chinese hand helds like the Baofang et al. Glad you are feeling better. 73 de Ed WA2BOX
Thank you Mr Casper. Your screen at 11:15 helps greatly. My antenna is in a very small back garden and is half over ground and half over a flat roof garage. I can compare how the two halves are affected from your diagrams.
Excellent and very helpful, Dave! Much appreciated. I have a HF transceiver and recently put up a 10-meter dipole. I am not yet licensed (studying) so I just listen, but I checked the SWR and it is 1:1 around 27.300. The antenna isn’t high; it’s six feet off the ground along the top of a wooden fence. Can you give me some insight into how the ground is affecting the SWR?? This is an amazingly fascinating hobby!
I know im asking the wrong place but does anyone know a trick to get back into an Instagram account..? I stupidly lost the password. I would love any tips you can offer me!
@Lawson Karsyn Thanks so much for your reply. I got to the site thru google and I'm in the hacking process atm. Takes a while so I will reply here later with my results.
The angles of all those lobes also affects the skip pattern - high lobes will skip back to earth closer to the station, lower lobes go farther before returning to earth. If you've been getting odd contact patterns, try changing the antenna height.
Ty sir. New to ham radio. About to get my technician license. I feel like I have a better understanding of how dipoles work now. Cant wait to set up my retevis 25W rt95 and start simplexing with my dad a mile away. I plan on building a dipole for it and although I feel like I understand how to make it I had no clue how they work. I think I caught the bug 😅
I made a vertical dipole for someone that has a 12 meter and 10 meter amateur radio and a CB radio. It is only half a meter off the ground. The standing wave ratio is okay so I left it like that. I was told it works okay on band openings. He has talked long distance on his three bands. However, I have heard say when the band is open around that frequency location, propagation really can not be stopped from going far. When it is closed, a thousand watts can not give you propagation. I am speaking from what someone has told me. I am not aware of this first hand. I just made the vertical dipole. Maybe I will tell him to bring it up to 5.2 meters off the ground after seeing this video. I do not see him often.
Very good video Dave. I, and many other hams, would like to have their antennas at the optimal height for the band the antenna is cut. I would to be rich too but neither of those "likes" are a reality. Where I currently live I am fortunate to have many trees towering at 50 to more than 50 feet above ground. With a sling shot or pneumatic launcher I will be able to get some of my antennas up near 50 feet but I problem I worry about is at that height the mount points are not rigid. When the wind blows at 25 mph or greater the tops of those trees sway back and forth violently enough that my wire antennas, even with a tension system, would likely break. It would be my luck that the antenna would break during winter with snow on the ground. Most hams do not have the room laterally or the means to put their antennas much over 30 feet vertically, so many of us have to use compromised antennas. But these compromised antennas do work. Sometimes Elmers say things to the new ham and even if they say "theoretically" or "under ideal conditions" the new ham has selective hearing takes what we have told them as fact. I like how you emphasized this point several times.
Dave, you have explained all the practical options of a dipole antenna positioning. Thank you for that, very informative data. I need your advice about what would happen if I were to deploy a dipole in an oblique direction to the ground. Say, at one end at 20 feet and the other at 15 feet for a 20 meter band. The reason is that I have property/geographic difficulties and the best I can do is go with a oblique dipole. Thanks in advance for all the help and advice you give us.
Good video and explaination. I am erecting a 20 meter dipole, oriented vertically. It really does not need a tall antenna, and I am hoping it will be less subject to null areas than it was when I had it strung up horizontally.
You realize you will need a fiberglass mast approximately 75 feet tall to keep the lower end out of reach. While current is highest at the center, voltage is highest at the ends.
We have a recent FCC change regarding antenna heights. No longer 200’ away from public use airports, now it’s only 50’! Half wave height of a 40m, 66’, I guess may now involve paperwork notification at a minimum or perhaps an approval process with the FAA and FCC?? Doesn’t sound good. Still though, I’m left wondering how to safely get 1 (in the case of an inverted V) or 2 support points 66’ up so as to then string the dipole.
The short answer could be... depends on what radiation pattern you want. Straight up for NVIS.... a quaterwave. Low Angle (about 30 degrees).... a halfwave. Expect the feed point impedance to change between these. Due to interaction with the ground.
Great informative video, thanks. I have a centre fed dipole that i use on 11m and was wondering if it would work if placed along the roofline of my house, around 20 feet up, on a corner. The legs would be at 90° and feed cable coming straight down unto the shack. If it is directional, i have 4 options (placed on any of the 4 corners of the house) to suite the desired aim for dx. Thanks again.
Over the last couple of years I have been watching and learning from your videos, especially those about antennas. But I am not a ham, and don't want to be one. Still you are a good teacher and I have learned a lot, with the object being to apply it to what I am interested in, radio controlled planes and drones. I found your diagrams of radiation patterns of a dipole at various distances above the ground to be tantalizingly close to what I want to know : what would the radiation pattern be for 900 mhz with a dipole atop my roof (about 20 ft above ground). Any chance you could plug these numbers into your antenna modeller ?
If you get your tech license, you can use the ham bands for your radio control. There's already a fair number of 6m control equipment, plus you can use more power. Regarding the 900 mHz antenna, the pattern is greatly affected by the surroundings.
Hi Dave and thank you for this information. I am a new ham and I just got my General Class ticket and I am learning as much as I can about what my antenna options are considering my location I don't have many tall trees and the ones I have are all on one side of the property. I have limited options for mounting a dipole to say the least. I want to use a multi-band dipole that covers from 160 to 10 meters if I can. I have found an end fed dipole that I am interested in that is 98 feet in length that I can make work in my space. I too use the top rail sections for masts and I presently have one that is two sections high at 21 feet in use. I could set another one to use for the dipole if that will work. I know that there are other considerations here but I just want your opinion on the feasibility of this setup. I would greatly appreciate your help. Thanks and 73
Congrats on your upgrade to General! You won't find an antenna that works well 160 to 10. You might start with an off-center fed dipole that works on at least 80, 40, and 20. You can build these yourself--there are plenty of plans on the Internet.
For DX, I would always go significantly higher than a half-wave.... Look how much better the low-angle radiation is on Dave's plots, at, say 1 wavelength height. I believe that most DX signals arrive at about 7 degrees elevation, but often lower.
Well I KNOW a 2 element Qud work's WELL at 36' above most ground's .I had most of my ANT'S. Beams ,ground plain's at 72' on 11 Meters. Work VERY WELL even ground waves with 15 W radios on SSB. But coax length and grounding and a fine tuned ssb radio station is key injoy 🤔
Yes on 20m you don't want power going straight up (and just heating the moon) but on 40 for nvis you want straight up power. For a 2 element Yagi you normally have the reflector 0.15 wavelength back (ie 6m on 40m)... If your 40m dipole is low at just 20' then with the ground acting as your reflector you effectively have a 2 element yagi pointing straight up so if you want local rag chewing on 40 then just 20' may be your optimum height.
How far should a dipole antenna be away from metal objects? I was thinking about installing a ZS6BKW antenna in an inverted "V" configuration and I have a metal building that one leg of the antenna would be running parallel with and I was curious if the building might interfere with receiving and transmitting. The building would be about 10-15 away.
Where the current is highest in a dipole is where it's going to radiate the most. That means, get the center high and if the ends are lower, they don't need to be high because the current is at a minimum at the ends.
In the UHF bands I'll stick to getting an antenna as high as possible. Putting an antenna at a wavelength above ground could electrocute a passing cat.
NPC #52700000389 ask us :) and watch Dave's videos! What do you want to do? Best thing might be to hit a repeater and look for an Elmer (another ham radio Operator that knows and teaches you directly). So, what Radio do you have? And is there repeaters in your area? No idea about that? Check the App "Repeater book" and or APRS.fi for your area. Don't hesitate to on me or comment here is there is questions. 73 DJ6KR
I too passed my tech exam three months ago, finally purchased my first HT but lack the operational skills to have a QSO. I had thought it would have been really practical to include an operational section as part of the class even if it’s not on the exam. For my part I joined a club and am volunteering for club activities and watching excellent videos such as these to continue my education. I believe you will find that there are operators who will stop and explain what they’re doing - but you have to ask. So continue to be both patient and curious and don’t be afraid to jump in on the radio. 73
Unless you are using a chain or cable driven elevator you will not get much range. Also there is stability issues you must factor into load equation. Linear actuators are more stable but very limited in range.
I have an Icom MN-100 dipole antenna and i plan to make it as inverted V and put the antenna up on a 18 meter mast with the angle around 90° - 120° between both wires, the question is, is 18 meter high enough to make the antenna works efficiently ? Thanks - YG1BGK
An exceptionally well done video, Dave, thank you. On a related issue, there are many of us in rural areas that use septic systems. Are you aware of any information related to using verticals (or even other antenna systems) in conjunction with leach fields?
How many feet is the wavelength I can’t seem to find anyone stating what that is without giving a long winded explanation, it’s useful but not the direct answer I’m actually looking for and that how many feet is the actual wavelength I can’t get a straight answer from the internet no matter where I look
You would need to use Maxwell's equations to derive that, a formidable job. Better to use something like 4nec2 that models this using the NEC - numerical electromagnetic code.
Dave, Can you please explain why a transmission cable's impedance does not vary with frequency? How does it stay at 50 ohms? I though reactance was inverse to frequency?
The cable impedance is a characteristic of the cable itself. It is the ratio between the voltage and the current, and doesn't vary (much) with frequency. The cable has distributed resistance (the wire) and distributed reactance (capacitance and inductance) that all keeps the impedance uniform. The impedance of a cable can be calculated from the outer diameter of the center wire and the inner diameter of the sheath. The formula can be found online or in the ARRL manuals.
I understand the best height is half wave length for dipole's. But for CB (11 meters) and 10 meters is that the same recommendation. The usual thing on those bands is "height is might". But obviously for verticals. But is height best for 11 & 10 meters? I am still learning. I am a foundation licence (an F call). Thankyou. 73 VK3FION. (By the way, I am an "ogie")
Thanks for being an Oggie! On 10 and 11 meters, it's hard not to mount the antennas a couple wavelengths high! The elevation pattern will be split a bit, but height is usually considered a good thing.
They work either way performance may vary due to the recoivers polarity but generally not much. Look up building a vertical ground plane. They are easy to build, easy to tune. And perform very good. I believe Dave has a video on them.
Hi David, for international DX shouldn't I get my 10m dipole up to about .65 lambda? I use a center-fed 1.25 lambda dipole driven by coax through a 4:1 by Balun Designs at the feed point.
@@davecasler Will it lose power in the lower lobes or gain overall including in the upper lobe? I was under the impression the lower lobes gained a dB or so overall.
Three story is the living space measurement attic height is extra. Average room height floor to floor is usually 8 feet or more. So 3 story is approx 24 feet plus about 6 feet average attic height If you walk up steps into the building include that height as well. So on average without stairs and ground level you are nearly 30 feet Damn close to 1/2 wavelength so you wont notice the very minute difference.
In case of a vertical dipool : Half wavelenght to ground, is this clearance between ground and end of the antenna or is this from ground to mid antenna (feed point). PS: @27Mhz
1/4 wavelength or 8 feet to put it out of anyones reach, also for optimum performance and easier matchingyou want your feed line to run perpendicular at least 1/4 wavelength as well
I really liked this video. Could you use EZNEC to model the 30’ wire vertical and a counterpoise. This is what I use for SOTA work, and I would like to see the optimum way to erect this antenna. Thanks again.
so a half wavelength height "rule" was just for 20 meter band or applies to all bands?.......meaning the best height for a dipole antenna for the 2 Meter band is 3.3 feet? and a 70 CM band at 1.2 feet?.....seems pretty low and if my assumption is right (too low), what height should I place a dipole for 2 M and 70 CM bands? (I'm studying for the Technician exam and would like to put up an antenna for these two bands)
Yes, the half wavelength height is optimum for all antennas. For VHF antennas up high, there will be so much lensing that it will appear as if it’s one lobe. My UHF 10-element beam is only about 6 feet off the ground because that was a convenient height and is plenty high for the beam to do its work.
Very interesting and informative video. I currently have a ZS6BKW set up as an inverted V with the center at about 35 feet. The nagging question I've been considering lately is whether it matters that the two arms of my V, instead of being straight from the peak to their ends, are a bit saggy. I'd like to know whether it's worth getting the ladder out and pulling them tighter before the snow flies. 73 de NN8G
@@popefelix Wirh inverted v, s, the angle between the two wires of the antenna makes a lot of diffetence, altering the resonant frequency, the inpedence and the SWR. I have just spent a day, at 3deg c, playing with one! Its getting better, but a bit like playing 3D chess! M0iiZ PS. The ZD6BKW is a great antenna. Much better than a G5RV. Makes the transceivers ATU have a much quieter life!
Hello OM! Great video, I've been a fan for a while. When you saying "Height at .5 wl above ground, are you saying the entire dipole hung as a flattop where ALL of the elements are .5 wl above ground OR the where the Apex of a dipole hung in an inverted V is .5 wl above ground?
You cant beat a well made dipole for its simplicity. Home brew 20 meter dipole, well tuned, 32 feet in the air, 5 watt ssb, no amp. And proudly farthest qso's from pennsylvania USA to western Russia, France,& Scotland
Dave. I have a 40/20 meter fan doublet up at 95 feet. It works excellent into vk and zl in the early morning on both 40 and 20. This is with 100 watts so I have to disagree. Height is might. My zero five ground plane with 6 long above ground radials and 80 in ground radials is 6 dbd down on 40 and about 8 dbd down on 20 in the two direction my dipoles are oriented. The 95' doublet smokes the vertical 75% of the time. I hope these big trees grow higher. Would love to be at 120 feet one day. One more thing. The dipole up over one wavelength does not waste power going nowhere. Look again at your charts. There is a few higher angles which are good for regional contacts. So the point is I am surprised you recommend a half wave high when a full wavelength will always give you much better bidirectional gain.
If you read the various Antenna Handbooks, you wont need to model anything. Just throwing up an antenna in your space will garner contacts. I have made contacts at 12 feet off the ground, 20 feet off the ground and 32 feet off the ground. You are giving the impression that antennas are complicated with this modeling methodology, when they are not. This is why many hams choose to not experiment because of those darn charts and radiation patterns. Can you do one up for my antenna mmade from crutches?
Hams take different approaches to technology, from the "throw something up and make it work" to the carefully-engineered. Though I tend to be in the former category, I am an engineer and do like to know how things work, hence the analytics.
None of that really matters. There are a few types of antennas that are never ever going to radiate, those are the one drawn on paper or in software, any antenna not built yet, the antenna in its' bag under the bench, the antenna googled on your screen but never got around to making, and the ones debated over on the internet. The ONLY antenna that is going to radiate at all is one up in the air with a working transceiver connected with the mic button pressed. Moral of the story is self-evident - get off the internet and go build something.
![I.N "HALLUCINATION" | [Stray Kids : SKZ-PLAYER]](http://i.ytimg.com/vi/n5B5q1Hwt_U/mqdefault.jpg)
Dave, I'm late to the party, but this, along with AD #100, is as nice an introduction to antenna theory as can be found anywhere on RUclips. Many thanks.
"No ham is ever satisfied with his or her antenna." Brilliantly true! By the way... good antenna and poor radio beats a poor antenna and excellent radio every single time.
Initial built for new hams usually results in dissapointment.
Its only after learning precicely how they interact with environment and taking advantage of those influences do they learn to optimize them.
Good information, and useful analyses of the different heights of a dipole. It is a great time to be alive! with all these cool antenna modeling programs, combined with antenna analyzers, and readily available shared knowledge. Congrats on the new sponsor, and your contribution to the ham radio hobby.
Great Job Dave....I am an attorney and enjoyed your "nonlegal" arguments in regards to Chinese hand helds like the Baofang et al. Glad you are feeling better. 73 de Ed WA2BOX
Thank you Mr Casper. Your screen at 11:15 helps greatly. My antenna is in a very small back garden and is half over ground and half over a flat roof garage. I can compare how the two halves are affected from your diagrams.
Excellent and very helpful, Dave! Much appreciated. I have a HF transceiver and recently put up a 10-meter dipole. I am not yet licensed (studying) so I just listen, but I checked the SWR and it is 1:1 around 27.300. The antenna isn’t high; it’s six feet off the ground along the top of a wooden fence. Can you give me some insight into how the ground is affecting the SWR?? This is an amazingly fascinating hobby!
This is one of your best videos, Dave. Thank you so much. Happy to share this!
I know im asking the wrong place but does anyone know a trick to get back into an Instagram account..?
I stupidly lost the password. I would love any tips you can offer me!
@Orlando Augustine Instablaster =)
@Lawson Karsyn Thanks so much for your reply. I got to the site thru google and I'm in the hacking process atm.
Takes a while so I will reply here later with my results.
@Lawson Karsyn It did the trick and I finally got access to my account again. I am so happy:D
Thank you so much, you saved my account !
@Orlando Augustine you are welcome =)
The angles of all those lobes also affects the skip pattern - high lobes will skip back to earth closer to the station, lower lobes go farther before returning to earth. If you've been getting odd contact patterns, try changing the antenna height.
Ty sir. New to ham radio. About to get my technician license. I feel like I have a better understanding of how dipoles work now. Cant wait to set up my retevis 25W rt95 and start simplexing with my dad a mile away. I plan on building a dipole for it and although I feel like I understand how to make it I had no clue how they work. I think I caught the bug 😅
I made a vertical dipole for someone that has a 12 meter and 10 meter amateur radio and a CB radio. It is only half a meter off the ground. The standing wave ratio is okay so I left it like that. I was told it works okay on band openings. He has talked long distance on his three bands. However, I have heard say when the band is open around that frequency location, propagation really can not be stopped from going far. When it is closed, a thousand watts can not give you propagation. I am speaking from what someone has told me. I am not aware of this first hand. I just made the vertical dipole. Maybe I will tell him to bring it up to 5.2 meters off the ground after seeing this video. I do not see him often.
Very good video Dave. I, and many other hams, would like to have their antennas at the optimal height for the band the antenna is cut. I would to be rich too but neither of those "likes" are a reality. Where I currently live I am fortunate to have many trees towering at 50 to more than 50 feet above ground. With a sling shot or pneumatic launcher I will be able to get some of my antennas up near 50 feet but I problem I worry about is at that height the mount points are not rigid. When the wind blows at 25 mph or greater the tops of those trees sway back and forth violently enough that my wire antennas, even with a tension system, would likely break. It would be my luck that the antenna would break during winter with snow on the ground. Most hams do not have the room laterally or the means to put their antennas much over 30 feet vertically, so many of us have to use compromised antennas. But these compromised antennas do work. Sometimes Elmers say things to the new ham and even if they say "theoretically" or "under ideal conditions" the new ham has selective hearing takes what we have told them as fact. I like how you emphasized this point several times.
Yes, trees don't stay still. There are many approaches to keeping the antennas from breaking, but Mother Nature seems smarter than us all!
Wonderful David - Thanks for this and 73!
Dave, you have explained all the practical options of a dipole antenna positioning. Thank you for that, very informative data. I need your advice about what would happen if I were to deploy a dipole in an oblique direction to the ground. Say, at one end at 20 feet and the other at 15 feet for a 20 meter band. The reason is that I have property/geographic difficulties and the best I can do is go with a oblique dipole. Thanks in advance for all the help and advice you give us.
That is a sloper dipole it will work fine maybe a bit more directional than a horizontal due to ground reflection.
Great for tropo ducting.
Thanks Dave. That was very helpful. 73
Good video and explaination. I am erecting a 20 meter dipole, oriented vertically. It really does not need a tall antenna, and I am hoping it will be less subject to null areas than it was when I had it strung up horizontally.
Should give you a nice uniform azimuth pattern.
whats the amazon link to the water bottle on your desk
Great video .thanks for all the information
Great video Dave...excellent explanation!
I’ve been thinking about making a 20m vertical dipole. I want a vertical but don’t want to deal with the hassle of ground radicals.
You realize you will need a fiberglass mast approximately 75 feet tall to keep the lower end out of reach.
While current is highest at the center, voltage is highest at the ends.
We have a recent FCC change regarding antenna heights. No longer 200’ away from public use airports, now it’s only 50’! Half wave height of a 40m, 66’, I guess may now involve paperwork notification at a minimum or perhaps an approval process with the FAA and FCC?? Doesn’t sound good. Still though, I’m left wondering how to safely get 1 (in the case of an inverted V) or 2 support points 66’ up so as to then string the dipole.
This is the first I've heard of this. Please provide a URL so I can read further.
Mine is on a Slope. One end is 100 high and the other one around 40 to 50 high also..Works well
The short answer could be... depends on what radiation pattern you want.
Straight up for NVIS.... a quaterwave.
Low Angle (about 30 degrees).... a halfwave.
Expect the feed point impedance to change between these. Due to interaction with the ground.
Great informative video, thanks. I have a centre fed dipole that i use on 11m and was wondering if it would work if placed along the roofline of my house, around 20 feet up, on a corner. The legs would be at 90° and feed cable coming straight down unto the shack. If it is directional, i have 4 options (placed on any of the 4 corners of the house) to suite the desired aim for dx. Thanks again.
Great video and impressive knowledge. Thank you!
Love your videos. How high should an EFHW antenna be? My will be horizontal. Not sloping, inverted, etc.
EFHW is very the same in terms of radiation patterns as centerfed dipole.
Over the last couple of years I have been watching and learning from your videos, especially those about antennas. But I am not a ham, and don't want to be one. Still you are a good teacher and I have learned a lot, with the object being to apply it to what I am interested in, radio controlled planes and drones.
I found your diagrams of radiation patterns of a dipole at various distances above the ground to be tantalizingly close to what I want to know : what would the radiation pattern be for 900 mhz with a dipole atop my roof (about 20 ft above ground). Any chance you could plug these numbers into your antenna modeller ?
If you get your tech license, you can use the ham bands for your radio control. There's already a fair number of 6m control equipment, plus you can use more power. Regarding the 900 mHz antenna, the pattern is greatly affected by the surroundings.
Thanks, but that is vague enough to not be helpful.
I can’t get a straight answer of how many feet is a half a wave length
Hi Dave and thank you for this information. I am a new ham and I just got my General Class ticket and I am learning as much as I can about what my antenna options are considering my location I don't have many tall trees and the ones I have are all on one side of the property. I have limited options for mounting a dipole to say the least. I want to use a multi-band dipole that covers from 160 to 10 meters if I can. I have found an end fed dipole that I am interested in that is 98 feet in length that I can make work in my space. I too use the top rail sections for masts and I presently have one that is two sections high at 21 feet in use. I could set another one to use for the dipole if that will work. I know that there are other considerations here but I just want your opinion on the feasibility of this setup. I would greatly appreciate your help. Thanks and 73
Congrats on your upgrade to General! You won't find an antenna that works well 160 to 10. You might start with an off-center fed dipole that works on at least 80, 40, and 20. You can build these yourself--there are plenty of plans on the Internet.
For DX, I would always go significantly higher than a half-wave.... Look how much better the low-angle radiation is on Dave's plots, at, say 1 wavelength height. I believe that most DX signals arrive at about 7 degrees elevation, but often lower.
Well I KNOW a 2 element Qud work's WELL at 36' above most ground's .I had most of my ANT'S. Beams ,ground plain's at 72' on 11 Meters. Work VERY WELL even ground waves with 15 W radios on SSB. But coax length and grounding and a fine tuned ssb radio station is key injoy 🤔
Yes on 20m you don't want power going straight up (and just heating the moon) but on 40 for nvis you want straight up power. For a 2 element Yagi you normally have the reflector 0.15 wavelength back (ie 6m on 40m)... If your 40m dipole is low at just 20' then with the ground acting as your reflector you effectively have a 2 element yagi pointing straight up so if you want local rag chewing on 40 then just 20' may be your optimum height.
How far should a dipole antenna be away from metal objects? I was thinking about installing a ZS6BKW antenna in an inverted "V" configuration and I have a metal building that one leg of the antenna would be running parallel with and I was curious if the building might interfere with receiving and transmitting. The building would be about 10-15 away.
super informative, thank you
Got 11 meter dipole would 25 foot from ground be ok
Does this height data also apply to directed dipoles with a reflector like the ones that Bob Heil uses?
Yes, although the pattern is quite different. A dipole with a reflector at the same height at the dipole is a simple form of a Yagi.
As always, thanks Dave - K2PTL
Great video Dave! Thanks.
Curious, how does a dipole in an inverted v configuration at various elevations?
Pretty much the same result.
Where the current is highest in a dipole is where it's going to radiate the most. That means, get the center high and if the ends are lower, they don't need to be high because the current is at a minimum at the ends.
Well explained thanks
How does the hex change as it goes from 7ft to say 50?
Haven't looked. It'll be something similar. Thanks for the topic suggestion.
My Father was a quad and dipole junky, you could throw a block of cheese in the air and it would come down in slices!!!..Wires everywhere!🤣👍
Excellent video. Thank you, Dave.
73
Dave
WA7AXT
What is the best height for an 11 meter dipole and should it be mounted horizontal or vertical for dx. Thanks.
In the UHF bands I'll stick to getting an antenna as high as possible. Putting an antenna at a wavelength above ground could electrocute a passing cat.
I passed tech exam three month ago but have no idea how to operate a little yaesu radio. How can I learn practical skills?
NPC #52700000389 ask us :) and watch Dave's videos! What do you want to do? Best thing might be to hit a repeater and look for an Elmer (another ham radio Operator that knows and teaches you directly). So, what Radio do you have? And is there repeaters in your area? No idea about that? Check the App "Repeater book" and or APRS.fi for your area. Don't hesitate to on me or comment here is there is questions. 73 DJ6KR
Is there a club that meets near you ? Otherwise never under estimate the educational videos on RUclips.
@@KiwiCatherineJemma Will look for a club. Tried videos, God bless people who put them up. But need more. Thank you
I too passed my tech exam three months ago, finally purchased my first HT but lack the operational skills to have a QSO. I had thought it would have been really practical to include an operational section as part of the class even if it’s not on the exam. For my part I joined a club and am volunteering for club activities and watching excellent videos such as these to continue my education. I believe you will find that there are operators who will stop and explain what they’re doing - but you have to ask. So continue to be both patient and curious and don’t be afraid to jump in on the radio. 73
Are there motorized systems to raise and lower a dipole in a similar fashion as a yagi is rotated?
Unless you are using a chain or cable driven elevator you will not get much range.
Also there is stability issues you must factor into load equation.
Linear actuators are more stable but very limited in range.
I have an Icom MN-100 dipole antenna and i plan to make it as inverted V and put the antenna up on a 18 meter mast with the angle around 90° - 120° between both wires, the question is, is 18 meter high enough to make the antenna works efficiently ? Thanks - YG1BGK
Is this half wavelength high rule of thumb also correct for beam antennas?
Yes, in general.
Great video. Thank you.
Also keep in mind that the higher up your antenna off the ground, the larger its line-of-sight area will be.
73 VE7NDE
What is the best antennas for ads 200 police scanner and should it be grounded
SDS 200
An exceptionally well done video, Dave, thank you. On a related issue, there are many of us in rural areas that use septic systems. Are you aware of any information related to using verticals (or even other antenna systems) in conjunction with leach fields?
No, but it may help. I also have a leach field, but my antennas are not directly over it.
Gee...I wondered where those crappy signal's came from ?
¯\_💩_/¯
Seventy Turds !
How many feet is the wavelength I can’t seem to find anyone stating what that is without giving a long winded explanation, it’s useful but not the direct answer I’m actually looking for and that how many feet is the actual wavelength I can’t get a straight answer from the internet no matter where I look
Thanks Dave, 73 de YC0DMS..
what will be the equation for far field when dipole antenna is at arbitrary location .??
You would need to use Maxwell's equations to derive that, a formidable job. Better to use something like 4nec2 that models this using the NEC - numerical electromagnetic code.
Dave, Can you please explain why a transmission cable's impedance does not vary with frequency? How does it stay at 50 ohms? I though reactance was inverse to frequency?
The cable impedance is a characteristic of the cable itself. It is the ratio between the voltage and the current, and doesn't vary (much) with frequency. The cable has distributed resistance (the wire) and distributed reactance (capacitance and inductance) that all keeps the impedance uniform. The impedance of a cable can be calculated from the outer diameter of the center wire and the inner diameter of the sheath. The formula can be found online or in the ARRL manuals.
Given this information, do you think it better to get a 2 meter dipole high as possible (conventional wisdom) or to put it a half wavelength up?
Probably up a ways. For FM work remember to use vertical polarization.
I understand the best height is half wave length for dipole's. But for CB (11 meters) and 10 meters is that the same recommendation. The usual thing on those bands is "height is might". But obviously for verticals. But is height best for 11 & 10 meters? I am still learning. I am a foundation licence (an F call). Thankyou. 73 VK3FION. (By the way, I am an "ogie")
Thanks for being an Oggie! On 10 and 11 meters, it's hard not to mount the antennas a couple wavelengths high! The elevation pattern will be split a bit, but height is usually considered a good thing.
Thanks mate.
32 feet or high for 11meters, depending on your layout indoor or outdoor!! It's alot of Fun!! Thanks for reading my comment!!
Wouldn't an aluminum toroid make a good antenna?
What about a vertical dipole UHF/VHF?
They work either way performance may vary due to the recoivers polarity but generally not much.
Look up building a vertical ground plane. They are easy to build, easy to tune. And perform very good.
I believe Dave has a video on them.
Hi David, for international DX shouldn't I get my 10m dipole up to about .65 lambda? I use a center-fed 1.25 lambda dipole driven by coax through a 4:1 by Balun Designs at the feed point.
The optimum height is 0.5 lambda. At 0.65 lambda the pattern will be a bit lower but you will start to lose power to a higher lobe.
@@davecasler Will it lose power in the lower lobes or gain overall including in the upper lobe?
I was under the impression the lower lobes gained a dB or so overall.
If your dipole is going in the attic (thank you HOA) does the fact that its 3 stories high still count in "how high the dipole is?" Thanks, Dave N9DMS
Three story is the living space measurement attic height is extra.
Average room height floor to floor is usually 8 feet or more.
So 3 story is approx 24 feet plus about 6 feet average attic height
If you walk up steps into the building include that height as well.
So on average without stairs and ground level you are nearly 30 feet
Damn close to 1/2 wavelength so you wont notice the very minute difference.
Comment was based on 20 meters.
In case of a vertical dipool : Half wavelenght to ground, is this clearance between ground and end of the antenna or is this from ground to mid antenna (feed point). PS: @27Mhz
1/4 wavelength or 8 feet to put it out of anyones reach, also for optimum performance and easier matchingyou want your feed line to run perpendicular at least 1/4 wavelength as well
I really liked this video. Could you use EZNEC to model the 30’ wire vertical and a counterpoise. This is what I use for SOTA work, and I would like to see the optimum way to erect this antenna. Thanks again.
Thanks for the topic suggestion.
so a half wavelength height "rule" was just for 20 meter band or applies to all bands?.......meaning the best height for a dipole antenna for the 2 Meter band is 3.3 feet? and a 70 CM band at 1.2 feet?.....seems pretty low and if my assumption is right (too low), what height should I place a dipole for 2 M and 70 CM bands? (I'm studying for the Technician exam and would like to put up an antenna for these two bands)
Yes, the half wavelength height is optimum for all antennas. For VHF antennas up high, there will be so much lensing that it will appear as if it’s one lobe. My UHF 10-element beam is only about 6 feet off the ground because that was a convenient height and is plenty high for the beam to do its work.
Take that lower lobe and add power the DX solution
Nice one Dave de G6JMX
Very interesting and informative video. I currently have a ZS6BKW set up as an inverted V with the center at about 35 feet. The nagging question I've been considering lately is whether it matters that the two arms of my V, instead of being straight from the peak to their ends, are a bit saggy. I'd like to know whether it's worth getting the ladder out and pulling them tighter before the snow flies. 73 de NN8G
It's always worth it! Even if it doesn't necessarily improve performance, you can have fun fiddling with the thing outside.
Slightly saggy vs so tight they break in the wind. It's a balance.
@@popefelix Wirh inverted v, s, the angle between the two wires of the antenna makes a lot of diffetence, altering the resonant frequency, the inpedence and the SWR. I have just spent a day, at 3deg c, playing with one! Its getting better, but a bit like playing 3D chess! M0iiZ PS. The ZD6BKW is a great antenna. Much better than a G5RV. Makes the transceivers ATU have a much quieter life!
ECNET and MMANA are almost the same but I think this is just my thought is the MMANA is a bit better than ECNET
Thank you. I am more confused now, but I did get an answer. LOL
Hello OM! Great video, I've been a fan for a while. When you saying "Height at .5 wl above ground, are you saying the entire dipole hung as a flattop where ALL of the elements are .5 wl above ground OR the where the Apex of a dipole hung in an inverted V is .5 wl above ground?
flat dipole
Dave, Your my go to man and very much appreciated. K5upg. roger.
I’m so confused. I just want the simplest antenna that’ll will let me transmit and receive on 20m
You cant beat a well made dipole for its simplicity.
Home brew 20 meter dipole, well tuned, 32 feet in the air, 5 watt ssb, no amp. And proudly farthest qso's from pennsylvania USA to western Russia, France,& Scotland
Dave. I have a 40/20 meter fan doublet up at 95 feet. It works excellent into vk and zl in the early morning on both 40 and 20. This is with 100 watts so I have to disagree. Height is might. My zero five ground plane with 6 long above ground radials and 80 in ground radials is 6 dbd down on 40 and about 8 dbd down on 20 in the two direction my dipoles are oriented. The 95' doublet smokes the vertical 75% of the time. I hope these big trees grow higher. Would love to be at 120 feet one day. One more thing. The dipole up over one wavelength does not waste power going nowhere. Look again at your charts. There is a few higher angles which are good for regional contacts. So the point is I am surprised you recommend a half wave high when a full wavelength will always give you much better bidirectional gain.
If you read the various Antenna Handbooks, you wont need to model anything. Just throwing up an antenna in your space will garner contacts. I have made contacts at 12 feet off the ground, 20 feet off the ground and 32 feet off the ground. You are giving the impression that antennas are complicated with this modeling methodology, when they are not. This is why many hams choose to not experiment because of those darn charts and radiation patterns. Can you do one up for my antenna mmade from crutches?
Hams take different approaches to technology, from the "throw something up and make it work" to the carefully-engineered. Though I tend to be in the former category, I am an engineer and do like to know how things work, hence the analytics.
Excellent discussion. New sub. Karl AF5LQ
HOW HIGH SHOULD A GROUND PLANE BE ? IM GUESSING 1 WAVE LENGTH ABOVE THE GROUND.
If it does not fall down it is not high enough......
You lost me when you said space station.
None of that really matters. There are a few types of antennas that are never ever going to radiate, those are the one drawn on paper or in software, any antenna not built yet, the antenna in its' bag under the bench, the antenna googled on your screen but never got around to making, and the ones debated over on the internet. The ONLY antenna that is going to radiate at all is one up in the air with a working transceiver connected with the mic button pressed. Moral of the story is self-evident - get off the internet and go build something.
I think that's the point.
Too much superfluous content. He started with a question and went to another world.
You lost me at isotropic antenna!
Isotropic antenna is a theoretical antenna in space and a comparative mathematic representation
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When you set the dipole low enough to get the maximum radiation at around 5 degrees above the horizon
Another totally subjective formula
I disagree. I laid out all the results and showed why I drew the conclusions I drew.