9 pages and full circle , " HF propagation is the worst I have ever seen it, in 52 years of hamming. It must be terribly frustrating for a 'newbie' wanting to work the world with modest resources. And that is where the benefit of knowledge in antennas/physics plays,to wit: HOW DO I GET A BETTER ANTENNA?--a foundation of amateur radio--goes a long way towards improvement of the station and the opportunities for enjoying contacts from afar. " 73 Chip W1YW Learn enough to set up a station and get the most out of it - it is necessary to learn somethings . Just because there are large numbers of those that can operate a box-cutter and have money to buy the box , does not change the definition of being a ham radio operator - not necessarily building a radio from scratch , but at be able to build / setup / adjust your antenna to operate well , seems like a min. Understand how to use at least a SWR meter , dummy load & multimeter for the above . The opposition seems to be justified [ by ] there large numbers , that cannot use / or understand the above equipment , to help make there station work better . And also hams being helpful to others - to learn to operate .
I began building my own wire antennas in 1965 as an SWL. I'm more interested in antennas than any other aspect of amateur radio, other than radio wave propagation. I've never purchased a store bought antenna. In the past 30 years of being a ham I've designed, built and erected just about every antenna imaginable, some "out of the box" so to speak. EZNEC and an antenna analyzer are important tools for me. My favorite antenna is a 1/4 wave vertical/inverted L for 160 meters, followed by an all band off center fed doublet and then a full wave horizontal loop.
Dennis Your analysis is flawed. A beam (hex or otherwise) will have gain over a dipole. IT WILL NOT HAVE -3db (negative gain). Gain is just a measure of directivity. The 5.3dBi you quoted is also in free space just like the 2.2dBi of a dipole; you get about 3dB of gain. PLUS you get the benefit of the F/B ratio as well. You are correct that the bending does cost some efficiency, but with the bend in a hex the loss is not severe at all. Cheers James
Just because someone calls an antenna a "beam" doesn't necessarily mean that it has gain over a dipole. What is your source of information for your statement that the 5.3dbi figure is in free space? Antenna manufacturers usually publish the spec with the highest number because the uninformed customer will believe that it's a higher gain antenna. They include the ground reflection in their spec because it looks better than if they would publish the lower number spec for the antenna in free space. I don't believe that an antenna that is physically less than half a wavelength long, has less than optimum spacing between bent elements, and has several other elements for operation on other bands, is capable of 3db gain over a dipole when both antennas are at the same height above ground.
As a newbi, licensed in April of 2018, it's hard to imagine what the "good ole days" must have been like.....but, it's not been to bad IMO, having worked 96 countries so far with a modest station.....with just over a thousand dollars tied up in it......a 30 year old kenwood 450, 50 year old Hammarlund HXL-One amplifier, MFJ-998 auto tuner and OCFD in an inverted v at 35 feet......so, no, it hasn't been terribly frustrating for me......as it's the only conditions I've been exposed too.... That said, it must be terribly frustrating to those hams who've had good working conditions in the past and don't have them now. From my perspective, it's been good, and it's only going to get better. GO WITH THROTTLE UP!
Glad you enjoy it In 1991, for example, you could have used your ensemble --without the amp-- on 10m and had 24 hour propagation across the world. That would be at , say, 20 watts. The big problem was the 10m phone band was so crowded that stations would fight over a frequency, often a EU arguing with a US. I have 320 countries on 10m. Almost all of them were worked in 1989- 1992. Similar conditions were typical in 2001, and 1969, amongst others. Now 10 and 12m are generally unused in comparison, and even then 10m is very feeble during major contests. This weekend I worked 80 '10m contest' stations, In `1989 I worked 1900. In today's bad HF prop, playing and improving your antenna--and knowing how to do so and why-- makes the margin between having fun and hearing noise. 73 Chip W1YW
Well I used to teach Electrical Engineering at the college level, so I understand antenna modeling to some degree. A hex beam is a half wave, it is just folded; but the fold is really not that extreme. There is some loss of efficiency. Look at K4KIO's webpage, he specifies free space gain of 5.5dBi . Antenna manufactures generally use free space gain because height over ground and ground conductivity are generally unknown. Free Space is the common accepted baseline The definition of gain is based in directivity. If they are both radiating the same amount of power, but one is radiating into a smaller portion of the sphere, it will have better performance; can't get around that. A dipole over the ground, depending on height, can appear somewhere between bi-directional and omni-directional. I beam will have a preferred direction. This gives it more gain. I need to read the article you posted claiming a dipole can achieve 8dBi; I am not certain I buy that
The original hexbeam design is two approximately electrical half wave "w''s back to back in a Yagi/Moxon type configuration (driven and a parisitic-- either reflector or director), so the size reduction is fairly substantial. In later 'versions' by others, the upside-down umbrella mechanical supports were kept, but the elements utilized the circumference of the hex shape. Essentially they are Moxons in a hex configuration. Unfortunately, people missed the point, it would seem: ' hex beam' refers to a shrunken config using triangularly folded of elements (into a 'w'), not a mechanical support system that has six sides. The hex shaped mechanicals were designed by N1HXA to make it easy to support the 'W's... Others kept Mike's (mechanical) umbrella framework and chucked the electrical element design. That seems to be where the point was missed. We need to think about antennas as electrical devices first, and mechanical gadgets after. 73 Chip W1YW
You are spot on. The hex refers to the support structure, not the antenna itself. The folded nature cuase some loss of efficiency, but since it never fully folds back on itself, the loss is acceptable for the mechanical benefits. The other poster was concerned with the interaction of adjacent bands. I should have pointed out that of all the bands the only ones that affect each other at all, is there can be some interaction between 6m and 17m. The others are effectively invisible to one another
I inserted a link in my post #37 on this thread. Just go to w8ji.com, it appears several times in Tom's articles about antennas.
Hi Chip, can you model a half wave dipole, approximately .67 wavelength over earth, with gain in dbi, and post your result here?
I have also thought more about one of your assertions about the ground making the gain higher. Real ground always makes antenna performance worse since it absorbs some of the RF.
