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How Do I Get a Better Antenna?

Discussion in 'Amateur Radio News' started by VK6FLAB, Dec 7, 2018.

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  1. VK6FLAB

    VK6FLAB Ham Member QRZ Page

    foundations-of-amateur-radio_300.jpg
    Foundations of Amateur Radio

    How do I get a better antenna?

    Foundations of Amateur Radio

    The question that new amateurs most often ask after "What radio should I buy?" is "How do I get the best antenna?".

    In a household where you're the only antenna affected aficionado the question is likely more along the lines of: "Why do you need another antenna?".

    The answer is pretty much the same, an antenna is fit for purpose, generally only one purpose.

    Going from A to B without walking might involve a car. If it's just you, one seat is enough, if your local cricket team is coming too, you might need more seats. If the road is rough, you might need a good suspension and if it's the middle of summer in Australia, air-conditioning isn't a luxury but a necessity.

    Each of those different requirements varies depending on circumstance and need. There are plenty more variables, fuel, distance, cost, and the deeper you dig, the more choices.

    Antennas are no different.

    While cars have an element of fashion, colour, styling etc. antennas are more utilitarian, radio amateurs rarely care about the colour of their contraption, but they do care about cost, construction and performance.

    Those three variables alone would make for plenty of choice, but we've not yet talked about some other variables that come into play.

    If you're a licensed amateur, picking the frequency you want to use is obvious and a major factor in the choice of antenna, but if you're not an amateur, that's not something obvious, but you have seen it before.

    Without going into the physics of how and why, imagine all the antennas you've seen in your life. There's a TV antenna on the roof, the antenna on a transistor radio, an antenna on a car, the antenna on your Wi-Fi modem, a mobile phone antenna, satellite dishes, you might have seen antennas near train lines, on top of traffic lights, on a GPS and on a satellite phone. You might not be familiar with all of them, but enough to know that there is a huge range of different types of antennas. The more you look, the more variation you find.

    You might think that each of those different antennas was chosen at the whim of the person spending the money, but actually, each of those antennas was chosen for a specific job. Each of those antennas works on at least one frequency, sometimes more and does so taking into account its purpose. Is the antenna for sending, or receiving, or both? Is it supposed to work regardless of where it's installed, or how high off the ground it is? Does it need to take into account interference from a particular direction? Is it meant for strong or weak signals, does it need to have a defined lifespan, deal with a particular wind strength, etc. etc.

    Answering each of those questions determines the choices made to select an antenna from the infinite variety available.

    As an amateur, my licence allows me to operate in six different frequency ranges or bands. Technically that means at least six different antennas, just so I can use the frequencies I'm licensed for.

    Of course I'm only scratching the surface here, since I've already explained that antennas come in many different shapes and sizes, each with different characteristics and trade-offs.

    So next time you wonder why so many different antennas, that's why.

    If you've been wondering when I'll answer the bit about the best antenna, you should already have a clue by now, but the real answer is unsurprisingly: "That depends."

    "On what?" you ask.

    On which ever variables you care about and to which degree. The best antenna depends on the questions you ask. Ask better questions, get a better antenna.

    I'm Onno VK6FLAB

    To listen to the podcast, visit the website: http://podcasts.vk6flab.com/. You can also use your podcast tool of choice and search for my callsign, VK6FLAB. Full instructions on how to listen are here: https://podcasts.vk6flab.com/about/help

    All podcast transcripts are collated and edited in an annual volume which you can find by searching for my callsign on your local Amazon store, or visit my author page: http://amazon.com/author/owh. Volume 7 is out now.

    Feel free to get in touch directly via email: cq@vk6flab.com, follow on twitter: @VK6FLAB (http://twitter.com/vk6flab/) or check the website for more: http://vk6flab.com/

    If you'd like to join a weekly net for new and returning amateurs, check out the details at http://ftroop.vk6flab.com/, the net runs every week on Saturday, from 00:00 to 01:00 UTC on Echolink, IRLP, AllStar Link and 2m FM via various repeaters.
     

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    K5WDS, AC7DD, N4GST and 3 others like this.
  2. W1YW

    W1YW Ham Member QRZ Page

    Uh...we shouldn't "go into the physics of how and why".

    Why not?

    Shouldn't we use our ham radio opportunities as bona fide learning experiences? Invitations?

    Stateside, Part 97 lists as two of its mission keys as :

    "enhance the radio art"

    "provide a pool of technically skilled operators"

    HOW DO YOU ASK: "HOW DO I GET A BETTER ANTENNA"--without physics??


    Please Onno: go into the physics for us.

    73
    Chip W1YW
     
    Last edited: Dec 7, 2018
    ZL1XS, KN4CTD, WB9AZA and 8 others like this.
  3. YO8HMH

    YO8HMH Ham Member QRZ Page

    Build your own Antenna! Do not buy expensive crap from expensive stores. Remember that ads for parts, antennas or HF transceivers are payied by big bussineses .... That's why ham radio equipment is so darn expensive! Be a real HAM, build your own equippment!
     
    Last edited: Dec 7, 2018
    KC5YSQ, KM4BDH, W3LES and 9 others like this.
  4. WN1MB

    WN1MB Ham Member QRZ Page

    Not necessarily true.
     
    W5MBH, N8ZL and K2NCC like this.
  5. WB8VLC

    WB8VLC Ham Member QRZ Page

    What's a Cricket team?

    Maybe you meant to say the local Hockey team perhaps, this is the US Pacific Northwest and Cricket is as foreign to us a politician with integrity.
     
    W5CJA, W3KKO, W5MIL and 6 others like this.
  6. WA6AM

    WA6AM Ham Member QRZ Page

    Antenna's ARE physics. Ya gotta have a basic foundation of physics. It's good stuff! Fun to learn.
     
    W5CJA, KM4BDH, WB9AZA and 3 others like this.
  7. WA1ZMS

    WA1ZMS Ham Member QRZ Page

    Says an old buzzard...
    Unfortunately we tend to have a not-so-insignificant number of people in our fine hobby who poses a "mathematics is hard" mindset. Some amount mathematics is required for physics but not so much that it can't be handled by most with a simple paper and pencil or a calculator.
     
    W5CJA, W5MIL, VK6ATS and 4 others like this.
  8. WQ4G

    WQ4G Ham Member QRZ Page

    I believe that it is possible to build an antenna without KNOWING physics. It's even possible to build rather complex antennas like Yagis and Log Periodics without the knowledge of Physics. Just break out your handy dandy ARRL Antenna book and go at it. All the measurements and dimensions are given therein. If you can follow their drawings and designs you can build an antenna with out one iota of knowledge of Physics.

    This is in no way saying that antennas work without Physics.

    Now, if you want to design your own antennas, or experiment with antennas, or if you want to alter the Antenna Book's designs for different frequencies. Well, then you are going to need some Physics knowledge. Just a little...

    Dan KI4AX
     
    KM5BOR, W5MIL, W4MHZ and 6 others like this.
  9. W1YW

    W1YW Ham Member QRZ Page

    You don't have to know the Gamma functions of oxidation to use gas to cook your dinner. But if you seek to understand the physics concepts, you will understand how to cook evenly and quickly. We are born curious, and you don't need to know the math to dig the physics.
     
    W5MIL, WB9AZA, WN1MB and 2 others like this.
  10. VA3AHQ

    VA3AHQ Ham Member QRZ Page

    There is a joke around our club station.. "We need a better antenna".

    Last weekends FT-8 contest we were heard in Indonesia 14488 KM away on the club built vertical. That made a a few people smile.

    Yes we always need another antenna, right now we are planning to have a group build for a Hexbeam. So far 8 people have signed up... no physics required.. just interest in building something different with a group of hams . :)

    JM
     
    ZL4AV, AC8KJ, KM4BDH and 6 others like this.
  11. KD0CAC

    KD0CAC Ham Member QRZ Page

    You want to build antenna - follow the recipe .
    You want to design an antenna lean some RF physics .
    You want to find out why the home brew or store bought antenna is not working & why , more RF physics .
    " how to get a better antenna " and not get sold a dummy load - again some RF physics - or just trust the salesman ;)
     
    KR3DX, WN1MB and STMJ like this.
  12. SA1CKE

    SA1CKE Premium Subscriber QRZ Page

    You can build an antenna according to specifications, then you discover that the environment around it impacts how it works and you have to tune it to get the most out of it.

    But there are tools for doing it - all it takes is patience, basic knowledge of how to tune an antenna and a good tool. You don't have to know all the physics around it, just a little.
     
    1 person likes this.
  13. AA5CT

    AA5CT Ham Member QRZ Page

    re: " Just break out your handy dandy ARRL Antenna book and go at it."

    I would never have gotten on 160 from my small lot if I followed their precepts ...

    Last night I was spotted by DP0GVN at the south pole and 8 (eight) unique spotters in the EU and UK and TF3GZ in Iceland.
     
    N4GST likes this.
  14. W1YW

    W1YW Ham Member QRZ Page

    Nope. Wrong. Physics most CERTAINLY required.

    Mike Traffie, N1HEX, invented the hexbeam. He took an infinite amount of flack on it back 25 years ago. I know: I saw it.

    The reason? BECAUSE the the claimers of 'snake oil' didn't understand the physics.

    I'm not talking Poynting vector expansions...I mean basic notions of current distribution and constructive and destructive interference, and phase lag.

    Build a hex beam and invite your friends to figure out how it works.

    We're trying to get (even)KIDS to have fun learning physics with STEM. When did ham radio become a 'check your brain at the door' activity? That's not how EVERYONE came in years ago.

    I don't care if (generic 'you', not VAE3AHQ)you didn't finish the 6th grade. If you are curious and like using your hands, you should like using your head. If someone kicked you in the head and turned you off, consider ham radio more welcoming than that.
     
    Last edited: Dec 8, 2018
    1 person likes this.
  15. AA5CT

    AA5CT Ham Member QRZ Page

    Wanna hear something radical? It has been my observation that dipole antennas (i.e. 1/2 Lamda or 1/2 wave electrical wavelength doublets) "radiate" using the magnetic field, which means it is predominantly from the area near the center. You won't find that stated in very many pubs or sources, and certainly does not appear in League publications ...

    A corollary to that: The function of an antenna's structure is to create a strong enough "reactive" magnetic (or electric field) at 1/4 WL distance from said antenna such that effective radiation takes place according to Maxwell, ie, no magnetic monopoles et al ...

    And anything beyond the dipole (Franklin, Yagi, etc.) is superposition, i.e., constructive and destructive wave interference.
     
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