Antenna question(s)

Discussion in 'Communications' started by Flashpoint, Sep 29, 2019.

  1. Flashpoint

    Flashpoint Member Charter Member Supporting Member

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    So I bought a couple of the Baofeng UV-5Rs before the big ban, lol and am now looking into getting my license so I can legally transmit. I know a little about radio being a former electronic tech and repairman for radio frequency test equipment but that was all internal to the equipment and have no practical experience with antennas, etc.

    I see antennas for sale of all lengths for these radios. I understand they are dual band and cover VHF and UHF for which I guess a fixed length antenna acts as a 1/4 wave for one band and 1/2 wave for the other, but it seems like they should all be the same length, or multiples of the same length.

    In addition to the radios I bought 14.5" ExpertPower XP-771 whips which get god reviews to replace the stock antennas and this SWR meter: https://www.amazon.com/gp/product/B075H8FDDR/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

    What I'm seeing is that the stock rubber duckies only get below 1.5 SWR in a narrow VHF range, and the whips do the same but only in the UHF band.

    So my question is this: Will a longer antenna perform better with a slightly higher SWR than a significantly shorter antenna, say a length ratio of 2:1?

    And finally, what's the best handheld antenna you know of? I'm also interested in a full wave wire antenna (the kind you throw over a tree limb). There is one on amazon but it's $60, seems like a lot for a piece of wire and coax.
     
  2. JohnFreeman

    JohnFreeman The bane of my existence Benefactor Charter Life Member

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    Good questions, but of course the answers aren't simple!

    Flexy "rubber duck" antennas are pretty awful , especially the smaller ones.

    Bigger doesn't mean better necessarily (for example if it's wound with small wire, it may be worse because of resistive losses) but generally it is. The antenna you got is a good selection. An antenna with a relatively narrow low-swr bandwidth is a good thing, not a bad thing.

    Two methods for better handheld performance.... a full size 19" whip made out of anything conductive is going to be better than any of the short antennas (using 2M as an example. 19" ~ 1/4 wavelength at 146 Mhz) . Secondly (and more practical) a 19" wire hanging off the antenna connector (connected to the ground portion of the connector ...SMA/SMB/BNC--- not sure what you have) will make a big difference. The whip (whatever form it is) is typically pretty inefficient as it's like half of a dipole... missing its ground. So , provide a 1/4 wave ground "plane" by attaching 19" of wire soldered to a washer that will fit between the antenna and the antenna connector on the radio.

    "Best" home antennas ... define what you want to use it for and what price range, and I'll help with "best". If you're trying for SSB 2m interstate/DX communications, there's one answer. If you want something to talk on the local repeaters with, there's another. An antenna is a tool, so "best" depends on the job at hand.

    Keep asking!
    John

    PS: How do you know the antenna works at 1:5/1 if you don't have a license ? Just asking.

    PPS: $60 for a wire antenna at 2M is indeed ridiculously expensive

    PPPS: Rubber duck antennas are different lengths, because

    * They're pretty close to the actual 1/4 wave length, just spiraled around a core
    * They're "electrically lengthened" by adding a series inductor (see ^)
    * They're actually just random pieces of wire stuffed into a really small flexible covering because just about anything will hit a repeater from a few miles away
    * etc
     
    Last edited: Sep 29, 2019
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  3. Flashpoint

    Flashpoint Member Charter Member Supporting Member

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    Thanks for the very informative and prompt reply John!

    JohnFreeman, post:

    An antenna with a relatively narrow low-swr bandwidth is a good thing, not a bad thing.
    I would think having a low swr across a broad range would be better than a narrow range? But I guess this is normal?

    I guess if you had the ability to tune your antenna/swr to be optimum for a freq you know you will always use then you could get better performance for that freq but these radios are expected to perform adequately across the bands, right?

    Secondly (and more practical) a 19" wire hanging off the antenna connector (connected to the ground portion of the connector ...SMA/SMB/BNC--- not sure what you have) will make a big difference. The whip (whatever form it is) is typically pretty inefficient as it's like half of a dipole... missing its ground. So , provide a 1/4 wave ground "plane" by attaching 19" of wire soldered to a washer that will fit between the antenna and the antenna connector on the radio.
    It's funny you mention that as I just watched a couple of Youtube videos on that last night, it's called a "Counterpoise", right? It seemed the jury was out on how effective it is but I get why it should work.

    "Best" home antennas ... define what you want to use it for and what price range, and I'll help with "best". If you're trying for SSB 2m interstate/DX communications, there's one answer. If you want something to talk on the local repeaters with, there's another. An antenna is a tool, so "best" depends on the job at hand.
    My home is not suited for Ham very well I don't think. I live on a farm and where the house is shaded with trees all around, in fact the nearest option in clear space would be bolting something to a fence post 200-300 yards away.

    PS: How do you know the antenna works at 1:5/1 if you don't have a license ? Just asking.
    Good question yourself! :D I did key the mike briefly at 1 watt from inside my metal roofed house (no one gets cell signal inside this house) a few times, maybe 8 - 10 times for a couple of seconds each. I am over 11 miles as the crow flies from any municipalities and I looked up the county's pd, & ems/fire frequencies and made sure I stayed away from those. In fact I started with MURS and FRS frequencies, but did check a couple others, in all cases monitoring first but basically can't hear anything but FM while inside. I can't even get the noaa channels from inside my house. So I expect I broke the letter of the law, but I'm convinced it mattered less in the real world than me driving almost 10 miles over the speed limit on the way home. Please don't hesitate to correct me if I'm looking at this wrong. I hope I didn't sound too defensive. lol.
     
    Last edited: Sep 29, 2019
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  4. Button Pusher

    Button Pusher Well-Known Member Benefactor Supporting Member

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    One thing to keep in mind, these tiny handheld radios do not have the filtering that a full sized or mobile radio has,
    better antenna bring in the good, the bad and the ugly signals.
    Check out this interesting antenna for two meters, the half square. Turns a few heads at the club meetings.
    Hang it on the wall or inside the window.

    half sq 2m.gif
     
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  5. Jtkazanjian

    Jtkazanjian New Member

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    I have a bf-f8hp that I have had for a while with. Nagoya na-771 15 inch antenna on it. I have no ham license so I just listen. Im in Mooresville and I can pick up 4 noa weather channels. Can listen to repeater in Statesville, maiden, concord, Morganton, wilkesboro, Mooresville, and one out of Charlotte. If I can hear them will they hear me once I get my license?
     
    Last edited: Sep 29, 2019
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  6. hp468

    hp468 Member Supporting Member

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    The answer is MAYBE. It totally depends on how the repeater is set up. Elevation, antenna, Rx sensitivity, Tx output, etc. Some repeaters out talk their ears and some repeaters can hear further than they can talk. Check with the groups that run the repeaters and see if they have coverage maps listed on their web site. Keep in mind that you are running a 5w handheld, the repeater may be running anywhere from 25-100w so if your on the outskirts you may not make the trip. Only way to know is to throw your call sign out(once you get your ticket).
     
  7. Flashpoint

    Flashpoint Member Charter Member Supporting Member

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    I can pick up noaa in Chapel Hill and GSO standing outside my house, but inside under that metal roof I can't hear them very well at all. There is a shed porch all the way around the house with a metal roof as well, so it really does a number on reception and I assume transmission as well.

    The house is also essentially in the woods, surrounded by 100+ ft tall trees. Would it be worth it to even try to set up a home antenna? How much signal do trees block?

    I wasn't intending necessarily to get into ham in a big way, just want a way to communicate with scouts up to a few miles away from the homestead in a SHTF/WROL scenario mostly. If the trees aren't a big problem I might try and set up a home rig though. Just what I need, one more hobby I don't have time for! :rolleyes:
     
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  8. Button Pusher

    Button Pusher Well-Known Member Benefactor Supporting Member

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    FM is line of sight while the lower HF bands vary with the atmosphere. Trees have water in them and that also plays into this.
    FRS radios are another option, find them everywhere and no license needed unless you are using it for business then other options are better.
     
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  9. Flashpoint

    Flashpoint Member Charter Member Supporting Member

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    Yeah I know trees affect radio waves because of their moisture which is a conductor. I was just looking for a rule of thumb, like don't bother if you are in trees, or something like that. :) I bought the Baofengs because like everyone else I didn't want to be limited to the power or frequency range of FRS radios.
     
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  10. hp468

    hp468 Member Supporting Member

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    You might be surprised what some repeater sites can accomplish. I can sit in my living room on one of these uv5r's (about 7 miles as the crow flies from our 2m repeater site) hear and talk to it just fine, some white noise but perfectly acceptable. I've talked to our 70cm site with a 4w handheld from roughly 35mi away.

    Line of sight is a beautiful thing with UHF and VHF freqs, keep in mind you can also talk to the space station and satellites with one of these and a yagi antenna.

    @Flashpoint if you pm me an email address I can shoot you a plot of a repeater site to give you an idea of what these little guys can do when the repeater is doing its part.
    .
     
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  11. JohnFreeman

    JohnFreeman The bane of my existence Benefactor Charter Life Member

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    Thanks for the very informative and prompt reply John!

    ^^ Sure, I'll try to be more timely in responses

    JohnFreeman, post:

    An antenna with a relatively narrow low-swr bandwidth is a good thing, not a bad thing.
    I would think having a low swr across a broad range would be better than a narrow range? But I guess this is normal?


    ^^ Having a low swr across a wide part of the spectrum is handy, but it's also like a free lunch! Antennas that exhibit such a response are generally very lossy and achieve that wide frequency response by turning a lot of your transmit power into heat.... NOT what you want. While there's some "bands" that have a favorable wavelength to bandwidth ratio, there's others (like 75/80 M) where if you get a flat response across the whole band, you're feeding a heater :)

    I guess if you had the ability to tune your antenna/swr to be optimum for a freq you know you will always use then you could get better performance for that freq but these radios are expected to perform adequately across the bands, right?

    ^^ Yes... correct. In a practical sense though, worrying about SWR across most band segments is not worth worrying about as long as SWR < 2:1 or so in most typical ham situations. Exceptions would be very long coaxial feedlines at VHF and above.

    Tuning the antenna though, means changing the length of the elements, not just adding reactance at the transmitter end of the coax line (as an "antenna tuner" generally does)

    Secondly (and more practical) a 19" wire hanging off the antenna connector (connected to the ground portion of the connector ...SMA/SMB/BNC--- not sure what you have) will make a big difference. The whip (whatever form it is) is typically pretty inefficient as it's like half of a dipole... missing its ground. So , provide a 1/4 wave ground "plane" by attaching 19" of wire soldered to a washer that will fit between the antenna and the antenna connector on the radio.
    It's funny you mention that as I just watched a couple of Youtube videos on that last night, it's called a "Counterpoise", right? It seemed the jury was out on how effective it is but I get why it should work.

    ^^^ It is indeed, and it will ALWAYS improve the response of any handheld radio feeding some version of an end fed antenna (like a 1/4 wave vertical)

    "Best" home antennas ... define what you want to use it for and what price range, and I'll help with "best". If you're trying for SSB 2m interstate/DX communications, there's one answer. If you want something to talk on the local repeaters with, there's another. An antenna is a tool, so "best" depends on the job at hand.
    My home is not suited for Ham very well I don't think. I live on a farm and where the house is shaded with trees all around, in fact the nearest option in clear space would be bolting something to a fence post 200-300 yards away.

    ^^^^^Trees don't make a huge difference in a practical sense.... the feedline loss from 200 yards of coax is much much more than the loss due to heating tree sap. Use the trees to put an antenna up high and you're coming out ahead over a flat pasture , and a low mounted antenna in the clear. This is particularly the case at HF. While I'm not a serious DX chaser on the High Frequency bands, I'm ONE contact short of 7 band DXCC confirmed and am just shy of 300 countries worked and confirmed. My antenna is a 3 active element beam for 10-20 buried in the trees in my back woods. Pines and hardwoods are 60-70 feet, the antennas are at 50 feet. :)
     
    Last edited: Oct 6, 2019
  12. JohnFreeman

    JohnFreeman The bane of my existence Benefactor Charter Life Member

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    You're right ! A metal roof will shield your signal very effectively . On the other hand, you can use it to your advantage in an easy way.

    Order a magnetic mount 1/4 wave mobile vertical antenna, install the mag mount as far into your roof/patio cover as you can reach and enjoy ground plane goodness! That sheet metal roof is a perfect counterpoise. You'll be impressed with the difference (even with the cheezy chinese coax these things come with). This is probably about a 20$ experiment these days.

    When you're done with that, replace the squiggly antenna that these come with , with a 19.5" piece of straightened out coat hanger into that same mag mount, and enjoy even better performance. Replace the coax with better stuff and yet more incremental improvement. Replace the mag mount with a DC connected "ground" to the porch metal instead of the capacitive coupling of the mag mount and you're still gaining ground.....
     
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  13. Flashpoint

    Flashpoint Member Charter Member Supporting Member

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    Some excellent suggestions! Thanks and I really appreciate knowing that trees won't absorb the signal as much as I had feared.
     
  14. rdinatal

    rdinatal Better late then never...

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    Why not just skip the $40 Baofeng UV-5R and go right to the $1500+ base unit? :rolleyes:
     
    Last edited: Oct 8, 2019
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  15. JohnFreeman

    JohnFreeman The bane of my existence Benefactor Charter Life Member

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    Shhhh! Gotta get 'em to at least General before the $ mission creep appears!

    Besides most of these improvements are pretty much free.... just a little effort and experimentation.

    The fancy HF base transceivers are WAY more than that. :) (I don't have one!)

    John
     
    Last edited: Oct 8, 2019