End fed antennas and gauge/type of wire used.

Discussion in 'Ham Radio Discussions' started by KB0TTL, Mar 14, 2021.

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  1. KB0TTL

    KB0TTL Ham Member QRZ Page

    20210313_182015.jpg
    To the left, I have my trusty 49:1 balun with 64ft of 20AWG single copper strand insulated wire which was mounted for 3 months. I was successful at making several QSO's on it, however, the UV rays quickly took a toll on the insulation (notice how the wire is now pink instead of bright red, and practically white in some places). Next to it is some 22AWG multi-stranded aerospace quality wire which I was using on a similar endfed in my back yard. That particular wire had been outside for almost a year and still looks to be in the same condition it was when I put it up. I have talked to Russia, Central America, Bulgaria, and Europe on the wire in the middle with no problems. Next to it (right) is a random spool of multi-strand 14AWG that I just got off of eBay. I replaced my existing endfed element with it this afternoon in hopes of gaining some extra bandwidth. So far, audio reports have been good and we will see how well it holds up this summer. While I may gain some extra bandwidth using the heaver gauge wire, it is doubtful that I will see any dramatic increase in the number of stations worked because propagation conditions basically "are what they are" at any given time. I have seen that most commercially available endfed and traditional dipole kits use the 14AWG as well, and I am wondering if there is a particular reason for this. Folks, what kind of wire do you normally use, and what have your experiences been?
     
  2. N5PAR

    N5PAR Ham Member QRZ Page

    My 80 meter inverted V is made from the black and white coated 16 gage wire from a wore out 100 foot outdoor extension cord. It been in use for 6 or 7 years. Still works great. I did seal all the connections with silicone sealer. The reason I think for using heavy gage wire is durability. I know that bigger gage wire is supposed to help with more band width but I’m not really sure there is much difference between 18 or 20 gage wire and 14 in reference to gaining bandwidth.
     
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  3. KE0VT

    KE0VT Ham Member QRZ Page

    I don't think you will gain any bandwidth. If bandwidth is what you want terminate a dipole to a resistor. The downside though is high loss in the signal. I have a BBTB in my attic, very good bandwidth,
    average signal report is 5 x 4 with an occasional 5 x 9. I am barefoot with 100W. The dipole is 14 gauge stranded, insulated. Look up Butterfly broadband terminated dipole on google. The balun and
    resistor are available from Palomar Engineers.

    The UV rays have no bearing on the signal. If you had left it up for a year I'm sure you would have worked the DX as well.

    73
     
  4. KC3PBI

    KC3PBI Ham Member QRZ Page

    I've got a 142' end-fed wire in 14awg and a second 130' wire in 18awg. I can see the bandwidth difference on my VNA and on my rig's SWR meter, but in practical use it hasn't mattered at all.

    Both are solid copper, both were sold for direct burial invisible dog fence usage. No dog, but I happened to have a few thousand feet lying around already paid for so I went for it.
     
  5. WA9SVD

    WA9SVD Ham Member QRZ Page

    Probably the only significant difference you will see, concerning different wire(s) is there will be a slight difference in absolute length for a given resonant frequency; (almost) ALL antennas get trimmed a bit, depending on their exact installation/ location. What may have a slightly greater effect is insulated vs. bare wire. The insulation results in a slightly shorter required length than bare wire, so if the insulation sloughs off due to weather/elements, the actual resonant frequency of an antenna will change upward! Other than that, the wire must be of sufficient diameter to be self-supporting. But the bandwidth of a (single wire) dipole (or end-fed antenna ) will not measurably be changed due to diameter. (One reason to use a larger gauge wire is that at the RF frequencies WE use, skin effect becomes important, so a larger wire may have slightly [very slightly] lower radiation resistance.)
     
  6. W7HV

    W7HV Ham Member QRZ Page

    FWIW: The current distribution and voltage distribution in a 1/2 wave end-fed is exactly the same as in a resonant dipole, which is also 1/2 wave in total length, so the fundamental performance and effects of things like wire gauge will be the same. With the dipole, the 1/2 wavelength wire is being fed in the middle, at the current maximum, so the impedance is low. An end-fed feeds it at the end, which is a current node, so the impedance is very high, but the current max in the center of that wire is the same as it is for a dipole.

    Modeling these antennas in modeling programs like EZNEC will illustrate this.
     
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  7. W7IMM

    W7IMM Ham Member QRZ Page

    I am glad you said this! End fed antennas are so frequently misunderstood!

    a 1/2 wave dipole is still a dipole regardless of how or where you "feed" it!!

    I have used an end fed wire for over 20 years connected to an SGC SG235 Smart Tuner I bought new in 1997. I started with an approx 200' (203' to be exact) piece of wire about 30-50 ft up made of #18 copper-clad steel wire. It was up there for all those years and never came down of it's own accord!

    For most of those years It performed only "OK" on 160, 80 and 40. I used a copper ground rod and a single 300ft piece of wire buried below it.

    About 2 years ago, I decided to try more wire on the ground. So I completely disconnected the copper ground rod and connected 5-135ft "radials" to the ground connection of the SGC coupler and was amazed at the huge increase in performance on all the above bands!

    I now use a 240ft center fed (with open wire) dipole on the same 3 bands. and have since removed all the wire on the ground (got tired of my wife threatening to run over them with the mower!!)

    The Centerfed 240ft dipole GREATLY outperforms the end fed wire on all bands using the same type of Pi-L relay-switched tuner.

    Now having said that, For the OP, if you want to continue using an end fed antenna, get a similar tuner (SGC, SEA, MFJ, ICOM AH-4 or a manual Pi-L tuner) and ensure that you have at least 3 or 4 times as much wire on the ground as in the air and it'll work just fine!

    Cheers,

    Rick
     
    Last edited: Mar 14, 2021
    KB0TTL likes this.
  8. KA4DPO

    KA4DPO Platinum Subscriber Platinum Subscriber QRZ Page


    So is it a Balun or an Un-Un, big difference. As for the question, any wire gage will work at 100 watts as long as it is sturdy enough to stay up. So what exactly does the 49:1 transformer do? At what frequency, or frequencies, does the end of your wire exhibit an impedance of 2450 ohms, and is it reactive, and what sign is it?

    Sorry, just making a point. If yo want an end fed antenna that really works well, there is a well known way to do it. Select a wire length that is not a half wave, or multiple of a half wave, on any bands that you plan to use it on. Lay down a radial field, a counterpoise is imperative for efficient operation, the more wire the better. And use a variable tuner like an L or T network, and not an Un-Un.

    And for the record, there is no such thing as an end fed dipole, a dipole is fed in the middle, or off center. An end fed antenna is a monopole, just like a vertical antenna. An end fed antenna can not provide any more gain that a dipole antenna of similar dimension and height above ground. The best, and easiest multiband antenna is a center fed flat top, fed with 450 or 300 ohm ladder line into a balanced tuner. Have fun and keep on experimenting.
     
  9. W4HRL

    W4HRL XML Subscriber QRZ Page

    I almost hate to jump into another “end-fed” thread because they some times turn ugly. But here goes…..

    There is considerable difference between the two most common configurations of end-fed antennas.

    The first configuration uses a 9:1 transformer and a wire that is NOT a half wave at any frequency in the Ham bands. This set up requires a radial field and a tuner to cover your bands of interest.

    The second configuration uses a 49:1 transformer and a wire that IS a half wave length at the lowest frequency of interest. No radial field required but you do need a single “radial” equal to 0.05 wavelength (at lowest frequency). A 1:1 RF choke is needed to control common mode current. Some folks insert this choke 0.05 wavelength down the line and use the coax as their “radial”. Others put the choke immediately downstream of the 49:1 box and use a separate 0.05 wavelength “radial”.

    Using this 49:1 setup, once the wire is properly trimmed, you do not need a tuner. The antenna is exhibits a low (usually 1.5 : 1) SWR on all harmonic bands. A 66-foot wire will give you 40, 20, 15, and 10 meters (i.e. no WARC bands), while a 132-foot wire will give you all that plus the WARC bands without a tuner.

    I am a fan of the 49:1 transformer configuration. Due to my particular yard layout, I like mine erected as an inverted – L with a 25-foot vertical section and the rest running horizontal.

    I usually run a 66-foot wire because 20 meters is my favorite band these days and I like the radiation pattern for 20 meters better on the 66-foot wire than the 132-foot wire. Has to do with the various lobes created and their direction.

    As to the original poster’s question, I use 18 gauge PolyStealth wire from Davis RF (http://davisrf.com/antenna-wire/polystealth.php).

    There are many folks who passionately believe “An end-fed antenna using a 49:1 transformer and no real radials will not work.” It definitely is not equal to a multi-element Yagi on a large tower, but it does work. Using only a 100 watts and my 49:1 end-fed, I have over 160 LoTW-confirmed contacts in my log book.

    Cheers,
    W4HRL
    Mike in Poquoson VA
     
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  10. W4HRL

    W4HRL XML Subscriber QRZ Page

    I hit the send button too fast, and QRZ is not letting me edit the above post at the moment. The last line should read:

    "Using only a 100 watts and my 49:1 end-fed, I have over 160 LoTW-confirmed countries in my log book." About 4000 contacts.

    W4HRL
     
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