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  • building an antenna

    From mark lewis@1:3634/12.73 to all on Thu Jun 13 15:16:00 2019

    this is somewhat on the topic of HAM but the actual use is not... i don't know where to look for the information i'm seeking...

    here's the scenario:

    i need to make an external UHF HD antenna...
    i do not have any funds available...
    i found plans for a UHF antenna online and printed them out...
    they are using some copper tubing that is wrapped half around a 26inch bicycle rim for shaping...
    the bicycle rim is only for shaping... it is not used for the actual antenna...
    there are two halves each making one half of a circle...
    the two halves are mounted on PVC members to hold them...
    the circle is horizontal to the ground...

    so in simple terms, this is a dipole antenna that is circular so as to be uni-directional...

    what i want to do is to make four halves and mount the second two 90 degrees out to avoid any (slight?) blind spots as well as to provide more area to pick up the signals... what i'm not sure of is how far apart the two antenna circles should be mounted from each other or how long the inter-connecting wires between the two circles must/can be...

    i'm taking the idea roughly from a turnstyle dipole antenna that has 16 bowtie halves where the bowties are a specific distance apart... and cross wired from bowtie half to bowtie half... i don't know the proper terms for these cross wires connecting the bowtie halves, though...

    i was (slowly) in the process of making the bowties (from some 10/2 electrical wire) when someone (don't ask, bad shituation) took all my copper and now i don't have any to build even that antenna any more... i also wanted to make a simpler antenna... i absolutely want one that is unidirectional because i do not want to have to go and be turning the dang thing just to watch different TV channels... our existing rotor is dead and i'm certainly not in the position to purchase another one... so a friend has offered to provide enough copper tubing/pipe to make the antenna and if it works well, they want one, too...

    so, two stacked circular dipole antennas with one circle turned 90 degrees around the pole axis from the other circle... how far apart do the two circles need to be? how long can the cross-connect wires be to link the two circles to the balun/adapter where the 50ohm RG58 connects?

    here's a link to an antenna that is very similar to what i'm looking to make... i'm just looking at doubling the number of circles and connecting them together properly...

    https://www.instructables.com/id/Homemade-TV-antenna/

    advTHANKSance!

    )\/(ark

    Always Mount a Scratch Monkey
    Do you manage your own servers? If you are not running an IDS/IPS yer doin' it wrong...
    ... Lots of beef and oceans of grog. (Navy)
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    * Origin: (1:3634/12.73)
  • From Ed Vance@1:2320/105 to mark lewis on Fri Jun 14 20:56:00 2019
    06-13-19 15:16 mark lewis wrote to all about building an antenna
    Howdy! Mark,

    @MSGID: <5D02D5B5.9581.fi_ham@capitolcityonline.net>

    this is somewhat on the topic of HAM but the actual use is not... i
    don't know where to look for the information i'm seeking...

    here's the scenario:

    i need to make an external UHF HD antenna...
    i do not have any funds available...
    i found plans for a UHF antenna online and printed them out...
    -BIG SNIP-

    I started reading Your message and after TEN Lines I decided to tell You
    how I made a UHF TV Antenna.

    I used a piece of 300 Ohm Twin Line cable to make a Folded Dipole Antenna

    a bit over 26 Centimeters long for UHF Channel 32 back in the 1960's.

    Channel 32 had just come on the Air and it's Transmitter was about 4 miles
    from where I lived.

    We bought a UHF to VHF Tuner for the upstairs VHF TV Set, and needed a
    antenna up there, I knew enough to make a antenna by looking in some
    books for Charts and Formulas and made it.

    Channel 32 uses the Band of Frequencies from 578 Mc. to 584 Mc.

    |<---------------------- 26 CM ------------------------>| = 1/2 wave length

    ---------------------------------------------------------
    | |
    -------------------------- -----------------------------
    | |
    | |
    | | Another piece of 300 Ohm Twinline
    | | <-- to Antenna Terminals on UHF Tuner


    I stripped the wires on each end and soldered them together.

    I folded the cable end to end to find the center,

    then I cut one of the wires at the center,

    and attached another piece of 300 Ohm Twin Line to each of the center wires
    for a feed line to the UHF Tuner.

    I taped the Home Brew "Antenna" to the wall.

    It worked!

    You could use a 2 pieces of PVC pipe and a TEE to enclose the Folded Dipole
    or DUCT TAPE the antenna to a board, to make it an External Antenna.


    <<<<<<<<<<<<<<< BRAGGING MODE ON >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

    I told a neighbor about the antenna I made and was asked if I would make
    one for them, so I went to the Wire Box, grabbed a length of 300 Ohm Twin
    Lead, put it together and fastened it to the neighbors UHF Tuner.

    BRAGGING MODE OFF <<<<<<<<<<<<<<<<<<<<<<<<<<<<<

    73 de Ed W9ODR . .


    ... Have you checked your smoke detector batteries & Fire Ext, LATELY?!
    --- MultiMail/MS-DOS v0.49
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)
  • From Ed Vance@1:2320/105 to mark lewis on Fri Jun 14 21:23:00 2019
    06-13-19 15:16 mark lewis wrote to all about building an antenna
    Howdy! Again Mark,

    @MSGID: <5D02D5B5.9581.fi_ham@capitolcityonline.net>

    this is somewhat on the topic of HAM but the actual use is not... i
    don't know where to look for the information i'm seeking...

    here's the scenario:

    i need to make an external UHF HD antenna...
    i do not have any funds available...

    ---ANOTHER BIG SNIP---

    I just read another part of your message and thought to write that you
    could get a round piece of wood and wrap the folded dipole around it.

    I have a Halo Antenna for 50 Mc., mine has one loop of small aluminum tubing.

    Another brand I could had bought had 3 loops - each one stacked above the other.

    Halo Antennas were also made for the 146 Mc. Ham Band.

    73 de Ed W9ODR . .




    ... so I hit him back first.
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    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)
  • From mark lewis@1:3634/12.73 to Ed Vance on Sat Jun 15 11:07:24 2019

    On 2019 Jun 14 20:56:00, you wrote to me:

    I used a piece of 300 Ohm Twin Line cable to make a Folded Dipole Antenna

    the problem with that is it is flat and you have to rotate it to be broadside to the station you are wanting to pick up... i'm looking to build an omnidirectional one so i do not have to rotate the antenna at all...

    i think i wrote unidirectional previously but i meant omnidirectional :/

    a bit over 26 Centimeters long for UHF Channel 32 back in the 1960's.

    26cm? like 10.25 inches? that seems a little short but it is half-wave...

    Channel 32 uses the Band of Frequencies from 578 Mc. to 584 Mc.

    yeah, the UHF band is 470mhz to 890mhz... your freqs there are pretty close to right in the middle which is 683mhz...

    )\/(ark

    Always Mount a Scratch Monkey
    Do you manage your own servers? If you are not running an IDS/IPS yer doin' it wrong...
    ... Enquiring minds couldn't care less!
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    * Origin: (1:3634/12.73)
  • From mark lewis@1:3634/12.73 to Ed Vance on Sat Jun 15 11:03:28 2019

    On 2019 Jun 14 21:23:00, you wrote to me:

    I just read another part of your message and thought to write that you could get a round piece of wood and wrap the folded dipole around it.

    i was wondering about that...

    I have a Halo Antenna for 50 Mc., mine has one loop of small aluminum tubing.

    we've thought about using aluminum, too... just a matter of bending it without collapsing the tube...

    Another brand I could had bought had 3 loops - each one stacked above
    the other.

    this sounds like what i described that i want to do... that's why i was asking about the spacing between the loops and if it is critical or not...

    Halo Antennas were also made for the 146 Mc. Ham Band.

    ahhh... halo antenna... another search term to play with ;)

    )\/(ark

    Always Mount a Scratch Monkey
    Do you manage your own servers? If you are not running an IDS/IPS yer doin' it wrong...
    ... Cannibalism is a small price to pay for popularity.
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    * Origin: (1:3634/12.73)