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Offline JohnyMac

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Making Antenna's
« on: July 21, 2016, 09:48:04 AM »
Being an under-financed new ham (Amateur Radio Operator), making things is part of the game. Working with a Baofeng handheld VHF radio with a max of 5Watt output, makes it especially challenging to pick up the local repeater ~30 miles away.

My first attempt at an antenna was to make a
dipole antenna. After viewing a few YT videos, I carefully measuring the lengths of the wires used in the making of the antenna. This simple antenna has served us well at the cabin till now.

Unfortunately, the 5W radio was too under powered to "ping" the local repeater. So I moved onto a Moxon antenna.

The Moxon antenna is a directional antenna unlike the all around wave of dipole antenna. With a directional antenna you can direct the wave in one direction. Like the dipole antenna it is important that you cut and place the wires exactly. Once completed I was able to ping the repeater and carry on several two way conversations. YAHOO!

Being a type "A" personality I wanted MORE so I had to make a
2 Meter Quarter Wave Antenna
(QWA). Not unlike the aforementioned antennas measuring & cutting of the wire is so important.

Last night the local amateur radio club uses the repeater I have been trying to ping for a one hour rag-chew. When it was my turn to talk it was reported that I was being heard 5x5 (Perfect sound). Now that 5x5 was with a $30- Chinese VHF handheld radio, putting out 5W, 30 miles away.  :dance:

So what is my next project?

   

 

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Offline Nemo

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Re: Making Antenna's
« Reply #1 on: July 21, 2016, 07:00:52 PM »
Something like that I guess a dance is appropriate.

Nemo   (see below, need to add that to the [more] link)
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Offline APX808

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Re: Making Antenna's
« Reply #2 on: July 21, 2016, 09:21:20 PM »
Hey John drop us a few pictures of your home made antenna ;)

I just added the bacon dance to the [more] smileys pop up  :baconDance:
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Offline Nemo

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Re: Making Antenna's
« Reply #3 on: July 22, 2016, 01:04:16 AM »
Home made antennaes he described are cool.  So is Bacon Dance.

Nemo*   :baconDance:

*Posted this just to be able to put the bacondace up again!
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Offline JohnyMac

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Re: Making Antenna's
« Reply #4 on: July 22, 2016, 08:59:51 AM »
No worries APX.

Attached are three pic's. The first is a Moxon and the two others are a close up and step back of the 1/4 ground plane antenna.

Moxon
> The structure I used to mount the 12 gauge wire is 1/2" PVC pipe.
> Cut then assembled the PVC pipe then mounted wire to PVC pipe using electrical tape.
> Once the wire was mounted, I went back and measured then cut wire to specifications.
> The leads for the coax are just affixed to # 10 SS screws with nuts drilled through the PVC pipe.
> The coax used was RG 8X, 50 ohm with one male PL 259 connector and the end attached to the leads on the #10 screws. 
> Last I made a RF choke coil with 5 wraps of the
   coax.

Last night I was rag chewing (Talking) with a few hams and a guy joined in from Albany ~100 miles away. Again this is a directional antenna. The wave is directed towards a specific direction.

Quarter Ground Plane
> Used a 10' section of 3/4" PVC pipe.
> The hardware was:
    - 2, PL 259 Male connectors
    - 50' of RG 8X, 50 ohm coax
    - 1, SO 239 Chassis connector
    - 4, # 6 machine screws, washers and nuts
    - 5, bare 12 Gauge wires cut to length.
    - 2, brackets to hold PVC/Antenna

This antenna, although not a directional one, I was able to ping another repeater south ~55 miles away. 

Questions?   :))
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Offline APX808

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Re: Making Antenna's
« Reply #5 on: July 22, 2016, 09:21:09 PM »
Really cool craftmanship John ;)

For what band is the moxon antenna?
Did you have to use an antenna tunner?
Can you use HF yet or you need to continue evolving your license to go HF? Here in Argentina you don't have all bands free with the initial licence, you need to do some challenges and spent some time as a HAM to get access to them.
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Offline Nemo

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Re: Making Antenna's
« Reply #6 on: July 23, 2016, 10:25:25 AM »
The plastic pipe is NOT the antennae, correct? 

That wire inside the pipe acts to pick up radio signals from inside the pipe, correct? 

The pipe is to hold the wire in proper shape so it gets max function, correct?

Does the pipe block any signals and reduce the sensitivity of the antennae?

Nemo
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Offline JohnyMac

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Re: Making Antenna's
« Reply #7 on: July 23, 2016, 10:51:31 AM »
Responses in bold.

@ APX:
For what band is the moxon antenna? Any band you just have to cut the wire (s) to match the band. In my inital post I included the AP that reports the length you need to cut.

Did you have to use an antenna tunner? Nope. That is what is cool about cutting the wire to exact specifications. When I use the calculator I aim for the middle of the band. In the 2 Meter band that would 146.000. In the 6 Meter band the mid point is 55.000. etc

Can you use HF yet or you need to continue evolving your license to go HF? Here in Argentina you don't have all bands free with the initial licence, you need to do some challenges and spent some time as a HAM to get access to them.Same here in the States. I have a Technical License. I can use all of the UHF & VHF bands, all of the 6 Meter and about half of 10 Meter bands. I can use CW (Morse Code) on all bands. Once I get my General license, I will almost be able to use all bands.

@ Nemo:
The plastic pipe is NOT the antennae, correct? Correct. The PVC pipe is just the structure. The wire is taped to the outside.

That wire inside the pipe acts to pick up radio signals from inside the pipe, correct? No. The wire is taped to the outside of the pipe. It is on the opposite side from what you see in the picture. I couldn't take the pic looking east (Wire on the west side of the PVC) because the sun was coming up.

The pipe is to hold the wire in proper shape so it gets max function, correct? Yes. Like a skeleton. You could use 6 Gauge copper welding rods if you choose and then no skeleton would be needed.

Does the pipe block any signals and reduce the sensitivity of the antennae? Nope. Again the wire is outside the PVC tube. The PVC tube just acts as a skeleton.

Great questions gents! Keep 'em coming.

Just a side note: The tuners function is to artificially lengthen/shorten a wire length. If you pre cut the wire to match your band you no not need a tuner.   
« Last Edit: July 25, 2016, 12:25:47 PM by JohnyMac »
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Offline Nemo

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Re: Making Antenna's
« Reply #8 on: July 23, 2016, 02:27:39 PM »
Quote from: JohnyMac on July 23, 2016, 10:51:31 AM

Great questions gents! Keep 'em coming.

Just a side note: The tuners function is to artificially lengthen/shorten a wire length. If you pre cut the wire to match your band you no not need a tuner.   

How precise does the wire length need to be.  Inch?  3 inches?  Foot?  Centimeter?  Meter?

Can you easily add X length to change frequencies?

How variable is frequency change? 

Can you easily go to a second freq?  Go up and cover all between and to the 8th?  To the 42?

Nemo
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Offline JohnyMac

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Re: Making Antenna's
« Reply #9 on: July 24, 2016, 08:45:57 AM »
Response in bold.

@ Nemo:
How precise does the wire length need to be.  Inch?  3 inches?  Foot?  Centimeter?  Meter?I use meters (CM) and double check with inches and fractions there of. I am a "A" type person so I cut exactly what the converter that I included the link to at the beginning of this thread recommends.

Can you easily add X length to change frequencies? Easy is a relative term. It would be easier to just cut a new length.

How variable is frequency change? Sorry, I have only had 1 cup of coffee so far - I don't understand your question.

Can you easily go to a second freq?  Go up and cover all between and to the 8th?  To the 42? Sure, if you change antenna's. Just a FYI: the ham frequency's are, 160, 80, 60, 40, 20, 15, 10, 6 and 2 meters. There are other frequency's but those are the ones open to amateur radio operators. And some of those amateur frequency's are only open to different classes of operators. For example I only have a Technicians level ticket (License) so I can only use half of 10 meter, all of 6 and 2 meters. The others are only open to me at my level for CW (Morse code). When I get my next level ticket (General) I can use more of the aforementioned frequency spectrum.
« Last Edit: July 24, 2016, 08:48:30 AM by JohnyMac »
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Offline Nemo

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Re: Making Antenna's
« Reply #10 on: July 24, 2016, 10:41:43 AM »
New questions in block in Times New Roman typeface.


Quote from: JohnyMac on July 24, 2016, 08:45:57 AM
Response in bold.

@ Nemo:

Can you easily add X length to change frequencies? Easy is a relative term. It would be easier to just cut a new length.

So a new full length antennae wire is better than another X meter length and a wire nut?


How variable is frequency change? Sorry, I have only had 1 cup of coffee so far - I don't understand your question.

Question -pretty much same as above.  Add a wire nut and X length of wire for new freq.  Or more stuff needed.

Can you easily go to a second freq?  Go up and cover all between and to the 8th?  To the 42? Sure, if you change antenna's. Just a FYI: the ham frequency's are, 160, 80, 60, 40, 20, 15, 10, 6 and 2 meters.


So how many "channels" are there on (say 2 meter)  freq?  I am thinking 40 channels on CB type.

If there are 100 people on that freq, are they stepping on each other or different channels on that freq or ??.

Enough for now.

Nemo
« Last Edit: July 24, 2016, 10:53:06 AM by Nemo »
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Offline special-k

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Re: Making Antenna's
« Reply #11 on: July 24, 2016, 02:52:08 PM »
Nemo asked:
Quote
How variable is frequency change?

I'm pretty sure you're asking about the antenna's operating bandwidth.

Let's use CB as an example.  If you have 1:2 SWR (a scale to measure the antenna's efficiency at certain frequencies - 1:2 is the best you get on the scale) at the band's mid-point, the SWR will gradually increase (lose efficiency) as you go further away from the mid-point (in both directions).  The mid-point of the CB band is around channel 20 (27.205mHz).  For example, if a shitty, smaller 1/4 wave antenna is tuned for a 1:2 SWR* at channel 20, the SWR will likely be somewhere around 1:6 or 1:7 at channels 1 & 40.  With a larger antenna, let's say a 3/4 wave, the SWR will likely be somewhere around 1:3 or 1:4 at channels 1 (26.965mHz) & 40 (27.405mHz).  If you utilize the "freeband" channels above and below assigned 40 channels, this extra bandwidth comes in handy.

*Note:  A higher SWR equals more reflected transmit power (inefficiency).  A result of this reflected transmit power causes the transmitter to generate heat.  The higher the SWR, the faster the heat is generated during transmit. This heat, can eventually lead to the RF power transistor(s) (final transistor) burning out and needing to be replaced by a technician (or your self if you're good at such things).  Amateur operators generally consider an SWR better (lower) than 3:0 as usable.  CB and "freeband" operators like to keep it below 2:0, due to using a hodge-podge of equipment for purposes which it was not intended (never underestimate the power keyed by the dark side).

A 1:5 SWR = 4% reflected power
A 2:0 SWR = 11% reflected power
A 3:0 SWR = 25% reflected power
« Last Edit: July 24, 2016, 03:06:53 PM by special-k »
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Offline Nemo

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Re: Making Antenna's
« Reply #12 on: July 24, 2016, 07:39:13 PM »
OK, I have absolutely no idea what that all meant.

Please try again in dummie-speak.

Unless--  if I am on the CB and I go to channel 40 I get substantially less "usefulness" and range than on 20?

Nemo
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Offline special-k

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Re: Making Antenna's
« Reply #13 on: July 24, 2016, 10:29:55 PM »
Quote from: Nemo on July 24, 2016, 07:39:13 PM
OK, I have absolutely no idea what that all meant.

Please try again in dummie-speak.

And that's why I stopped going out of my way to explain anything to anyone...especially on the internet.  Sorry for my moment of weakness.  I'll try not to let it happen again.

 :coffeeNews:
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Offline JohnyMac

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Re: Making Antenna's
« Reply #14 on: July 25, 2016, 08:11:45 AM »
You are exactly right SK!  :bravo:

Looking at my Moxon antenna I am getting 1.1 SWR tuned at 146.000 Mhz (12 gauge wire cut to proper length). Which is the middle of the 2 meter frequency range.

@ Nemo
So how many "channels" are there on (say 2 meter)  freq? I am thinking 40 channels on CB type. The frequency range for 2 meter is 144.001 to 148.000 - So in essence there are 4,000 possible channels; however if you use a 5.0 Mhz step (Usual step going up op/ down the channel) that is 800 channels (4,000 / 5.0 = 800).

If there are 100 people on that freq, are they stepping on each other or different channels on that freq or ??. Well I guess if the people using the same channel are within "line of sight". The ham community unlike the CB community, are very courteous and will not step on someone already using that frequency.
« Last Edit: July 25, 2016, 12:29:47 PM by JohnyMac »
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Offline Nemo

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Re: Making Antenna's
« Reply #15 on: July 25, 2016, 09:39:09 AM »
Quote from: special-k on July 24, 2016, 10:29:55 PM
Quote from: Nemo on July 24, 2016, 07:39:13 PM
OK, I have absolutely no idea what that all meant.

Please try again in dummie-speak.

And that's why I stopped going out of my way to explain anything to anyone...especially on the internet.  Sorry for my moment of weakness.  I'll try not to let it happen again.

 :coffeeNews:

No biggie.  I am at least a bit interested in hamming and just trying to understand the general theory/operations/ops methods before I decide to spend a couple $$ on the idea of it.

Nemo
 
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Offline JohnyMac

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Re: Making Antenna's
« Reply #16 on: July 25, 2016, 09:59:15 AM »
Folks,
Here is a great article by NCSCOUT at Brush Beater on Moxon antennas. Worth your 10 minutes to read.
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Offline thatGuy

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Re: Making Antenna's
« Reply #17 on: July 25, 2016, 11:56:16 AM »
And now I've got another project, thanks for nothing JMac :P
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Offline JohnyMac

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Re: Making Antenna's
« Reply #18 on: July 25, 2016, 12:30:26 PM »
LOL TG!  :thumbsUp:
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Offline Nemo

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Re: Making Antenna's
« Reply #19 on: July 25, 2016, 01:19:18 PM »
Thats interesting.  And fairly understandable.  And now I will be spending the rest of the day mulling.  And I had several other plans!

Nemo
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gadget99

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Re: Making Antenna's
« Reply #20 on: July 28, 2016, 02:55:18 PM »
Just ordered a Roll-out J pole antenna from a guy in the states that sells them on ebay.

Was cheap enough. Wanted on from a seasoned antenna builder to use as the example for making my own.

Finally got the rest of the family to understand why I have been trying to convince them all to study for the foundation test. It took a major cell service outage for them to get it.
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Offline thatGuy

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Re: Making Antenna's
« Reply #21 on: July 28, 2016, 05:33:13 PM »
For those of you interested in making a roll out 2m antenna..

http://www.work-sat.com/Antennas_files/FONG-DBJ2.pdf
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Offline JohnyMac

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Re: Making Antenna's
« Reply #22 on: July 28, 2016, 09:17:47 PM »
Pretty cool TG! Now that is on my to-make list.
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Offline thatGuy

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Re: Making Antenna's
« Reply #23 on: July 28, 2016, 09:31:17 PM »
I'm gonna scrounge up the stuff for both tomorrow.
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gadget99

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Re: Making Antenna's
« Reply #24 on: July 29, 2016, 03:33:22 AM »
Thank you for posting that TG.
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