6m Antenna Dimensions

Six Meter Wire Antennas

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Six Meter CW/SSB

Center Frequency:  50.100 Mhz 147.86 Mhz 3rd Harmonic
Halfwave in space is:   9.82 feet  6.68 coax| 8.05 twinlead
Quarterwave in space is:  4.91 feet  3.34 coax| 4.03 twinlead

Quarterwave Vertical is:  4.67 feet  5.50 foot ground radials
Five Eights wave Vertical is: 12.04 feet  4.67 foot ground plane
Three Quarter wave Vertical: 14.49 feet  2.34 foot eighthwave

Halfwave Dipole/Vertical is:  9.34 feet  4.67 one side.
Halfwave Reflector is:   9.81 feet  8.92 for Director
Low Mount Halfwave is:   9.14 feet  4.57 one side.
Halfwave Folded Dipole is:  9.22 feet  4.61 one side.
Halfwave Inverted V is:   9.68 feet  4.84 one side.
Colinear Array is:  19.16 feet  9.58 one side.
Extended Double Zepp is: 24.07 feet 12.04 one side.

Fullwave Quad Loop is:  20.36 feet  5.09 one side.
Reflector|Director:  21.38|19.44  5.34| 4.86 one side.
Fullwave Delta Loop is:  20.36 feet  6.79 one side.
Reflector|Director:  21.38|19.44  7.13| 6.48 one side.

Waves 1:  19.16 |1.5:  28.98 |2:  38.80 |2.5:  48.62 |3:  58.44 |4 :  78.08
Waves 5:  97.72 |6.0: 117.37 |7: 137.01 |8.0: 156.65 |9: 176.29 |10: 195.93

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Six Meter FM

Center Frequency:  52.525 Mhz 155.01 Mhz 3rd Harmonic
Halfwave in space is:   9.37 feet  6.37 coax| 7.68 twinlead
Quarterwave in space is:  4.68 feet  3.18 coax| 3.84 twinlead

Quarterwave Vertical is:  4.46 feet  5.25 foot ground radials
Five Eights wave Vertical is: 11.48 feet  4.46 foot ground plane
Three Quarter wave Vertical: 13.82 feet  2.23 foot eighthwave

Halfwave Dipole/Vertical is:  8.91 feet  4.46 one side.
Halfwave Reflector is:   9.36 feet  8.51 for Director
Low Mount Halfwave is:   8.72 feet  4.36 one side.
Halfwave Folded Dipole is:  8.80 feet  4.40 one side.
Halfwave Inverted V is:   9.23 feet  4.62 one side.
Colinear Array is:  18.28 feet  9.14 one side.
Extended Double Zepp is: 22.96 feet 11.48 one side.

Fullwave Quad Loop is:  19.42 feet  4.85 one side.
Reflector|Director:  20.39|18.55  5.10| 4.64 one side.
Fullwave Delta Loop is:  19.42 feet  6.47 one side.
Reflector|Director:  20.39|18.55  6.80| 6.18 one side.

Waves 1:  18.28 |1.5:  27.64 |2:  37.01 |2.5:  46.38 |3:  55.74 |4 :  74.48
Waves 5:  93.21 |6.0: 111.95 |7: 130.68 |8.0: 149.41 |9: 168.15 |10: 186.88

Note: At Six meters the diameter of elements in terms of wavelength starts to become large, even with heavy wire like 10 gauge. With tubing elements, an additional shortening factor starts to become important. As elements get fat, the resonant frequency goes down for a given length. This is not a problem on the lower frequencies where even one inch tubing is still small diameter relative to wavelength, but at six meters and above it starts to become more and more significant.

80m NVIS Antenna

Built an 80m inverted V and based on VE3RIPs modelling stuck the apex up at 30'.    Found some old wire that I pulled down a few tears ago.  It was my 80 dipole ,  down low too!    The dimensions were more or less what I was looking for.  Put the antenna up just behind the house.  To my pleasant surprise it was optimized at 3.750 MHz good for a 1:1 match.   I could go +/- 500 kHZ and the VSWR remained below 2:1.   

The IFL from the Antenna to the SW was about 60'.   I couldn't resist testing the cable for loss before I hung an antenna off it .....

So the loss at 3.2 MHz was 1.7 / 2 = 0.85 db. 

The IFL going from the 4X1 SW to the Rack ...

From the rack where the antennas terminate in the house to the 4X1 coaxial sw just up behind the house the loss is 5.1 / 2 = 2.55 db @ 4.8 MHz.  So using the NanoVNA the cumulative loss to the 80m Inverted V is somewhere a little over 3 db.

Swept the Antenna from the rack after it was up....














Added a 20' chunks of rg59 and swept again...

The added cable changed the sweet spot slightly. 

And the overall return loss @ 1 MHz ( worst VSWR spot )

The return loss came in a 2.28 db so its 2.28 / 2 = 1.15 db of loss.  This is quite a bit different  then the two cables swept individually which yielded a 3 db loss. 

Its probable safe to say the cable loss is somewhere between 1 and 3 db at 3.750 MHz. 

NanoVNA Antenna Testing - VSWR and Cable Loss

 I have some time on my hands so I finally got up to speed on the NanaoVNA.  It was actually pretty easy to figure out and quite allot of bang for the BUC.

The initial test will be to go through all my Antennas from 160m to 70cm and get VSWR measurements in the pass band they are dedicated too.   Initial setup is a 20' chunk of RG59 between the Nano and my rack where all the antennas terminate.   Then I will move to the rack and test again just to see if there is much of a difference.

Band     Antenna Type             Initial Test                2nd test @rack with 1'Cable
160m   Inv  L/8 radials            1.884 / 1.1                 1.1.807 / 1.1
80m     Inv L/8 radials             3.819 / 1.1                 3.5 / 1.1
40m     1/4 Vert/8 Radials        7.0 / 1.1                    7.3 / 1.1
30m     1/4 Vert/8 Radials        10.5/ 1.1                   10.15 / 1
20m     1/4 Vert/8 Radials        14.0 1.1                    14.1 / 1.1
17m     1/4 Vert/8 Radials        18.0 / 1.2                  18.3 /1.0
15m     Fan Dipole                   21.0 / 1.9                  21.5 / 1.9
10m     Fan Dipole                   28.0 / 1.5                  28.9 / 1.4
6m       Fan Dipole                   51.6 / 1.1                  51.1 / 3.0
2m       5/8 Vert                        146.7 / 1.1                146.2 / 1.0
2m       Vert*                            145.3 / 1.2                144.6 / 1.1
70 cm  Vert*                            430.0 1 / 1.0             431.1 / 1.0


* some sort of commercial dual band vertical at the top of the hill


To measure cable loss and length ideally you would have an open cable... all reflected back.  Plan B,  choose a freq with an SWR > 3 the higher the better!   Best for measuring length as well as cable loss...not perfect but a good ballpark.

Band                                    worse swr             cable loss
160m   Inv  L/8 radials       1.136 / 4.3                 2db
80m     Inv  L/8 radials       2.5  / 3.0                    3db
40m     Inv  L/8 radials       3.5 / 3.1                     2.8db

The 160m inv l works very good on 6m

The IFL is about 500' of LDF4.  The worse SWR close to 50MHz was @ 66.963 MHz and was 2.6.  I ran the test here and the loss measured was 3.5 db.

LDF4 is listed at 50.0 MHz 0.46 db / 100 ft and at 85 MHz its 0.60 db / 100ft.  As you can see the Nano measurement is pretty close to theroretical. 

The Only One

Its 2:45 pm est and I am receiving IK2YWC on 160m FT8...the only North American station hearing him!

Magic Antenna - 160m Inverted L - MMANA on different frequencies.

Using the antenna tuner in my Yaesu FT450d I am able to successfully load it on 40, 30, 20, 17, 15, 12, 10 and 6m.   The antenna works quite well in some cases better then the 1/4 verts  and I totall credit it sitting on a 120' tower ...its really a very steep gravel hill! 

40 Meters

Actual VSWR no tuner 3.6:1

Ran MMANA for resonance ....

8.3 MHz

7.1 MHz

SWR is 49:1 ,   in reality its 3.6:1 but the modelling software has it resoant not too much higher in freq.

On 30 M

Actual VSWR no tuner 3.1:1

The software models it at 18.7:1 at 10.1 MHz
















Ran MMANA for resonance but it found it around 19 MHz with a 50:1 VSWR..



On 20 M

Actual VSWR no tuner 2.1:1

The software models it at 17.2:1 at 10.1 MHz
















Ran MMANA for resonance but it found it around 15.1  MHz with a 3:1 VSWR..

On 17 M

Actual VSWR no tuner 2.1:1

The software models it at 4.1:1  at 18.1 MHz

On 15 M

Actual VSWR no tuner 1.5:1

The software models it at 6:1  at 21.1 MHz

On 10 M

Actual VSWR 28 no tuner 1.4:1

The software models it at  4.8 :1 at 28.0 MHz

On 6 M

Actual VSWR 50 no tuner 1.5:1

The software models it at  6.3 :1  at 50 MHz

MMANA Antenna Modeling - My 160m inverted L

Had some quiet time over the holidays so I have successfully used MMANA Software to model my 160m Inverted L.   I can see that there is a huge advantage to building ,  optimizing and using an Antenna before building the model.  MMANA is fantastic but finicky for the casual user,  More then anything its just takes a bit of familiarity to be successful at it. 

So  here is my antenna.  The radials all slope away with the exception of the one that runs along the X axis ....more or less straight North.   The radiating element more or less runs along this axis too!














In reality the radials have not been tuned each one is 45.7 m long.  The program was told to optimize for VSWR and below is the recommendations for the radials. 


















The vertical component or if you prefer radiator started at 45.7 m.  Took at least a meter off tuning the antenna so its really very close to 44.7 m.   

The optimized length is 44.48 m. 

Performance...optimized to the above dimensions...

The data was all done using free space.   The radials are at a around are around -30 degrees off  level all but one sloping away from the antenna.   The antenna is sitting at the apex of a gravel hill and is connected via 500' of LDF4. 

Here is the same antenna not optimized .....the real deal.  Each radial is 45.7 m and the radiator is close to 44.7 m. 

The VSWR is quite a bit different.  In reality its around 1.5 to 2.0 at 1.85 MHz but the program does not have 500' of LDF4 connected to the antenna!   So the numbers are close enough to the reality to believe the model,  That being said I will have to try tuning certain radials to optimize performance.

BELOW is the model built with the actual dimensions.....

At 1.85 MHz ...

At resonance ...

At 1.85 MHz

Here is where the antenna is actually resonant....

At 1.85 MHz

At resonance ...

I really did find this antenna to be resonant 100 KHz lower in frequency around 1.7 MHz.   I brought it much closer to 1.8 MHz taking a meter or so off the radiator but did not touch the radials.   It truly is quite dramatic what a difference the modem show in  SOME of the radials to get it to resonate at 1.8 MHz. 

Regardless of the resonance one thing that remains constant is the deep null at 90 and 270 degrees  10 to 15 db is HUGE!!!!!   Planning on playing around with the model moving the AZ of the radiator ....this is something I can do in the real world too but before I do anything I would like to try tuning 4 of the radials particularly the ones that run east west. 

Late fall antenna tweaking...

Wasn't real happy with a few of my antennas so I decided to attempt to improve the match. 

20m 1/4 Vert ...just behind the house. 

Took some length off the Vertical element SWR is now

Freq        VSWR
14.0          1:1
14.5          1:1
14.1          1:1
14.15        1:1
14.2          1:2
14.25        1.3
14.3          1.4

Super happy with that ,  worked an RU this morning CW.  Tried to work a guy in Bulgaria but wasn't successful switched to the 160m vert at the top of the hill and was successful. 

80m inverted L ( 1/4 vert ) 

Took a wee bit off this antenna too but its not nearly as broadband as the 20m antenna.  Suspect a tweak of the radials might help that out but its not happening until the snow goes which may be April.

Freq      VSWR
3.45        1.9:1
3.5          1.45:1
3.55        1.4:1
3.6          1.5:1
3.65        1.8:1
3.7          2.2:1

So yeah,  I am mostly CW and FT8 on 80m so its great there however go up and not so much.   Think I may try a low dipole cut to 3750 for SSB. 

160m inverted L ( 1/4 vert )

Same this goes took a foot off the vert radiator

Freq        VSWR
1.7            2.1 :1
1.75          1.4:1
1.8            1.4:1
1.85          1.7:1
1.9            2.1:1

Again great for CW and FT8 but not so much for SSB.   This is my " magic " antenna that loads up on 40,  30,  20,  17, 15,  12, 10, 6 meters with just the antenna tuner in the radio!     I have had success on 6m meteor scatter running 100 watts into this antenna.   A while back ( in the blog somewhere ) I compared the 20m 1/4 behind the house with the 160m L up the hill and the big guy performed better! 


Here is how the 160m loads ...no antenna tuner!

Freq   VSWR
80m NO WAY ,  does not work
40m    3.6:1
30m    3:1:1
20m    2:1:1
17m    2.1:1
15m    1.5:1
12m    1.6:1
10m ( 28 MHz ) 1.4:1
10m ( 29 MHz ) 2.1:1
6m    (50 MHz ) 1.5:1
6m    (51 MHZ ) 1.3:1
6m    ( 52 MHz ) 2.1:1

From 50.6 to 50.9 MHz its a dead flat 1:1 VSWR...go figure

I use the 160 antenna when work FT8 remotely ,   no antenna switching required and I can flip around between bands super easy.