IW5EDI Simone - Ham-Radio

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The Handi-Tenna 70 cm Portable Antenna

Posted: 18 Apr 2020 04:56 PM PDT
http://www.iw5edi.com/ham-radio/3873...rtable-antenna



Here is a high-performance hand-held beam antenna that is easy to build and
guaranteed to improve your downlink from the LEO satellites over ANY rubber
duck or mobile whip. Like many satellite operators, I own an Arrow Antenna.
That antenna is a great performer, but sometimes it is impractical for me
to use itit is just too big. I sometimes can use the dual-band mobile whip
(mag mount) on my truck, but only on passes above 45 degrees (deaf below
that).










What I really wanted was a small hand-held antenna I could fit under/behind
the seat of my truck and just point out the window during a LEO pass. I
recently conducted some experiments on a 4-element beam antenna for mode J
downlink where I employed a folded-dipole feed to transform the feed
impedance up from 25 Ohms to 100 Ohmsmaking circular polarization matching
easy. I still had these parts laying around the garage (a.k.a. the R&D lab)
and

Design:
First, the design criteria:
1) It had to be flat enough to slide under my truck seat.
2) It had to be less than 18 overall length.
3) It had to cost less than $2.00 to build.

This first criterion rules out any sort of circular polarity scheme. The
second, allowing for a handle, limits the actual antenna length to about
12. This last goal, of course, is up to the builder, but easily
accomplished.

I designed this antenna as a very high-gain 3-element Yagi-Uda parasitic
array. It has almost 10 dBi of free-space gain (9.7 dBi free-space and 15
dBi at 5 elevation). This high gain is at the sacrifice of two key
variables: front-to-back ratio and feedpoint impedance. The E-Plane azimuth
plot at the right depicts the gain pattern. The minimal front-to-back
ratio, about 8:1, should not pose a problem unless you are in an area of
extremely high intermod interference. The nominal feedpoint impedance is a
very low 12.5 Ohms for a conventional dipole feed. Instead, a folded-dipole
feed element is used to transform the feedpoint impedance up to 50 Ohms
(4:1 ratio). Of course, this antenna is linearly polarized.

Construction:
The basic antenna is built around a boom of 1/2 PVC pipe cut to 18 length.
The antenna itself uses 12 of the boom length and I left 5 at the rear for
the handle and 1 at the front to attach a PVC capgives it that finished
look.A PVC coupling is used at the feedpoint to connect a couple of # 6-32
x 1/2 stainless steel bolts/nuts/washers to the coaxial cable (with crimpt
style ring terminals). All three elements are formed from 10 gauge wire
(insulated). The table below lists the dimensions and the sketch depicts
the layout. These dimensions are fairly critical and you should strive for
+/- 1/16 accuracy. All copper wire is used and the coax (with ring lugs)
connects directly to the driven element to minimize Ohmic losses.

El. Â*Â*Â* Â*Length Â*Â*Â* Â*Spacing
Ref Â*Â* Â*13.00 (33 cm) Â*Â* Â*0.00
DE Â*Â* Â*See Sketch Â*Â* Â*4.50 (11.5 cm)
D1 Â*Â* Â*12.00 (30.5 cm) Â*Â* Â*12.00 (30.5 cm)










Install the driven element (make sightly larger and trim for SWR) and the
director, but just try taping the reflector to the boom first. After
adjusting the driven element for best SWR at 436.8 mHz, you can move the
reflector slightly to get the SWR perfect. I used glue to hold the
reflector and director in place and then spray painted the whole assembly a
traditional aluminum color for a nice finished look. After all, if you are
going to wave this thing around in the air and point it up in the sky, you
want it to look profesional for the dumbfounded onlookers

I used RG-8X and not the more common RG-58. For an equivalent 10 (2.5 m) of
coax, RG-58 has 1.2 dB loss while RG-8X has only 0.8 dB loss. With LEO
satellites, every fraction of a dB counts.











Performance:
As the bird (AO-27) comes over the horizon, I hear the tell-tale signs of
FM quieting. By 5 degrees above the horizon I can make out about 50 percent
of the in-and-out audio. By 10 degrees above the horizon, the signal is
strong and by 15 degrees it is full quieting. In terms of comparison, I get
full-quieting at about 5 degrees with my Arrow Antenna.

I can also confirm (again) the polarization of choice for AO-27 is
vertical. At times, a slight tilt of the antenna improves reception, but
placing it horizontal completely obscures the signal.

This antenna makes a nice companion to the 2 meter vertical and can be used
mobile, like I use it, or as a fairly light and compact backpacking setup.




Article by K5OE originally available at
members.aol.com/k5oejerry/handi-tenna.htm

The post The Handi-Tenna 70 cm Portable Antenna appeared first on IW5EDI
Simone - Ham-Radio.


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A multi-band super mini loop antenna

Posted: 18 Apr 2020 04:51 PM PDT
http://www.iw5edi.com/ham-radio/3870...i-loop-antenna



Heres how to make the Super antenna.










To build this antenna you need a lot that is at least 100 feet across.
(This can be on a diagonal).

Antenna covers all bands 80-10 meters + 30, 17, 12 meter WARC Bands

This antenna works as a Full Wave Loop on 80 Meters and also works as a 2
wavelength open loop or Bi-Square on the 40 Meter band.
The gain is around 4 dBd on 40 mtrs, but it will seem much higher due to
the very low angle, radiation pattern. Any antenna tuned for 80 Meters
should also work on 20 and 10 meters as well. If an antenna works on 40 it
should work on 15 as well. A tuner will probably be needed for 10, 18 and
24 MHz Band operations.

The loop is an inverted vertical triangle with the base along the top and
what would be the apex hanging down. Or it could be erected horizontally if
needed.

The feed point at the bottom uses a 3:1 or 4:1 balun and is then fed with
any needed length of 50 ohm coax. The top center is broken with an
insulator and has a 29 feet 10 inch length of 450 ohm ladder line connected
across the insulator.
IMPORTANT The 450 ohm ladder line is shorted across at the bottom end.

Here is how I calculated the loop size.
Dimensions
One wavelength at say 7.25 MHz = 1005/7.25 = 138.62 or 138 feet 7.5 inches.
If this length is doubled and used on 80 meters as a loop Then Freq(for a
loop) = 1005/(2 x 138.62) = 3.625 MHz.

The 1/4 wave stub = 246 multiplied by (Velocity Factor of your type of
ladder line) /7.25 = about 32 feet.

Ladder line / twin lead velocity factors vary by brand, type, insulation,
etc.
The best method is to use a grid dip oscillator or antenna analyzer to
measure the resonant frequency of the 1/4 wave matching stub during
construction, rather than by just using the mathematical formula to
determine the length.


The perimeter of the 80 meter loop for 3.625 MHz = 277.24 (2 x 29’ 10�)[2
x 29.86 feet = the length of both sides of the wire in the ladder line] =
217.52 ft. Let’s call it 217.5 feet.

If the top horizontal span is made 99.5 feet overall and the legs 59 feet
each then the balun will hang about 30.5 ft below the top center insulator.
The 29’ 10� ladder line can have its bottom shorted end tied to the top
of the balun with a short length of fishing line, weed eater line, string,
or cord etc.

On 40 meters the ladder line stub automatically acts as a switch and opens
the connection across the insulator so the antenna works as 2 one wave
length loops fed in phase.

This antenna is a high performance, full size, full wave, 80m loop antenna.
On 40m it is a 2 wave length open loop or Bi-Square.
The stub in the top leg of the antenna opens the loop when operating on 40m
and selected other bands.
This improves the antennas radiation pattern.
Its gain is around 4dB, but it will seem a lot higher due to its excellent,
low angle, radiation pattern.

The 50 Ohm coax from the balun to transmatch is not critical but
recommended to be 1/2 wave length.
( 99 Feet of RG-8X )

This antenna could also be configured as a 54’ 4.5� square on a horizontal
plane. The 217.5 ft loop can be pulled into almost any shape but the bigger
the “aperture� enclosed area the better it will work.

I have NOT tried this experimental design yet. I believe my calculations
are correct and should work.

I have heard rumors that something similar to this
Multi-Band loop antenna is available commercially
as a Super Loop from R a d i o W o r k s.



The antenna has been built and tested by Don / K8THU.

Here are excerpts from emails I got from Don in Nov, 2005

Hi Ace,
The stub needed to be longer than you quoted.
{Page info has been updated to longer stub}
The other measurements are exactly as you stated. The antenna is resonant
at 7.21 so I could shorten it slightly but have not done so. I just was on
20 and worked N. Ireland and France again both with 5/8 reports. I am using
just 100 watts with my Kenwood 570 and the internal tuner. Locally on
ground wave on 75 meters I am getting 20 over 9 reports on distances about
300+ miles.
Don, K8THU

Hi Ace,
Ok, on Saturday we removed the 1/4 wave stub and found it was too short so
we changed it and then pruned it until the stub was resonant at 7.25. I did
not alter the loop size other than the stub length. Then we reassembled the
whole antenna and found with the extra stub length the overall antenna
resonant frequency was 7.21 Mhz. so I left it there for now and began SWR
testing. The SWR readings are after the stub lengthening. Ladder line is 14
ga. stranded and the other line is also 14 ga. stranded and insulated
(thnn?).

VSWR Measurement Results follow:





3.995 Mhz / SWR 1.1 to 1
3.751 Mhz / SWR 2 to 1
7.164 Mhz / SWR 1.1 to 1
7.290 Mhz / SWR 1.2 to 1
14.151 Mhz / SWR 1.3 to 1
14.348 Mhz / SWR 1.7 to 1
21.250 Mhz / SWR 2 to 1
21.441 Mhz / SWR 2.5 to 1
24.932 Mhz / SWR 3.5 to 1
24.987 Mhz / cant load
28.331 Mhz / SWR 3 to 1
29.650 Mhz / cant load

Usually I cant load on 10 meters.
40 and 20 are really quite good. Even 15 isnt too bad.
Don, K8THU

End of excerpts from emails.




Article by W2HT originally available at www.bloomington.in.us/~wh2t/Super
Loop Antenna.htm

The post A multi-band super mini loop antenna appeared first on IW5EDI
Simone - Ham-Radio.


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2 meter Cubical Quad Antenna

Posted: 18 Apr 2020 04:48 PM PDT
http://www.iw5edi.com/ham-radio/3866...l-quad-antenna



This antenna does not need a 75 Ohm transformer as quads do at lower
frequencies. Any length of a good quality RG58X will suffice as the primary
feedline.








Connect to station with any length of good 50 ohm coax and PL-259
connectors and one barrel connector to couple the feed lines.




This antenna can be tuned with almost any light duty rotators-wind load is
small, antenna is light.








The support mast should be wood and would be a good practice to have it at
least 3 feet long to get the antenna above the rotator.




Never use metal for the boom, mast or spreaders.




The configuration shown is for vertical polarization if you want horizontal
polarization feed driven loop at the bottom instead of the side.Â*

The post 2 meter Cubical Quad Antenna appeared first on IW5EDI Simone -
Ham-Radio.


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An easy dual band VHF UHF Antenna

Posted: 18 Apr 2020 04:37 PM PDT
http://www.iw5edi.com/ham-radio/3861...hf-uhf-antenna







This article taken from QST September 1994 is about a vertical dual-bandÂ*
antenna for 144 and 430 MHz made with a TV twin lead and coax cable.




Download PDF







The post An easy dual band VHF UHF Antenna appeared first on IW5EDI Simone
- Ham-Radio.


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Cheap Yagi Antennas for VHF/UHF

Posted: 18 Apr 2020 04:32 PM PDT
http://www.iw5edi.com/ham-radio/3854...as-for-vhf-uhf




Editors notes:Â*The antennas described in this article were built as the
result of several discussions between Kent and a Cuban radio operator.
While there are plenty of high performance antenna designs, most of the
parts required to build them are not available in Cuba. There just isnt an
EPO or Radio Shack available in Cuba. Kent accepted this as a challenge to
design a really good antenna that could be built with little more than
ground wire, coax and a wooden boom. Using the latest antenna design
software, he has developed several variations for 144 thru 1296 MHz.
Apparently, the designs work very well Kent entered the 432 MHz version in
a recent antenna contest and lost by 0.2 dB to a Midwest ham who had copied
his design. Though disappointed in losing, it did prove to Kent that the
antennas can be easily replicated with consistant performance.]









If youre planning to build an EME array, dont use these antennas. But, if
you want to put together a Rover station with less than $500 in the
antennas or just want a good antenna for the home, read on.

These antennas are relatively small, easily constructed from common
materials/tools and have surprising performance. The feed method is greatly
simpified by directly soldering the coax to the driven element. No baluns
or gamma matches are used in this design. This simplified feed uses the
structure of the antenna itself for impedance matching. The spacing of the
director and reflector elements from the driven element directly affects
the feed point impedance of the antenna. So, the design starts with the
feed (driven element) and the elements are built around it. Typically, a
high gain antenna is designed in the computer, then you try to come up with
a matching arrangement for a 31.9 Ohm feed! For the cost about 0.5 dB of
gain, these antennas make some design compromises for the feed impedance,
use an asymmetrical feed and make trade offs for a very clean pattern. But,
they allow simple measurements, have wide bandwidth, the ability to grow
with the same element spacing AND you can build these antennas for $5!!!!










The booms used for these antennas is 1/2 X 3/4 wood. The elements have been
made from silicon bronze welding rod, aluminum rod, hobby tubing and solid
ground wire with no change in performance. Since you want to be able to
solder to the driven element, silicon bronze welding rod, hobby tubing and
#10 or #12 solid copper wire have been used and work fine. A drop of Super
Glue, epoxy or RTV is used to hold the elements in place. A good coat of
Polyurethane should be applied to the wooden boom to protect it from the
weather. A polyurethane varnished 902 MHz version has been in the air for a
year now with little deterioration in performance.

And now for the antenna designs. These antennas have been carefully
designed to have the highest dBs/Dollar ratio of anything around They were
designed with YagiMax, tweaked using NEC and the driven elements
experimentally determined on the antenna range. The driven element design
is the same for all frequencies except for the length (L) and separation
(H). See the drawing below for details on the driven element. All
dimensions are in inches.








Antenna Designs By Band:




144 MHz. This antenna is peaked for 144.2 MHz but performance is still good
at 146.52 (emergency use only!). Driven element dimensions are L = 38.5 and
H = 1.0 Elements are 1/8 diameter.




144 MHzREFDED1D2D3D43 EleLength
Spacg41.00
0.00
8.5037.00
20.004 EleLength
Spacg42.00
0.00
8.5037.50
19.2533.00
40.506 EleLength
Spacg40.50
0.00
7.5037.50
16.5036.50
34.0036.50
52.0032.75
70.00





222 MHz. This antenna is peaked for 222.1 MHz but performance barely
changes at 223.5 MHz. Driven element dimensions are L = 24.5 and H = 1.0
Elements are 3/16 diameter.



222 MHzREFDED1D2D3D43 EleLength
Spacg26.00
0.00
5.5023.75
13.504 EleLength
Spacg26.25
0.00
5.0024.10
11.7522.00
23.506 EleLength
Spacg26.25
0.00
5.0024.10
10.7523.50
22.0023.50
33.7521.00
45.50






432 MHz. This antenna is peaked for 432.1 MHz. At this frequency, this
antenna is getting very practical and easy to build. Driven element
dimensions are L = 13.0 and H = 3/8 Elements are 1/8 diameter.



432MHzREFDED1D2D3D4D5D6D7D8D96 EleLength
Spacg13.50
0.00
2.5012.50
5.5012.00
11.2512.00
17.5011.00
24.008 EleLength
Spacg13.50
0.00
2.5012.50
5.5012.00
11.2512.00
17.5012.00
24.0012.00
30.7511.25
38.0011 EleLength
Spacg13.50
0.00
2.5012.50
5.5012.00
11.2512.00
17.5012.00
24.0012.00
30.7512.00
38.0011.75
45.5011.75
53.0011.00
59.50






902/903 MHz. This was the first antenna I built using the antenna to
control the driven element impedance. The 2 1/2 length has proven
practical, so I havent built any other versions. Driven element dimensions
are L = 5.7 and H = 1/2 Elements are 1/8 diameter.



902/3 MHzREFDED1D2D3D4D5D6D7D810 EleLength
Spacg6.20
0.00
2.405.60
3.905.50
5.805.50
9.005.40
12.405.30
17.405.20
22.405.10
27.605.10
33.00






1296 MHz. This antenna is the veteran of several Grid Peditions but I have
yet to actually measure the gain. Dimensions must be followed with great
care. The driven element is small enough to allow 0.141 semi-rigid coax to
be used instead of RG-58. Silicon Bronze welding rod was used for the
elements but any material can be used. Driven element dimensions are L =
4.0 and H = 1/2 Elements are 1/8 diameter.



1296 MHzREFDED1D2D3D4D5D6D7D810 EleLength
Spacg4.30
0.00
1.703.90
2.803.80
4.003.75
6.403.75
8.703.65
12.203.60
15.603.60
19.303.50
23.00






OTHER VERSIONS

421.25 MHz ATV. 421 MHz Vestigial Sideband video is popular in North Texas
for receiving the FM video repeaters. The driven element for these antennas
is designed for an impedance of 75 ohms. So RG-59, or an `F adapter to
RG-6, can be directly connected to a cable TV converter/Cable Ready TV on
channel 57. Driven element dimensions are L = 13.0 and H = 1/2 Elements are
1/8 diameter. Spacing is the same for all versions.



421 MHz ATVREFDED1D2D3D4D5D6D7D8D96 EleLength14.0012.5012.2512.2511.008
EleLength14.0012.5012.2512.2512.0012.0011.2511 EleLength
Spacg14.00
0.00
3.0012.50
6.5012.25
12.2512.25
17.7512.00
24.5012.00
30.5012.00
36.0011.75
43.0011.75
50.2511.50
57.25






450 MHz FM. Yea, I understand its FM, but sometimes a newcomber needs a
cheap antenna to get into a repeater or give you a simplex QSO during a
contest. Driven element dimensions are L = 12.0 and H = 3/8 Elements are
1/8 diameter. Spacing is the same for all versions.



450 MHz FMREFDED1D2D3D46 EleLength
Spacg13.00
0.00
2.5012.10
5.5011.75
11.0011.75
18.0010.75
28.50






435 MHz AMSAT. The larger versions have not been fully tested and I
appreciate the help and motivation from KA9LNV for these antennas. Updates
and performance evaluations are planned for a later edition of the AMSAT
Journal. A high Front-to-Back ratio was the major design consideration for
all versions. The computer predicts 30 dB F/B for the 6 element and over 40
dB for the others. NEC predicts 11.2, 12.6, 13.5 and 13.8 dBi for the 6, 8,
10 and 11 element respectively. Using 3/4 square wood makes it easy to
build two antennas on the same boom for cross- polarized operation. Offset
the two antennas 6 1/2 and feed in phase for Circular Polarization. Or,
just build one antenna for portable operation. Driven element dimensions
are L = 13.0 and H = 1/2 Elements are 1/8 diameter. Spacing is the same for
all versions.



435 MHz AMSATREFDED1D2D3D4D5D6D7D8D96 EleLength13.4012.4012.0012.0011.008
EleLength13.4012.4012.0012.0012.0012.0011.1010
EleLength13.4012.4012.0012.0012.0012.0011.7511.751 1.1011 EleLength
Spacg13.40
0.00
2.5012.40
5.5012.00
11.2512.00
17.5012.00
24.0012.00
30.5011.75
37.7511.75
45.0011.75
52.0011.10
59.50




by Kent Britain, WA5VJB (edited by John Maca, AB5SS)

The post Cheap Yagi Antennas for VHF/UHF appeared first on IW5EDI Simone -
Ham-Radio.


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A 160 meter antenna for small lot

Posted: 18 Apr 2020 04:26 PM PDT
http://www.iw5edi.com/ham-radio/3848...-for-small-lot



My back fence is 50 ft from the rear of the house and not enough room on
the property for 80 meter wire antenna must less a 160 meter one, and this
to work great with the sloper wire attached to a fence, I also use
monofilament (non-conductive) line like fishing or Weed Eater line as
support for the PVC tubing on the top of my house.




I have used with 100 watts and use with 1500 watts with the amp and at this
time melt down…!!




Cut the length of the sloper to the freq. where you want to operate at.








My sloper is approx. 68.5 ft. at 1853 with a 1:2 to 1:3 +/- 25 to 35 kc
with no tuner, this is better than my ½ wave dipole, looks like the sloper
will vary to each installation…..I also tuned the ground wire with an 18 uh
roller inductor that allowed me to move +/- the center frequency, didnt’t
try but a fixed coil with a switch possibly would work over wider range




I’m in process building another one with a remote switch to select coil
windings to move up and down 160 or possibly even 80/75 meters, more at
eleven.




If anyone is going to try one, I have worked out a system on winding the
wire on the PVC pipe using a variable drill…








NOTE: The last couple that were built I used 2� PVC pipe with the same 70
Ft. of wire wound with the 1/2 spacing….just made the pig tail longer by 7�
(Just tune to operating frequency.) the 2� PVC is better for mechanical
stability…..




CAUTION: IF YOU MOUNT THE ANTENNA MECHANICALLY COUPLED TO A STEEL VENT PIPE
AS SHOW IN “THE PICTURE DON’T USE THE CRAPER WHEN IT’S STORMING OUTSIDE…!�




73’




Troy




K5CBL

The post A 160 meter antenna for small lot appeared first on IW5EDI Simone
- Ham-Radio.


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A short dipole for 80 meters

Posted: 18 Apr 2020 04:22 PM PDT
http://www.iw5edi.com/ham-radio/3845...-for-80-meters



The antenna above has been described by Nadisha, 4S7NR and may be of
interest to anyone wishing to get on 80M (3.5MHz) that have limited space
available.



short dipole for 80m




L1 is 12 feet. L2 also is 12 feet and the overall length is 48 feet.




The two loading coils are described as 67.83uH and can consist of 104 turns
of insulated wire, wound over 3.5 inches. The coil diameter is not stated
however. Maybe it will be a case for experimentation here.

The post A short dipole for 80 meters appeared first on IW5EDI Simone -
Ham-Radio.