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IW5EDI Simone – Ham-Radio

DL2HCB Multiband Delta Loop

Posted in HF Antennas 2 Comments

After a Qth change last year, I was fortunate to get permission for an outside antenna. The new antenna was built with the following considerations in mind.

At least 10 – 20m coverage

Open wire feed to simplify matching the various impedances

Loop design, because it is less sensitive to nearby objects and it requires less real estate, considering the length of the antenna. Broadside radiation on all bands as the antenna is running N/S and I wanted most of the power into E/W direction.

While studying “Cubical Quad Antennas” by Orr/W6SAI & Cowan/W2LX, I notices the mini-X-Q (eXtended Quad) which is basically a 3/2 wave open loop with 3 db gain. Because of limited space and height 928ft), I have built the 10m mini-X-Q and modified it into a delta.

The next step was to convert it into a multiband antenna, giving comparable results to a mono-band loop or dipole. At the open end of the loop a 1/4 wave shorted stub for 28Mhz was added. The stub and the feed line is made of 450 ohm ladder line. The stub opens the loop on 28Mhz, on all other frequencies the antenna is working as a closed loop.

The antenna has been in use for a few weeks now and produced solid signals within Europe, nevertheless DX has also been worked e.g 20m with Dave FY/DJ0PJ as one of the first QSOs, 2 way QRP of course. I have also used the antenna on 30m and 40m to contact other Euopean stations.

72/3 Bert DL2HCB

A Practical Antenna for 160 Metres

Posted in HF Antennas 1 Comment

Original article published by G3YCC

“This aerial is one I have used for top band (160 metres) – it was suggested to me by Alan G4ERZ, also of Hull.

It consists of 140 feet of insulated wire, the first half of which (70 feet) is space wound on an insulated tube.

  • I used glass fibre tubing which was to hand, but PVC may be used also.
  • My tube is 1 1/2 inches in diameter and about 5 feet 6 inches long.
  • The turns are about 0.5 inches apart.
  • The other 70 feet of wire acts as a loading wire and slope down from the top of the coil to near ground level.
  • The system is coax fed to the base of the coil, with the shield or braiding going to earth.
Continue reading→

80M Vertical Antenna with Capacitance Hat

Posted in HF Antennas 1 Comment

Design Criteria:

  • Simple wire antenna;
  • Cheap to make, using readily available materials;
  • Low angle radiation, with rejection of high angle signals;
  • Wide bandwidth, with resonance at the 80M DX window (3.790-3.800 MHz); and
  • Maximum height is 40 feet (limitation due to treeheight).

Design:

Since the use of a full ¼-wave vertical was out of the question because of space reasons, it was decided to use a smaller vertical, and load the top portion of the antenna with a capacitance hat. Based on modeling results, the following dimensions satisfied the design requirements:

Wire Lengths of Antenna Described for 3.800 Mhz

Wire Number     Length    Included Angle
    1                      11.89 m       (39') N/A
    2                      5.84 m        (19'-2") 29º
    3                      5.84 m         (19'-2") 29º

The nylon lines connecting wires #2 and #3 to the ground are 6.58 m (21’-7”) from the
vertical wire #1. This makes the determining the angle moot, and simplifies installation.

Model:

The model was made in MMANA, with 200 segments per wire. Real ground was modeled, ith a dielectric strength of 1.0 and an earth conductivity of 1.0 mS/m – very poor
conductivity. The model included 3 radials, approximately 5 m long. results of the model are shown attached.

 Results:

After erecting the antenna, and driving in a 12mm copper ground rod, measurements were taken prior to attachment of radials. The resistance was very high. Radials were attached, and the measurements were retaken using a MFJ-259 SWR Analyzer. The results showed resonance at 3.720 MHz, with no tuning required. The 1.5:1 bandwidth was 3.620-3.82 MHz, or approximately 200 KHz. The band width definition of 1.5:1 was chosen to allow the use of an amplifier.

After a period of time it was noticed that the SWR crept up from 1:1 at 3.720 to approximately 1.3:1 at 3.825 MHz, with no changes to the antenna. Examining the change with an MFJ-259 SWR Analyser, it was found that the antenna had reduced capacitance, resulting in a shift in the resonance, and an increase in SWR. Since the antenna was hung rom a tree, and the antenna was erected when leaves were still on the trees, it is suspected that the presence of leaves increased the effective capacitance of the antenna.
When the leaves fell for the winter, the capacitace effect was reduced, and the SWR increased. Also, the moisture of the ground in August when the antenna was erected was ery low. In November, substantial rain occurred, resulting in better ground conductivity.

This had the effect of increasing the resonance, and broadening the 1.5:1 SWR range. So it is expected that the curves will return to the original SWR once leaves appear on the trees  again. The SWR curves of the antenna are on picture 3.

On-the-air results were gratifying. Using an Icom-756Pro, and AL-80A, running 500 watts, I was able to work Sweden, England, Germany, Ukraine, Belarus, Russia, Bulgaria, Slovenia, Poland, Hungary, and other Europeans on a single call, during the Worked all Europe
Contest. Recently, during evening, at the greyline, using 800 watts (and no special receive antenna), I was able to work Diego Garcia (VQ9) and Austrailia (VK6). Hong Kong, Japan
and South Korea were also heard (but not worked) long path. During the CQWW SSB Contest, working only evenings, I was able to work 75 countries. Not bad for a $7 US wire
vertical. Each gave good signal reports, with some even commenting on the strength of the signal.

by kb0fhp originally available at http://home.comcast.net/~kb0fhp/80M_Vertical/80M_Vertical.htm

The Handi-Tenna 70 cm Portable Antenna

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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 it–it 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 Ohms–making 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 cap–gives 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.      Length      Spacing
Ref     13.00 (33 cm)     0.00
DE     See Sketch     4.50 (11.5 cm)
D1     12.00 (30.5 cm)     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

A multi-band super mini loop antenna

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Here’s 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 / can’t load
28.331 Mhz / SWR 3 to 1
29.650 Mhz / can’t load

Usually I can’t load on 10 meters.
40 and 20 are really quite good. Even 15 isn’t too bad.
Don, K8THU

End of excerpts from emails.

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

2 meter Cubical Quad Antenna

Posted in VHF Antennas 1 Comment

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. 

Cheap Yagi Antennas for VHF/UHF

Posted in VHF Antennas 1 Comment


Editors notes: 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 isn’t 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 you’re planning to build an EME array, don’t 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 dB’s/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 MHzREFDED1D2D3D4
3 EleLength
Spac’g		41.00
0.00
8.50		37.00
20.00
4 EleLength
Spac’g		42.00
0.00
8.50		37.50
19.25		33.00
40.50
6 EleLength
Spac’g		40.50
0.00
7.50		37.50
16.50		36.50
34.00		36.50
52.00		32.75
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 MHzREFDED1D2D3D4
3 EleLength
Spac’g		26.00
0.00
5.50		23.75
13.50
4 EleLength
Spac’g		26.25
0.00
5.00		24.10
11.75		22.00
23.50
6 EleLength
Spac’g		26.25
0.00
5.00		24.10
10.75		23.50
22.00		23.50
33.75		21.00
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.

432MHzREFDED1D2D3D4D5D6D7D8D9
6 EleLength
Spac’g		13.50
0.00
2.50		12.50
5.50		12.00
11.25		12.00
17.50		11.00
24.00
8 EleLength
Spac’g		13.50
0.00
2.50		12.50
5.50		12.00
11.25		12.00
17.50		12.00
24.00		12.00
30.75		11.25
38.00
11 EleLength
Spac’g		13.50
0.00
2.50		12.50
5.50		12.00
11.25		12.00
17.50		12.00
24.00		12.00
30.75		12.00
38.00		11.75
45.50		11.75
53.00		11.00
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 haven’t built any other versions. Driven element dimensions are L = 5.7″ and H = 1/2″ Elements are 1/8″ diameter.

902/3 MHzREFDED1D2D3D4D5D6D7D8
10 EleLength
Spac’g		6.20
0.00
2.40		5.60
3.90		5.50
5.80		5.50
9.00		5.40
12.40		5.30
17.40		5.20
22.40		5.10
27.60		5.10
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 MHzREFDED1D2D3D4D5D6D7D8
10 EleLength
Spac’g		4.30
0.00
1.70		3.90
2.80		3.80
4.00		3.75
6.40		3.75
8.70		3.65
12.20		3.60
15.60		3.60
19.30		3.50
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 ATVREFDED1D2D3D4D5D6D7D8D9
6 EleLength14.0012.5012.2512.2511.00
8 EleLength14.0012.5012.2512.2512.0012.0011.25
11 EleLength
Spac’g		14.00
0.00
3.00		12.50
6.50		12.25
12.25		12.25
17.75		12.00
24.50		12.00
30.50		12.00
36.00		11.75
43.00		11.75
50.25		11.50
57.25



450 MHz FM. Yea, I understand it’s 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 FMREFDED1D2D3D4
6 EleLength
Spac’g		13.00
0.00
2.50		12.10
5.50		11.75
11.00		11.75
18.00		10.75
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 AMSATREFDED1D2D3D4D5D6D7D8D9
6 EleLength13.4012.4012.0012.0011.00
8 EleLength13.4012.4012.0012.0012.0012.0011.10
10 EleLength13.4012.4012.0012.0012.0012.0011.7511.7511.10
11 EleLength
Spac’g		13.40
0.00
2.50		12.40
5.50		12.00
11.25		12.00
17.50		12.00
24.00		12.00
30.50		11.75
37.75		11.75
45.00		11.75
52.00		11.10
59.50

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

A 160 meter antenna for small lot

Posted in HF Antennas Leave a comment

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, didn’t’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

A short dipole for 80 meters

Posted in HF Antennas 1 Comment

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.