Tapered Quarter Wave Tube. First described by Paul Voigt in 1930, TQWTs allow a good quality-to-price ratio. They are also easy to build. Similar to transmission lines, the TQWT is different by its shape, a kind of horn is used as back load but the driver is not placed at the beginning of the cone as usual but on its side. Quarter Wave Impedance Transformer Calculator. The quarterwave impedance transformation calculator is used to match an input and an output impedance at a given frequency for maximum power transfer. Input impedance (Ohms) Desired output impedance (Ohms) Note: This transformer cable should be electrically one quarter wavelength, or a multiple of. Tapered Quarter-Wave Tube First described by Paul Voigt in 1930, TQWT/QWT uses like a transmission line design pipe lenght of 1/4 wavelenght of driver's resonance frequency. TQWT and QWT stands for (tappered) quarter wave tube and are also refered as Voight Pipes. Tapered Quarter Wave Tube (TQWT) loudspeakers. The TQWT is among the best loudspeaker enclosures I know. It will let you hear music as music is meant to be heared: all the details are being passed to you at the speed of light and it will give you a up-front projection of the stage.Not every unit is good for this enclosure: units designed for the use in a horn won't do good at all.

Ground plane antenna calculator

Bass Reflex Box Calculator Onken Bass Reflex Calculator Calculate Speed of Sound in fibrous material Calculate the Required Amplifier Output Power Calculate Back Loaded Exponential Horn Calculate Tapered Quarter - Wave Tube Calculate Baffle Diffraction Loss.

Ahh, the good old quarter wave ground plane! This calculator can be used to design a Quarter Wave Ground Plane antenna, with radials. The radiating element is a quarter wave (λ/4) and the radials are 12% longer. There are usually four radials, three being a minimum, but you could use up to six. This is a true unbalanced antenna, with a feed impedance of around 50Ω and therefore a great match to 50Ω unbalanced feedline. The velocity factor is set to 95% which should be fine for most people. You could cut a little on the large side and trim the antenna for best match at your desired frequency if you have the equipment.

These antennas can easily be built for UHF or above by using a chassis mount N-Type (or SO-239) connector, some solid wire and solder. For VHF and below, as the elements get bigger, some more structured design is needed.

A quarter wave monopole mounted against a perfect ground will have an impedance of around 36Ω but by bending the radials down at an angle of 45°, we increase this to around 50Ω whilst at the same time lowering the radiation angle more towards the horizon. (42° is the theoretical perfect angle for 50Ω feed, but who’s measuring!)

I have made quite a few of these antennas over the years with good results. They are very forgiving due to the low impedance feed. I use one at home on 70MHz, click here to see construction details and more images.

The next two images show one I built for the 70cm band. It is good for use between 430-440MHz. It uses 6mm aluminium tube for the radials, 4mm brass tube for the driven element and is built around an N-Type chassis socket mounted to a 40x40mm aluminium square, held together with rivets.

Below is some images of one I built using an SO-239 socket riveted to a piece of aluminium sheet, with telescopic elements. This means it can be used on any frequency between 80MHz and 410MHz (It’s a shame they don’t go a bit smaller and a bit larger, so it could cover 4m and 70cm, but they are what they are). It’s a good antenna for testing.

Here it is set up in the garden for testing on 145.500MHz

And, the impedance and reactance are perfect!

Ground Plane Antenna Calculator

Below is a quarter wave ground plane antenna I made for 23cm, 1296MHz which is made from off-cuts of household mains copper wire and a scrap BNC socket from the junk box.

The one pictured below is for receiving ADS-B aircraft signals on 1090MHz, again using scrap copper, but this time a purchased N-Type chassis socket.

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Featured Antenna from Kai Siwiak, KE4PT

Off Center End Fed Dipole 6m - 40m Intended use for apartment dwellers and mobile deployment

Featured Presentation from Pete Rimmel, N8PR

Ground plane antenna calculator

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Antenna Length Chart for Quarter, Half & Full Wave

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Attic Coaxial-Cable Trap Dipole for 10, 15, 20, 30, 40, and 80 M

Twin Lead 40M Dipole

This Old Dipole 40M Dipole

New Carolina Windom

WC7I The truth about SWR***This is a very good site with clear explanations

The Truth About the G5RV Antenna

Antenna Theory The page is not strictly related to amateur radio antennas but the theory is universal

W8JI A plethora of great antenna types plans & builds plus many other useful topics with explanations & clarification

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Coat Hanger / Copper Wire 2 Meter Yagi Antenna

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Zepp Antenna Theory

Windom Antenna Theory

40/80 Meter Inverted V Dipole Antenna

Antennas for Difficult Situations

G7FEK Limited Space Antenna Nested Marconi Antenna

Doublet aerial for HF amateur ham radio short wave bandsSome general talk about design and builds, worth watching, useful info

Antenna Manufacturers - Masts - Towers - Rotors

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Additional Antenna Links

  • Hex-Beam Construction page by K4KIO - EXCELLENT hex-beam site by Leo Shoemaker , K4KIO.
  • Cubex Company -- HF Quads as well VHF lines
  • Quarter Wave Box Calculator Game

  • OptiBeam -- Antennas from Germany!
  • Chameleon Antenna -- An innovative antenna design for fixed / portable or mobile use, and covering 6-80 meter bands! VERY nicely made, too!
  • Antenna Magic Page -- Ray Jurgens, KQ6RH. MANY lightweight and portable designs!
  • MFJ / Hy-Gain
  • Comtek Systems -- Makers of Four Square phased array antenna systems
  • M2 Antennas --Wide line of single and multi-band yagis.
  • Ray Jurgens -- Antenna Magic
  • Wolf Radio -- Antennas for CB, ham, and FM broadcast
  • Array Solutions -- Wide line of antennas, phasing, switching, matching, and contesting needs . . . . amateur radio, commercial, and military!
  • Penninger Radio -- Manufacturers of an EXCELLENT line of antenna materials, tube joiners, guy rings, hitch mounts & MUCH more!
  • Antennas.us-- WIDE range of antennas from military , amateur, and mobile to GPS, WLAN/Wi-Fi/WiMax and TV!
  • Rick Adams -- Makers of cubical quad spiders for CB and ham radio use
  • Myers Engineering -- Providers of original and custom antenna design, antenna engineering, and antenna development and manufacturing services
  • Radio Works RF Consulting -- Broadcast & communications design & repairs, coaxial & waveguide systems testing, grounding systems design
  • 2.4ghz antenna wire lengthAntenna length calculator
  • Hex antennas and hex antenna parts by K5BOB, including unique non-metallic base plates of UHMW material
  • The Antenna Ranch -- Radial plates, baluns, antennas
  • Quarter Wave Box Calculator
  • Qtenna boomless quad hubs and quad hardware -- Boomless quad hubs and quad hardware by Steve Narducci, W9SN
  • NI4L Antennas & Electronics -- Antennas custom made to your frequency of choice!
  • RadioWavz -- Manufacturers of many wire antennas, including Hex antennas that cover 40 meters! (And now the world's first 160 – 10 meter Hex
  • antenna!
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