Yesterday, while walking in the area of the Voronya and Orekhovaya mountains, I met a radio amateur I knew who was renting a summer cottage there with his family. I promised to tell him about the W3EDP HF antenna.

Introduction

A radio amateur from the village of Dudergof (near Orekhovaya Gora) showed the short-wave equipment that he transports in the trunk of a car:

• Chinese transceiver with built-in antenna tuner (in a suitcase from a hardware store),
• iambic telegraph key,
• base in the form of a bracket for the roof rail (rails are external parts of the car body in the form of two slats on the sides along the roof, intended for installing a trunk),
• a 2 meter high pin with an open extension spool, which can be transported in the trunk and screwed to the bracket on the roof rail.
  Such a kit, according to the radio amateur, “is built with a tuner for all HF bands, which makes it easy to go on the air from a car.” All that remains is to take the highway higher up the mountain (in this locality it is the village of Kavelakhta), where closer to the top of the mountain there is a functioning church on the site of the destroyed church of Princess Olga (address: Krasnoe Selo, Dudergof territory, Twenty-Fifth October Avenue, 97).

Also, in the garden plot, a radio amateur raises the Inverted Vee antenna, apparently for operation on 80 and 40 meters.
It seems to me that the set of equipment is quite optimal - the only thing that confuses me is the pin with the extension coil, which is not widely available and is difficult to replicate.

Therefore, I previously chose W3EDP - a wire antenna, which is easier to make yourself and install next to a car or in the country. For example, it does not require connecting the cable braid to the vehicle ground, which can only be obtained by partially disassembling the fastening of the roof rails to the body.

Design of the classic W3EDP antenna

АнтThe enna W3EDP is a variation of the End Fed for short wave, but with an input impedance of 200 ohms. It uses a 4:1 transformer. The antenna was first proposed by H. J. Siegel in 1936.

The W3EDP antenna consists of:

• emitter 83 feet long (25.6 meters)
• counterweight 17 feet long (5.2 meter), which performs the function of “ground” and does not participate in radiation.
  The emitter is made in the form of an L-shaped sheet, on a mast of 5 meters, so the horizontal part is almost 1 wavelength of the 14 MHz range - 20.6 meters, and the total length of the sheet is 1.5 wavelengths.
  

The use of a wave emitter causes a horizontal conductor to emit not into the “clouds,” but at angles near the horizon, even the lowest located conductor. The vertical part is responsible for circular vertical radiation like GP. The total radiation from the vertical and horizontal parts of the antenna is suitable for short and medium distances - not for DX. But, a small amount of energy from QRP transmitters is concentrated within the radius of the first radio wave jump.

In the original W3EDP, the matching of 200 ohms to 50 ohms coaxial cable is done using an inductively coupled circuit, as in a Fuchs antenna. However, in modern conditions it is more profitable to use a manual tuner or UnUn, since there will be no voltage in the 14 MHz range at the body of the T-tuner or the “cold” end of the UnUn, because a resonant 1/4-wave counterweight 5.2 meters long is connected to it. To match a high input impedance with a low one, you can use UnUn 4:1 or BalUn 4:1 instead of a T-tuner, provided that the length of the antenna blade is trimmed to achieve a minimum SWR.

Also, you can use the antenna in the 7 MHz range, but the counterweight will have to be extended to 10.5 meters. Instead of extending the counterweight, the classic W3EDP antenna switches to a different counterweight length.
The input impedance of such an antenna with a blade length of 0.6 wavelength, as you might guess, will also be high - about 100-150 Ohms, with a reactive component.

In the 3.5 MHz range, in my experience of permanently installing this antenna at a summer cottage, if you use a short counterweight, then RF voltage will be present on the radio station body during transmission, the microphone and body, and the telegraph key will burn. Therefore, in the 80 meter range it is better to also use a 1/4 wave counterweight with a length of 20 meters. The resistance of such an antenna in the 80-meter range is low, about 60 Ohms. All local stations respond to CQ the first time, at 100 W - ratings 5.8-5.9, but distant stations, or even from neighboring Belarus, will complain about a weak signal (since the installation height of the antenna for the 80-meter range is clearly insufficient).

Differences between W3EDP and the 14 MHz Ground Plane antenna
1) Ability to receive and transmit in other bands: 3.5 and 7 MHz. Where the shortened GP is dull or ineffective.
2) Directivity in the 14 MHz range - in one direction, against the antenna fabric. Whereas GP is 360° omnidirectional.
3) Input impedance 200 Ohms versus 36-50 Ohms. The radiation resistance is much higher (75 Ohms versus 10-30 Ohms), because the center of radiation is higher above the ground. An antenna with a high input impedance is not demanding on the number of counterweights, and there is less loss in the ground and near zone. With one counterweight, the gain is W3EDP about 1-2 dB (GP has a gain of 0 dB with a large number of counterweights).
4) Due to its large length, the W3EDP can be used as a receiver in the medium wave bands for the MW DX hobby.
5) The radiation angle in the vertical plane of the GP is flatter, which means the GP is better suited for long-distance, DX radio communications. W3EDP is more suitable for short and medium distance QSOs.

Differences between W3EDP and End Fed antenna
1) The length of the canvas is longer - instead of 20 meters (for UnUn 64:1), here the length of the canvas is 25.6 meters (for UnUn 4:1), of which 5 meters go up.
2) Specific directionality in the 14 MHz range. EndFed has a symmetrical, bidirectional polar pattern.
3) Input impedance 200 Ohms versus 1500-3000 Ohms.
4) Due to the lack of a strict connection to the half-wave resonance, the antenna of the above dimensions works not only on even harmonics 2 and 4 (where SWR = 1...2), but also on odd ones - 3 and 5.

Differences between W3EDP and InvV antenna
1) The food is not in the center, but from the edge, like the End Fed.
2) In the 14 MHz range, it is not demanding on installation height.
3) W3EDP - multi-band HF antenna, subject to switching counterweights.
4) Adjustable using a tuner in the ranges of 160-10 meters. The W3EDP antenna is convenient if you have a manual or automatic tuner.

W3EDP antenna modifications

1) Instead of a counterweight lying on the ground, you can use a vertical two-wire 450 Ohm line - then the 1/4 wave line acts as a resistance transformer from high input impedance to low. The resulting antenna is known as the Zeppelin. This type of antenna was used in the era of aeronautics (a two-wire line and its continuation - the antenna wire was unfurled from the airship).

More details:
https://qrznow.com/w3edp-antenna/

2) Tilt of the emitter towards the ground leads to switching of the radiation pattern. Gain at low angles is obtained in the direction of inclination.

3) If you plan to work only in the range of 40 meters, increasing the length of the web from 25.6 meters to 30 meters has a positive effect on the antenna parameters: there is no reactance, and the input impedance of 112 Ohms can be matched using a 1/4-wave length of 75 Ohm cable (partially coiled into a shut-off choke). The bandwidth is 7.06...7.3 MHz = 240 kHz.

4) W3EDP doubled - 61 meters long, counterweight 40 meters. Input impedance 50 Ohm, gain -0.3 dB.
For operation only in the range of 160 meters.

Classic W3EDP antenna in multi-band mode

The W3EDP antenna, like the Zeppelin, operates on harmonics. But, unlike the Zeppelin, you need to switch the counterweights - each range has its own length.

When using a 4:1: transformer

*with counterbalance 5.2 meters in the range of 20 m (14.1 MHz), power supply to the lower corner of the antenna, input impedance 200 Ohms.
SWR(14MHz)=1.5, the bandwidth for SWR<2 level is 13.5...14.4 MHz.

*with counterweight 10.5m on 40m range (7.1 MHz), with the same configuration:
SWR(7.1MHz)=3, band 7.4...8 MHz.

*with counterweight 7.5m in the range of 15m (21 MHz), with the same configuration:
SWR(21MHz)=2, band 21...21.3 MHz.

*with counterweight 2.4m in 10m range (28 MHz), with the same configuration:
SWR(28.2MHz)=5.

When the feed point is shifted upward, to a height of 1.5 meters, the SWR deteriorates to 4, which is associated with radiation from the counterweight (it is advisable to place it horizontally, along the surface of the earth).

In the 3.6 MHz range, the classic W3EDP with a 4:1 transformer does not work, since you need to use a 1:1 transformer (antenna input impedance is close to 50 Ohms).

Comparison of W3EDP with LW ("long wire") antenna when operating in multi-band mode

For comparison, I will give a version of the Long Wire (LW) antenna calculated in NEC-2 for MMANA, designed for operation in several bands.

Transformer 9:1
Horizontal canvas 34 meters.
Counterweight 5.2 meters.
Installation height 1.5 meters. Feed to the upper corner (where the horizontal fabric should be stretched “into a string”).

Antenna LW 34+5.2m:

When the horizontal part - the emitter is lengthened to 35 meters, and the counterweight is shortened to 4.2 meters, the SWR in the 7 MHz range improves, otherwise unchanged:

Antenna LW 35+4.2m:

As you can see, with an input impedance of 450 Ohms (9:1 transformer), the “long wire” antenna operates in more number of ranges, but W3EDP (transformation ratio 4:1) has better matching in one range, provided the counterweights are switched.

Also, the W3EDP with 1/4 wave counterweight will not have a "hot" touch to the radio during transmission, because tension is removed from the body. Grounding from the radio station is not necessary to avoid current loops (star grounding is necessary). Near the power point, i.e., where the matching device (UnUn or tuner) is located and the counterweight is connected, lightning protection can be implemented in the form of a pin driven into the ground (radio grounding is connected to electrical grounding).

Comparison of W3EDP with EndFed antenna (with 64:1 impedance transformer)

The EndFed antenna has one short counterweight (cable braid is often used) - 2 meters long and a canvas 19.7...20 meters long. The input impedance of EndFed is high and amounts to 2-2.5 kOhm, and therefore a 64:1 impedance transformer is used.
Using a 20 meter cable, EndFed operates in the 7 and 14 MHz bands without switching. Whereas the W3EDP antenna requires switching counterweights: 5.2 or 10.5 meters.

Conclusion: W3EDP is almost equal to EndFed in terms of quality of matching with the cable. In this case, instead of the scarce UnUn 64:1, you can use either the popular BalUn voltage 4:1, or a matching device (tuner), manual or automatic, because 200 Ohm is a more convenient resistance for matching. than 2000 Ohm.

Links:
W3EDPAntenna - AE5VV
W3EDPpresentation.pdf presentation

Date of last change: 07/21/2025 - phraseological errors have been corrected.

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