What Is a V Antenna?
A V antenna is a directional wire antenna formed by two conductive elements extending outward from a common feed point. When viewed from above, the two antenna legs form a clear V-shaped structure.
The V antenna can be regarded as an improved arrangement of two long-wire radiators. By selecting an appropriate leg length and included angle, the radiation produced by the two wires can reinforce in selected directions, providing greater directivity than a single straight long-wire antenna.
V antennas are commonly associated with high-frequency communication systems, particularly in the HF range. However, their operating frequency is not determined by a fixed band alone. The actual performance depends on the electrical length of each leg, the apex angle, feeding method, installation height, surrounding ground conditions, and whether the wire ends are open or terminated.
Structure and Operating Principle
A typical V antenna consists of two long-wire elements connected to a balanced feed point at the apex of the V. The currents in the two legs are excited differentially, meaning they have equal magnitudes and opposite instantaneous directions at the feed point.
Each wire produces its own radiation pattern. When the antenna geometry is selected correctly, the major radiation lobes generated by the two legs overlap and combine along the central axis of the V. This field addition increases the radiation intensity in the desired direction and improves antenna directivity.
Two angles are often used when describing the structure:
- The angle between the two antenna legs is the included or apex angle.
- The angle between one leg and the central axis is half of the included angle.
The optimum angle is not a universal fixed value. It changes with the electrical length of the antenna legs and the intended operating frequency.
V antenna structure with two long-wire elements and apex angle
Resonant and Terminated V Antennas
V antennas can generally be divided into two configurations.
An open-ended or resonant V antenna reflects part of the current wave from the ends of its conductors. These reflections create standing waves along the antenna legs. This type of antenna normally produces a bidirectional radiation pattern, with strong radiation in two opposite directions along the antenna axis.
A terminated V antenna uses resistive loads at the far ends of the two wires. The loads reduce current reflections and help maintain traveling-wave operation. This can suppress radiation in the reverse direction and create a more directional end-fire pattern.
The terminated design usually provides more consistent directional behavior across a wider frequency range, but some RF power is dissipated in the terminating resistors. The antenna designer must therefore balance bandwidth, directivity, efficiency, and power-handling requirements.
Frequency Range and Electrical Length
Traditional V antennas are widely used in the HF range from approximately 3 to 30 MHz because the long wavelengths in this band make wire-based antenna structures practical for fixed communication installations.
However, the V antenna is defined by its geometry and electrical length rather than by one mandatory frequency range. Each leg may be one-half wavelength, one wavelength, or several wavelengths long, depending on the required radiation pattern and gain.
As the electrical length of the legs increases, antenna directivity can generally improve. At the same time, additional side lobes may appear, and the radiation pattern can become more sensitive to frequency, installation height, ground conductivity, and construction tolerances.
Radiation Pattern and Directivity
The radiation pattern of a resonant V antenna is commonly bidirectional. The fields generated by the two wire elements combine to form major lobes approximately aligned with the central axis of the V.
The final radiation pattern is determined by several factors:
- Length of each antenna leg
- Included angle between the legs
- Operating frequency
- Feed-point impedance and matching
- Installation height above ground
- Wire diameter and conductor loss
- Open-ended or terminated configuration
Increasing the leg length can produce higher directivity, but it can also create stronger side lobes. For this reason, antenna gain should not be considered independently from beamwidth, side-lobe level, front-to-back ratio, and impedance performance.
Bidirectional radiation pattern of a resonant V antenna
Feeding and Impedance Matching
Because the V antenna is normally a balanced wire structure, it is commonly fed with a balanced transmission line. If coaxial cable is used, a suitable balun or matching network may be required to reduce common-mode current on the cable and maintain a symmetrical radiation pattern.
The input impedance changes with leg length, apex angle, operating frequency, installation height, and nearby structures. Proper impedance matching is important for reducing reflected power and achieving stable system performance.
In practical antenna development, engineers normally evaluate return loss, VSWR, radiation pattern, gain, polarization, and efficiency before finalizing the antenna geometry.
Advantages of V Antennas
The V antenna offers several practical advantages:
- Simple wire-based construction
- Higher directivity than a single long-wire element
- Relatively low manufacturing cost
- Suitable for large fixed HF installations
- Flexible leg length and apex-angle design
- Available in resonant and traveling-wave configurations
Design Limitations
V antennas also have several limitations:
- They require considerable installation space at lower frequencies.
- Resonant versions may produce strong standing waves.
- Long antenna legs can generate significant side lobes.
- Performance can change noticeably with frequency.
- Ground conditions and installation height can affect the radiation pattern.
- Terminated versions sacrifice some efficiency because power is absorbed by the loads.
Typical Applications
V antennas have traditionally been used in:
- HF point-to-point radio communication
- Shortwave transmitting and receiving stations
- Long-distance fixed communication links
- Radio monitoring and signal-reception systems
- Communication research and antenna education
- Directional wire-antenna experiments
- Emergency and remote-area communication systems
Engineering Significance
Although modern communication systems increasingly use compact arrays, horn antennas, broadband antennas, and electronically controlled antenna systems, the V antenna remains an important model in antenna theory.
It clearly demonstrates how conductor length, current phase, antenna geometry, and field superposition influence gain and radiation direction. Understanding these relationships is valuable when studying more advanced antenna structures, including phased arrays, broadband measurement antennas, directional microwave antennas, and antenna test systems.
RF MISO develops antenna and microwave solutions for RF testing, measurement, communication, radar, and system integration applications. A solid understanding of fundamental antenna structures helps engineers select suitable products and evaluate key parameters such as gain, polarization, beamwidth, impedance, and radiation pattern.
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Post time: Jul-10-2026
