---
title: "Types of wired antenna"
subject: "Propagation and Antenna"
chapter: 3
key: "semester_6/propagation_and_antenna:wired-antenna-types"
source: https://www.bctengineer.com/q/semester_6/propagation_and_antenna/wired-antenna-types
site: BCT Engineering
---

# Types of wired antenna

Propagation and Antenna · Chapter 3: Antenna Classification

- Asked in: 2073 Magh, 2+4 marks
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/propagation_and_antenna/wired-antenna-types
- Whole chapter: https://www.bctengineer.com/md/semester_6/propagation_and_antenna/chapter-3

## Question

Define an antenna. List the various types of wired antenna with their radiation pattern and polarization.

## Short answer

Antenna converts guided EM energy to free-space waves. Wire antenna types include dipole (figure-8 pattern, linear polarization), monopole (omnidirectional, vertical), small loop (figure-8 in plane, linear), long wire (multi-lobe, linear), V/rhombic (directive, horizontal), and helical (end-fire, circular).

## Answer

#### Antenna

An **antenna** is a metallic structure (transducer) that converts guided electromagnetic energy from a transmission line into free-space electromagnetic waves, and vice versa during reception (IEEE: "a means for radiating or receiving radio waves"). It also matches the line impedance to free-space impedance (377 Ω).

#### Types of wire antennas

Patterns below are in the plane containing the antenna (E-plane), with the wire drawn vertical unless noted.

| Antenna | Radiation pattern | Polarization |
|---|---|---|
| Short (Hertzian) dipole | Figure-8, max ⊥ wire; omni in H-plane | Linear, along wire |
| Half-wave dipole | Figure-8, slightly narrower (HPBW 78°) | Linear, along wire |
| Folded dipole | Same as λ/2 dipole | Linear |
| Quarter-wave monopole | Upper half of figure-8, omni horizontally | Vertical |
| Small loop | Figure-8 in loop plane; null ⊥ to loop | Linear, in plane of loop |
| Long wire (resonant) | Many lobes; main lobes tilted towards wire | Linear |
| V and rhombic | Directive along bisector/diagonal | Horizontal |
| Helical (axial mode) | End fire along axis | Circular |
| Yagi-Uda, LPDA (wire arrays) | Unidirectional end fire | Linear |

```text
 Dipole / monopole       Small loop          Helix (axial)
      |  .-.                 .-.  .-.            ___
  .-. | (   )             (   )O(   )         |///| ===>
 (   )|  '-'               '-'  '-'            ‾‾‾
  '-' |                 max in loop plane    beam on axis
 max ⊥ wire, null on axis  null ⊥ loop       circular pol.

 Long wire (l = several λ)     V / rhombic
   \ / \ /                      <V   ===>
  ---------- wire               unidirectional
   / \ / \   lobes tilt           (terminated)
            towards far end
```

- **Dipole** antennas suit HF–UHF use (broadcast reception, TV, FM).
- **Monopole** is used for MF broadcast and mobile whips.
- **Loop** antennas are used for direction finding and AM receivers.
- **Long-wire, V and rhombic** are HF travelling-wave antennas.
- **Helix** gives circular polarization for satellite links.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What does an antenna do?
   A. Converts guided EM energy to free-space waves and vice versa, matching to 377 Ω
   B. Amplifies signals
   C. Generates RF
   D. Stores charge
   Answer: A. A transducer between line and space. (Key point: Definition)

2. What is the small loop pattern?
   A. Max along axis
   B. Figure-8 with max in loop plane and null perpendicular
   C. Omnidirectional
   D. Null in loop plane
   Answer: B. Maximum in plane of loop. (Key point: Small loop)

3. Axial-mode helix polarization?
   A. Horizontal
   B. Vertical
   C. Circular
   D. Elliptical only
   Answer: C. Used for satellite links. (Key point: Helix polarization)

4. Quarter-wave monopole pattern?
   A. Horizontal
   B. Full figure-8
   C. Unidirectional
   D. Upper half of figure-8, omni horizontally, vertical polarization
   Answer: D. Half-space dipole pattern. (Key point: Monopole)

## Related in Propagation and Antenna

- [Antenna radiation pattern and lobes](https://www.bctengineer.com/question.md?key=semester_6%2Fpropagation_and_antenna%3Aradiation-pattern) — Propagation and Antenna, chapter 2, asked 4×
- [Radiation pattern, gain and power flux density](https://www.bctengineer.com/question.md?key=semester_6%2Fpropagation_and_antenna%3Apattern-gain-power-flux-density) — Propagation and Antenna, chapter 2
- [Single wire radiation and omnidirectional antenna characteristics](https://www.bctengineer.com/question.md?key=semester_6%2Fpropagation_and_antenna%3Asingle-wire-radiation-omnidirectional) — Propagation and Antenna, chapter 1
- [Antenna polarization](https://www.bctengineer.com/question.md?key=semester_6%2Fpropagation_and_antenna%3Apolarization) — Propagation and Antenna, chapter 2, asked 8×
- [Antenna definition and single wire radiation conditions](https://www.bctengineer.com/question.md?key=semester_6%2Fpropagation_and_antenna%3Asingle-wire-radiation-conditions) — Propagation and Antenna, chapter 1, asked 4×
- [Pattern lobes and 180° out-of-phase array](https://www.bctengineer.com/question.md?key=semester_6%2Fpropagation_and_antenna%3Alobes-importance-opposite-phase-array) — Propagation and Antenna, chapter 2