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This web article details the construction of a 4-meter band coaxial dipole antenna, designed for operation between **70.000 MHz and 70.500 MHz**. The resource provides a bill of materials and step-by-step assembly instructions for a half-wave dipole constructed from _RG-58_ coaxial cable. The design specifies a direct 50 ohm feedpoint impedance, eliminating the need for an external matching network. Construction photographs illustrate the stripping and soldering processes for the coaxial cable elements, ensuring proper electrical connection and physical integrity. The article includes specific dimensions for the radiating elements, derived from calculations for the 70 MHz band. The project outlines the physical dimensions required for resonance at 70 MHz, with the outer braid forming one half and the inner conductor forming the other. The feedline connection is directly to the coaxial dipole's center, maintaining a 50 ohm characteristic impedance. While the article does not present SWR plots or VNA sweeps, it focuses on the mechanical construction and dimensional accuracy for achieving a functional 4-meter dipole. The design is intended for fixed station use, with no specific mention of polarization or height above ground, but implies a standard horizontal orientation for dipole operation. DXZone Focus: Web Article | 4m Coaxial Dipole | Construction Guide | 50 ohm Feed

This design has the following advantages low-cost components, Easy to set-up - nothing to adjust, no metalwork required, and only four soldered joints!

The antenna in this project is a modification of the techniques used to design a multiband fan type dipole with little or no tuning involved having a total space of 105 feet

The OZ1CX center-loaded mobile antenna project details the construction of a compact **80-meter** antenna, specifically designed for mobile, portable, and stationary operations. It features a loading coil wound on a 50 mm PVC pipe with 1.5 mm copper wire, comprising 100 turns over 150 mm length, resulting in an inductance of 150 µH. The design incorporates a 1.5-meter whip and a 1.5-meter base section, with the coil positioned at the center for optimal performance on the 3.5 MHz band. Performance measurements indicate a **VSWR** of 1:1.2 at 3.7 MHz when mounted on a vehicle, achieving a bandwidth of 30 kHz for VSWR below 1:2. The antenna's efficiency is compared to a full-size dipole, showing a signal strength reduction of 3-4 S-units, which is typical for compact mobile HF antennas. Practical application notes cover tuning adjustments by varying the whip length and coil tap points, emphasizing the importance of a good ground plane for effective operation.

An article describing a homemade 40m wire OCF Dipole

Documents the construction of a **VHF/UHF** antenna addition for the Buddipole HF antenna system, leveraging the existing Versa-Tee component. The project details the fabrication of a custom antenna mount from angle aluminum, including specific drilling and tapping for 3/16"-24 bolts, and the creation of radials from Simpson Strong Tie Insulation Supports. It specifies radial lengths for 70 centimeters (6 inches from the center stud) and 2 meters (19 1/4 inches), noting the use of wire nuts for safety. The resource outlines the construction of a mast from 1/2" ID PVC conduit, connected with 3/8"-24 connecting nuts and bolts, mirroring the Buddipole's modular design. It describes the integration of a mobile dual-band antenna with a 3/8"-24 mounting stud and the custom coax setup with BNC and **PL-259** connectors. Field testing with an FT-817ND and a separate dual-band SWR meter confirmed good SWR on both 2 meters and the 440-450 MHz section of 70 centimeters, with positive reception reports during Field Day activities. Further, the article describes the creation of a custom carrying solution, including a 22-inch tripod bag and a fabric roll-up, to emulate the portability of the original Buddipole system.

This LPDA calculator is based on the design procedure as described by L. B. Cebik, W4RNL (SK) in the 21st edition of The ARRL Antenna Handbook.

The radiating part is the vertical half of the dipole. You get nearly radiation in all directions, the second half must not be in 180°. The table below show how we get an impedance for direct feeding of 50Ohm coax. by DK7ZB

A dual band dipole antenna for 40 and 80 meters band. Total lenght of 26 meters, foreseen two coils at aprox 11 meters distance from center feed.

Antenna directivity and gain are fundamental concepts for any radio operator, as this article from _Electronics Notes_ explains. Real-world antenna designs, unlike theoretical isotropic radiators, do not radiate equally in all directions; their radiation patterns are often visualized using **polar diagrams**. These diagrams illustrate how power is focused in desired directions, crucial for both transmitting and receiving applications. The article clarifies how antenna performance is identical for both transmission and reception, a key principle for understanding antenna specifications. Operators often encounter terms like _beamwidth_, which defines the angle where power falls to half its maximum level, or -3dB. Understanding this parameter is vital for accurately orienting directional antennas like a Yagi. The discussion also differentiates between antenna gain expressed in dBd (decibels over a dipole) and dBi (decibels over an isotropic source), noting that dBi figures will always be **2.1 dB** higher than dBd. This distinction is critical when comparing antenna specifications to ensure an accurate assessment of performance. Furthermore, the article touches on the front-to-back ratio, another important metric for directional antennas, and the balance between maximizing forward gain and achieving an optimal front-to-back ratio.

A very popular method of making a short dipoles resonate at a given frequency. This type of antenna is suitable for single band, narrow bandwidth use.

A simple dipole for 40m band feeded with 450-Ohm openwire feedline includes MMANA Gal files to download

Complete collection of the four main parts of this excellet research on modelling and designing half wave dipole antennas for 40 meters band, covering all aspects beginning from full wave length antennas, to shortened, loaded and reshaped dipoles

A simple portable antenna for SOTA VHF is described in this article dedicated to portable operations

This variation of the basic horizontal, half wavelength flat top dipole has proven to be a simple, effective antenna suitable for both home and portable use.

Multiband Trap Dipole, portable short antennas, accessories and kits by DG1DBM

A multiband Fan Dipole that works on 40 20 15 meters band, making a folded dipole for 7 MHz band and additional element for the 21 MHz and 14 MHz

Full article on how to build a home-made wire dipole antenna for 40 and 80 meters band. Article is fully in italian, as it was published on ARI RadioRivista, but is plenty of self explaining pictures that will guide you on homebrewing this trapped dipole antenna for the lower amateur radio bands.

Experimenting OCF and dipole wire antennas over house roof. Effects of roofs on wire antennas

One of the classic arguments in amateur radio is whether a dipole or vertical is the best antenna

In this article, author examine stresses placed on common-mode chokes (aka baluns) as hams use/abuse them, examine the efficiency of simple dipole multi- band antennas and their feed systems. Stressing a Balun.

Roach pole vertical antenna for 40 and 30 meters band featuring good performance on short skips contacts compared to wire dipole

Extending The Bandwidth of 80 Meter Dipoles

An inverted V Dipole antenna for HF bands, working on 10 20 40 and 80 meters band. PDF Presentation

A Six-element Yagi Beam for 6 Meter by W1JR proiddes a power gain of 10.2 dB over a dipole it is built on a 24 foot long boom

An antenna for 80 meters band for those who does not have enough space to setup a halwave wire dipole that is aprox 130ft or 40 meters. The antenna is an open-wire-fed shortened dipole

Homebrewing a Lightweight linked dipole HF antenna for portable SOTA operations

Experimenting a 20 40 meter short coil loaded dipole antenna with the goal to keep the total length under 40 feet so that the dipole can be mounted on two 20 foot fiberglass pole to make a 20/40 meter rotatable dipole.

Documents the OC1I and OC6I IOTA DXpeditions to Peru, specifically highlighting operations from SA-098 (Isla La Leona) and SA-076 (Isla Lobos de Afuera). The OC1I team logged over **8000 QSOs** from SA-076, while OC6I made 1400 QSOs from SA-098, despite challenging propagation conditions. The resource details the equipment used, including an _IC-7000_, an IC-706mkIIG, and a TS-440SAT, along with various antennas such as a 160m dipole, FD4, G5RV, and a multi-band vertical for 17m, 20m, 30m, and 40m. The DXpedition dates are specified: OC6I operated from SA-098 between December 28 and December 30, while OC1I was active from SA-076 from January 2 to January 7. Both operations are confirmed as valid for IOTA credit. The page also includes a video link for the OC6I operation and a photo gallery from the DXpedition. Feedback is welcomed, and the webmaster is identified as Bodo Fritsche, DL3OCH.

A **dipole antenna's** performance characteristics, specifically its gain and main angle of transmission, are significantly influenced by its height above ground. This resource presents a graphical interpretation of a study conducted by Mike Banz, AA3RL, which explored these critical relationships. The original study's tabular data has been converted into easily digestible graphs, allowing for a clearer understanding of how varying antenna heights affect the **radiation pattern** and overall efficiency. The analysis focuses on the practical implications for amateur radio operators, demonstrating how antenna placement can optimize signal propagation for different communication objectives. Understanding these principles is fundamental for effective station setup, whether aiming for local contacts or long-haul DX. The visual format aids in quickly grasping the complex interplay between physical setup and electromagnetic wave behavior.

The folded dipole antenna, often claimed to offer increased bandwidth and a close match to 300-ohm line, is examined in detail. This analysis challenges several prevalent myths, including the assertion that a folded dipole inherently provides wider bandwidth than a thin wire dipole on a single band. The article clarifies that any bandwidth improvement primarily results from the antenna's increased thickness, not from stub effects, folding, or higher feedline impedance. It also addresses the misconception that a folded dipole is an effective multiband antenna, explaining its poor performance on even harmonics where it presents a near dead short. Further discussion refutes the idea that SWR variations are less with changes in antenna length or frequency compared to a regular coax-fed dipole. The resource demonstrates that SWR variations are essentially similar, with folded dipole impedance ranging from approximately 200 to 300 ohms, leading to comparable SWR levels. It also corrects the belief that balanced line feed inherently offers low loss at high SWR, emphasizing that loss is primarily related to the physical characteristics of the transmission line rather than its balanced nature. Modeling results are presented, comparing a folded dipole with 300-ohm and 200-ohm feed lines against regular dipoles fed with 50-ohm and 75-ohm coaxial cable, and a single #14 insulated wire dipole. The data shows negligible differences in 2:1 VSWR bandwidth between folded and regular dipole systems when effective wire diameter is constant, reinforcing the argument that thickness is the dominant factor in bandwidth.

An experimental prototype of an asymmetrical hatted vertical dipole antenna that can work on HF bands 20 to 10 meters band. The AHVD Vertical dipole is an upside-down T design

A folded dipole is an antenna, with two conductors connected on both sides, and folded to form a cylindrical closed shape, to which feed is given at the center.

This DIY vertical multi-band Windom antenna offers a practical and effective solution for amateur radio enthusiasts seeking a versatile and compact antenna for HF communications. Its simplicity of construction, multi-band capability, and favorable performance make it a valuable addition to any radio shack. The article provides detailed instructions on constructing the antenna and balun, along with diagrams and component specifications. Field tests demonstrated successful contacts with stations across Europe and North America on 14, 18, and 28 MHz. The antenna exhibited comparable performance to a W3DZZ dipole and outperformed a Cobweb antenna on 18 MHz. Low noise levels were observed, effectively suppressing background noise.

A trap antenna dipole covering two differen bands made reusing an old 160/80m inverted vee antenna.

STAR-H Corporation specializes in extremely wideband dipoles and compact low-profile antenna systems for military, emergency management, commercial operations and consumer wireless applications.

Maxcon makes and sells Amateur Radio Antennas. Double extended Zepp antenna, multiband dipoles, bazooka antennas, and VHF Jpole, made in USA

The CobWebb antenna project is a compact, multiband HF solution ideal for amateur radio operators. Covering 14-28 MHz, it features a square dipole array with near-omnidirectional coverage and unity gain. This guide details a DIY approach, using a 1:4 current balun for impedance matching. Construction involves aluminum and fiberglass tubing, with optimized element tuning for SWR performance. Weather resistance improvements and resonance shift considerations are also discussed. Build your own CobWebb antenna for an efficient, space-saving HF experience.

QRSS operations on 30M with an home made dipole

This antenna is an off-center fed spiral dipole for 40 meters. The spiral dipole is very compact, making it well-suited for limited space (like an apartment patio), while the off-center feed gives the antenna some multiband capability.

The 2.6 Mhz M Dipole is constructed from #10 stranded insulated wire available in most hardware stores. The feedpoint uses a T-section of PVC pipe

RSGB article for beginners. How to build a dipole antenna, construction tips and correct setup of inverted-ve dipole antennas

Antenna may be made practically from any wire (strand, solid) having a reasonable diameter 0.5 2.0 mm (24- 12 AWG). Antenna may be installed at any balcony of 3 to 6 meter length.

Diamond W8010 Multiband Dipole Modifications

Sort of similar to the one of the 6m omni. Instead of using twin-lead, this design makes use of a more or less regular double bazooka antenna (coaxial dipole). Your attention shall be drawn to the available standart literature, such as Rothammel. In order to "compute" the dimension, Karl Rothammel mentioned that the total length of the dipole shall be 95% of the free-space wavelength. The short-circuit bridges (closing the folded dipole) are to be placed at a distance-fraction being equal to the velocity factor of the coax cable used, which will be 66% using RG-58 or RG174.

How to setup and configure the buddipole antenna in the J-Pole mode for the six meter band

The two dipoles are parallel with a distance of 12 cm and are also fed in parallel. The total length of the 4 m dipole is 208 cm and the 6 m dipole is 280 cm.

The OCFD Off-Center-Fed Dipole Antenna is an excellent multiband antenna that is relatively simple to construct, yet gets quite decent performance.

Measuring noise fiugre on the W2IMU horn and the dual-dipole-feed

The video delves into the fascinating science behind antennas, which are crucial for receiving and transmitting electromagnetic waves. It explains how antennas convert electric signals into electromagnetic waves for transmission, and how they operate through the oscillation of positive and negative charges in dipole arrangements. Practical antenna implementations, such as dipole antennas for TV reception and Yagi-Uda antennas with reflectors and directors, are also discussed alongside modern dish TV antennas with parabolic reflectors for signal processing. It's a comprehensive overview of how antennas work and their significance in communication technology.