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Cubic quad antennas are renowned for their high gain, excellent front-to-back ratios, and low angles of radiation, making them a popular choice among amateur radio operators. This resource provides detailed designs for constructing cubic quads optimized for 2, 6, 10, 12, and 15 meter bands. The lightweight structure can be easily built using fiberglass tubes and central hubs, allowing for portability and ease of assembly. The article discusses the specific dimensions and configurations required for both HF and VHF applications, emphasizing the importance of proper spreader lengths and boom dimensions. It also highlights the challenges of assembling larger cubic quads in limited spaces, offering practical solutions for hams with smaller backyards. With a focus on multi-band operation, this guide serves as a valuable resource for both novice and experienced operators looking to enhance their antenna systems.

This antenna is fed for vertical polarisation, to give a low angle of radiation for DX and also a nearly omni-directional radiation pattern.

Demonstrates the construction of **magnetic loop antennas**, detailing both multi-turn and single-turn designs. It covers a 30-inch diameter multi-turn loop for 80 meters, based on a February 1996 QST article, and an octagon single-turn loop made from 15mm copper tube with a 4.8-meter circumference, operating from 7 MHz to 14 MHz. The document also presents a smaller 800mm diameter loop for 14 MHz to 28 MHz, emphasizing the importance of high-voltage tuning capacitors. Covers the design and construction of custom **butterfly capacitors** and piston capacitors, including a split stator capacitor with 140 pF capacitance and a 6000 Volt rating, and a butterfly capacitor with 5-65 pF and 7200 Volt rating. It explains why butterfly capacitors are preferred over split stator types for high power applications due to lower losses and direct series connection of rotors, reducing resistive losses from wiper contacts. Material recommendations include clear PVC for plates and brass or stainless steel for non-magnetic hardware. Addresses practical considerations such as feeding the loop with a shielded 1/5 Faraday loop made from RG213 or RG8 coax, achieving VSWR 1.1 across bands, and optimizing its placement 180° from the capacitor. It also discusses mechanical joint resistance, dissimilar metal oxidation prevention using Vaseline, and a simple method for determining radiation angle with a TL-light tube. The guide includes diagrams for rotor, stator, and end plate construction.

Simple wire antenna cheap to make, using readily available materials, Low angle radiation, with rejection of high angle signals Wide bandwidth, with resonance at the 80M DX window (3.790-3.800 MHz); and Maximum height is 40 feet

This Vertical antenna design by David Reid for lower bands focuses on achieving effective DX communication by optimizing the antenna low-angle radiation for long-distance contacts. The design incorporates techniques like linear loading and capacity hats to reduce the antenna's height while maintaining performance, especially on 40m and 80m bands. Building a solid ground plane and using quality materials ensure efficiency and durability. Although vertical antennas can be complex to build, this project simplifies the process, making it accessible for ham operators seeking strong, reliable signals.

How High should my Dipole be? Dipole Antennas and the effect of height above ground. The effectiveness of a dipole antenna is influenced by its height above ground, determined by the intended use such as DX work, local communication, directionality, omni-directionality, and feed point impedance. Through EZNEC modeling, the study evaluates a 40-meter dipole's performance at various heights, from 7 to 560 feet. Findings reveal that lower heights enhance omni-directional local communication, while higher placements favor DX work with low-angle radiation. The study emphasizes the importance of defining operational goals to optimize dipole height and performance.

Presents the KE4UYP linear-loaded vertical antenna design, which introduces very little loss on 80 or 160 meters, achieving an overall radiation efficiency of 80% to 85%. This design addresses common pitfalls of traditional base-fed verticals by placing the majority of the current at the top of the antenna, eliminating the heavy reliance on extensive ground radial systems. The author's initial 10-meter model, only three feet tall, yielded 5/9 signal reports to Anchorage, AK, and Europe, confirming its effectiveness. The antenna incorporates both vertically and horizontally polarized radiators, with a 1/4 wavelength horizontal counterpoise located at the feed-point, near the top, to create an almost totally omnidirectional pattern with high wave angle horizontally polarized radiation. This dual polarization ensures even illumination across all take-off angles, making it effective for both local contacts and **DXing**. The vertical element is linear loaded, adding capacitance reactance and making it longer than the horizontal element to achieve resonance and raise the feed-point impedance to 50 ohms. Fine-tuning the antenna requires careful adjustment, as tower reactance can vary. The article suggests starting with 80 feet for 80m and 170 feet for 160m for the vertical wire, then trimming for resonance. Bandwidth specifications include 300 kHz under 2:1 **SWR** on 80m and 100 kHz on 160m when suspended between trees, or 150 kHz on 80m when side-mounted on a tower.

The 80-meter loop antenna, measuring 86 meters (282 feet) of wire, effectively operates across 8 HF bands from 80 through 10 meters, despite its length being a compromise for specific bands. This design prioritizes a "low enough" SWR across multiple bands, aiming for lower SWR values on higher frequencies due to increased feedline losses. A 200-ohm feedpoint impedance provides a workable SWR on every band, with feedpoint impedances ranging from 100 ohms for lower bands to 300 ohms for higher bands. Radiation patterns for the 80-meter loop, mounted at 15 meters high, show a maximum gain of 7.6 dBi at a 90-degree takeoff angle on 80 meters, and up to 12.9 dBi at a 10-degree takeoff angle on 12 meters. This configuration supports regional contacts on 80 meters and provides good DX performance on higher bands. Practical construction notes emphasize using robust supports like trees, ensuring wire slack with _egg insulators_ for wind resilience, and employing an oversized 2 kW 4:1 _balun_ to safely handle higher SWR conditions, even with 100W transceivers. Feedline losses are minimized using _LMR-400_ coax or ladder line, with power transfer efficiency between 80% and 95%. Antenna simulations were performed using _xnec2c_, and the provided NEC file is compatible with other NEC2 derivatives. The antenna is tunable on 6 of 8 bands with an internal ATU and all 8 bands with an external autotuner like the LDG AT-200 Pro.

This drawing shows a simple 10 meter wire J-pole antenna designed for 28.4 MHz. It is a vertical, end-fed Zepp-style antenna made from common materials and intended for easy home construction. The main radiating element is a straight length of stranded copper wire, either 14 or 18 gauge, cut to about 16.5 feet. At the top, the wire is supported by an insulator, allowing the antenna to be hoisted vertically. The matching section is made from 450-ohm ladder line, approximately 7 feet 9.5 inches long, and shorted at the bottom. This matching stub transforms the impedance so the antenna can be fed with coaxial cable. The feed point is tapped about 6 inches above the bottom of the stub, with the shield and center conductor connected at the proper points. A choke balun is formed with five turns of RG-58 coax in a 4-inch diameter loop to help reduce unwanted RF on the feed line. The drawing notes that this antenna has about 0 dBd gain, similar to a dipole, but offers an omnidirectional pattern and low-angle radiation when installed high. Its main advantage is practical performance, simple construction, and effective coverage for 10 meter operation.

A 10-meter J-Pole antenna, detailed in QST February 1950, offers a straightforward solution for hams operating with restricted space. This design, originally presented by W1BLR, is a **half-wave radiator** fed by a quarter-wave matching stub, providing a low-angle radiation pattern beneficial for DX. The article describes building the antenna from readily available materials like copper pipe, emphasizing its simplicity and effectiveness for **single-band operation**. The J-Pole's inherent design provides a good impedance match to 50-ohm coaxial cable without the need for an external tuner, a significant advantage for portable or minimalist stations. Its nondirectional pattern ensures coverage in all directions, making it a versatile choice for general operating on the 28 MHz band. The construction plans are clear, allowing even those with basic workshop skills to assemble a functional antenna.

What is NVIS Near Vertical Incident Skywave. This article on NVIS (Near Vertical Incidence Skywave) explores its role in short-range HF communication, covering 0-200 miles. NVIS utilizes antennas with high radiation angles and frequencies below the ionospheric critical frequency to achieve reliable local contact. He details optimal antennas, like low dipoles, and practical tips for maximizing NVIS performance, emphasizing its advantages such as reduced noise and independent operation without repeaters. However, challenges include frequency sensitivity and the need for appropriate antenna setups at both ends for effective communication.

This antenna project came out very nice. It's a rugged homebrew multi-band trap vertical antenna that works the 10, 15, and 20 meter amateur radio bands. The antenna can be mounted on the ground or on a mast. Mounted on the ground the antenna has a low take off angle for working DX. If mounted on a mast the antenna will acheive both a low angle as well as another radiation lobe that has a much higher take off angle.

A 40-meter reversible _Moxon rectangle_ antenna project details its construction and performance, featuring 51-foot long sides and 7.7-foot turned-in sections. The design incorporates a 16.5-foot boom, with elements spaced 1.1 feet apart, constructed from #14 covered wire. It utilizes two double-pole relays for switching between NE and SW directions, achieving F/B ratios up to 40 dB on CW and 30 dB on SSB, with distinct reflector stub settings for each mode. This antenna replaced a full-size 2-element Yagi, demonstrating comparable forward gain while offering superior F/B ratios and directional flexibility. _EZNEC_ modeling indicates only 0.2 dB less forward gain than the Yagi. The system uses no baluns, relying on half-wave feedlines and switched stubs for impedance matching. The antenna is tree-supported at 45 feet, with its effective radiation height modeled at 80 feet due to local terrain, enhancing its performance over a nearby lake.

Constructing an HF End-Fed Half-Wave (EFHW) vertical antenna, the resource details the winding of a monoband matching unit, inspired by _AA5TB_, designed to provide a 50 Ohm impedance match without a ground plane or antenna tuner. It specifies the use of a _T200-2_ ferrite core for the transformer, outlining the 13-turn secondary and 2-turn primary winding process with enamelled copper wire. The document also describes the integration of a coax capacitor, whose length is critical for tuning and varies by band, with specific starting lengths provided for 20m, 17m, 15m, 12m, and 10m operation. The practical application section guides the builder through tuning the antenna using an antenna analyzer, emphasizing the iterative process of spacing secondary windings and trimming the coax capacitor to achieve resonance at the desired band frequency. It highlights the antenna's low angle of radiation, beneficial for DX, and claims up to 2 S-points improvement over a _G5RV_ or similar doublet when used as an omnidirectional vertical. A comprehensive shopping list, including specific part numbers from _Rapid Electronics_, is provided, along with advice on selecting fiberglass fishing poles for support and suitable antenna wire.

End-Fed Half-Wave Antennas (EFHWAs) are analyzed for their utility in portable QRP operations, emphasizing their simplicity, efficiency, and predictable radiation patterns compared to other portable antenna types. The discussion contrasts EFHWAs with vertical antennas, random length wires, and center-fed dipoles, highlighting the common pitfalls of each, such as ground system dependency for verticals and feedline issues for dipoles. The article details the electrical half-wavelength calculation using the formula L (Ft) = 468/F(MHz) and explains how EFHWAs can be resonant on harmonic frequencies, enabling multiband operation. Various deployment configurations are presented, including the inverted L, inverted Vee, sloping wire, and vertical setups, each with specific advantages for radiation angle and polarization. For instance, a vertical EFHWA offers a low angle of radiation suitable for DX contacts without requiring an extensive ground system. The resource also addresses the counterpoise requirements, suggesting a quarter-wavelength wire or connection to a metallic structure for decoupling. A schematic diagram for a simple parallel-tuned circuit tuner, based on the _Rainbow Bridge/Tuner_ design, is provided, detailing component values for 30 and 40 meters, including a 6 microhenry toroidal inductor and a 20-100 picofarad mica compression capacitor. The tuner's adjustment process for SWR matching is also outlined.

Portable Vertical Antenna for 75m and 40m featuring Low radiation angle for DX, easy to install and to match 50 ohms

Simple, inexpensive and easy to erect, this antenna provides directivity, low angle radiation and a small gain on a number of HF bands.

A Compact size 80-10 m field day antenna offering a Low angle of radiation and very easy to build and set up

21 mhz half wave ant -very low radiation angle - full size and light weight- all coax matching system - decoupling care to prevent low angle radiation degrade

A 20-meter Moxon antenna design provides a compact directional solution for the 14 MHz band, achieving approximately **5.5 dBi** of forward gain and a front-to-back ratio exceeding 20 dB. This rectangular wire array, consisting of a driven element and a reflector, offers a smaller footprint than a traditional 2-element Yagi, making it suitable for space-constrained installations. Construction details focus on specific dimensions for the wire elements, fed with 50-ohm coaxial cable. The _Moxon rectangle_ inherently delivers wide bandwidth and a clean radiation pattern, simplifying tuning with a relatively low SWR across the entire 20-meter band. Its robust performance makes it a practical choice for both fixed stations with limited tower space and portable _DXing_ operations. The design's characteristics are particularly beneficial for contesting and long-haul communications on 20 meters.

The resource provides an in-depth analysis of the W6NL 40m _Moxon Yagi_ antenna, utilizing a NEC-2 model to simulate its performance. It details the antenna's design parameters, including element lengths and spacing, and explores critical operational aspects such as feedpoint impedance, SWR across the 40-meter band, and radiation patterns. The document systematically presents the model's setup and the methodology for evaluating the antenna's behavior in different environments, including free space and over real ground. Performance data derived from the NEC-2 model illustrates the antenna's forward gain, front-to-back ratio, and beamwidth. For instance, the model predicts a free-space gain of approximately **6.5 dBi** and a front-to-back ratio exceeding **20 dB** at resonance. Comparisons are drawn between free-space performance and operation at various heights above average ground, demonstrating the impact of ground proximity on take-off angle and overall efficiency. The analysis also touches upon the antenna's bandwidth characteristics, indicating its suitability for the entire 40-meter band with acceptable SWR.

Very compact and high efficiency antenna ,very low radiation angle even at low height.

This strange looking antenna is a combination of Coupled-Resonator principle by K9AY and a quarter stubs to achieve low angle radiation pattern. Designed with 4nec2 NEC based antenna modeler and optimizer for 145/220/440MHz bands

Antenna mounting height, the higher the better? Learn how radiation pattern change, and decide if you need an higher or a lower angle for your dx needs.

A 20-meter vertical _Moxon_ antenna, designed for portable operation, is detailed with specific dimensions for its driven and reflector elements. The project outlines the construction process, including the use of PVC pipe for the frame and #14 AWG insulated wire for the elements. The antenna's compact size and directional characteristics make it suitable for field day operations or limited space environments, offering a gain of approximately 5.5 dBi and a front-to-back ratio of 20 dB. Testing revealed a 1.2:1 SWR at 14.250 MHz, demonstrating good impedance matching across the target frequency range. The _Moxon rectangle_ design provides a clean radiation pattern with minimal side lobes, which is advantageous for reducing QRM from unwanted directions. This build offers a practical solution for hams seeking a lightweight, easily deployable directional antenna for 20 meters without the complexity of a full-sized Yagi.

This 4m Slim Jim Antenna is cheap and easy to build yet it greatly out performs the more usual dipole due to its low angle of radiation. An SWR of 1:1 is obtainable across the 4m ham radio FM band with a simple adjustment.

Nowdays lots of people are putting up antennas to either beam in different directions at the same time or just to stack them and get a lower angle of radiation. Use this stackmatch to match you array.

A bowtie antenna is a type of antenna that reputedly provides higher gain at lower radiation angles than a center-fed dipole antenna at heights considerably less than 1/2 wavelength above ground.

Presents the construction of a 6-meter (50 MHz) Moxon wire beam antenna, detailing the use of #14 AWG THNN stranded wire and a treated wood frame. It covers the assembly of a galvanized pipe mast, emphasizing the use of pipe sleeves for joint reinforcement over threaded couplers to prevent breakage during raising and lowering operations. The resource also describes the integration of a 1:1 current balun, rated for 50-54 MHz, and the use of RG-8X coax for the transmission line, recommending low-loss alternatives like Belden 9913-7F. Further, it outlines a manual rotation mechanism using pipe hanger clamps and carriage bolts for true North orientation, incorporating magnetic declination calculations from NOAA. The antenna's performance is discussed, noting good gain and take-off angle, with SWR tuning facilitated by a Palstar AT-500 manual tuner. An EZNEC+ 5.054 model for the antenna is available for download, alongside predicted radiation patterns and SWR curves, compared with actual AIM-4170C measurements.

Examining the _Angle of Radiation_ and its impact on amateur radio operations, the resource provides insights into optimizing antenna performance for DX and local contacts. It features a design for SPOTTO, a direct conversion high-performance universal DSB transceiver, detailing its construction and operational characteristics for homebrew enthusiasts. Additionally, the site presents a 7-element VHF high-gain antenna design, offering practical schematics and expected performance metrics for those seeking enhanced gain on VHF bands. The resource also covers the development and popularity of the _FT8_ digital mode, highlighting its effectiveness in weak-signal conditions and its role in special event operations like the FT8DMC anniversary. It includes information on Hamfest India 2023 and the Lamakaan Amateur Radio Convention, providing dates and organizational details for significant Indian amateur radio gatherings. Technical articles on Direct Digital Synthesizers (DDS) VFOs and low-cost multifunctional frequency counters offer practical project ideas for radio amateurs.

Troposcatter, 50 MHz meteor scatter, ground gain for eme, radiation angle, by OZ1RH

The NB6Zep Antenna, an electrically shortened 80-meter end-fed wire, addresses space constraints for low-band operation by integrating two loading coils into a 37-foot wire. This design, modeled with _EZNEC_, explores configurations like the quarter-wave sloper and inverted-L, with the latter providing a more vertical radiation pattern and practical backyard deployment. The resource details specific coil construction, recommending 21 uH coils made from _BW coil stock #3026_ or similar, and outlines wire segment lengths for optimal tuning. Performance analysis indicates a radiating efficiency of approximately 27% with good ground conductivity, resulting in a signal typically 3-4 dB down compared to a full-size quarter-wave vertical. The antenna exhibits a narrow bandwidth, around 50 kHz, due to its high Q, necessitating a tuner for broader band operation. Feedpoint impedance is low, with ground resistance playing a critical role in achieving a usable SWR. The article emphasizes the importance of an effective ground rod at the feedpoint for proper operation and tuning, suggesting an antenna analyzer for precise adjustments. It confirms the antenna's suitability for DX, citing successful contacts from Oregon to the East Coast and Hawaii on a 160-meter variant, making it a viable option for urban operators seeking low-angle radiation on 80 meters.

The advantage of 5/8 wave antenna is that it has the lowest angle of radiation and has about 1dB more gain when compared to 1/4 and 1/2 verticals. So the 5/8 should be the favourite choice for DX.

NVIS antennas, also known as Near Incident Vertical Skywave antennas have a high angle of radiation. Something on the order of 60 degrees, to straight up to 90 degrees. A portable, easy to setup and cheap nvis antenna project.

Constructing a compact directional antenna for the 17-meter band, this resource details the build process for a Moxon rectangle, a two-element Yagi variant with folded-back elements. It covers the antenna's evolution from the _VK2ABQ beam_ and provides specific dimensions for a version built using fishing pole whips. The content includes a discussion of the antenna's radiation pattern, feedpoint impedance, and its inherent front-to-back ratio, which is often superior to a standard two-element Yagi. Practical considerations for element spacing and material choices are also addressed, alongside a visual representation of the antenna's physical layout. Performance data presented includes a comparison showing the Moxon rectangle's **2.5 dB gain** over a half-wave dipole and a front-to-back ratio of **20 dB**. The resource also touches upon the antenna's relatively wide bandwidth for a two-element beam and its suitability for portable operations due to its compact footprint. It offers insights into optimizing the design for specific operating conditions and discusses the advantages of its lower take-off angle compared to omnidirectional wire antennas, making it effective for DX contacts on the 17-meter band.

A monoband delta loop antenna for the 7 MHz. This vertically polarized DX Antenna is a full wavelength sngle side antenna and has a total length of 42.3 meters (137,1 inch) Can be easily setup with a flag pole or fishing pole as center top mast. For optimal performance lower side should be at 2 meter above the ground. This antenna offers a low radiation angle and 1 DB Gain.

The Tri-pole antenna, a clever modification of a standard dipole, allows for dual-band operation by integrating a third element. This design effectively shortens the overall dipole length by 10 to 20 percent, simplifying antenna rotation and offering a compact footprint. KK4OBI's article delves into the operational principles, using a 6 and 10-meter Tri-pole as a primary example, and provides comprehensive instructions for constructing any Tri-pole antenna within the 6 to 15-meter range. Key to the Tri-pole's performance is its off-center feed, necessitating a common mode choke at the feed point for optimal tuning and reduced noise. The author outlines a methodical approach to determining element dimensions, starting with a vertical element frequency calculated as 0.47 times the sum of the desired upper and lower band frequencies. This calculation, along with K-values derived from trend lines, guides the initial lengths for the horizontal arms, demonstrating how a 10m-6m Tri-pole can achieve a total horizontal length 78% shorter than a conventional 10-meter dipole. Tuning and balancing are critical, with the article detailing adjustments to arm lengths and the vertical element to achieve balanced SWR values, as validated through 4NEC2 simulations. Radiation patterns are analyzed at various elevations, showing gains around 5.7 dBi and favorable take-off angles for DX contacts. Construction details specify aluminum tubing dimensions, U-bolts, and an SO-239 connector, emphasizing the importance of a ferrite-based choke for wideband operation.

Make them simple then Make them work. The LAZY H antenna is a general type of antenna that is in the curtain array family. By placing two 1 wavelength dipoles in a plane that is at right angles to the direction of maximum radiation and keeping the proper in-phase current condition to each element, you can achieve a high gain bi-directional antenna.

This page delves into the Inverted V antenna, a source of myths among ham radio operators. The author explores the behavior of this antenna type with a focus on a 20m half-wave dipole positioned 10m above the ground. From Pythagoras to high school math, the article simplifies the calculation of dimensions and angles for setting up an Inverted V antenna. It includes a spreadsheet for calculating hypotenuse length and angles, crucial for antenna setup. Additionally, it provides insight into the radiation pattern of a 'flat' half-wave dipole at 10m height. Useful for hams planning to optimize their antenna setup. In Norwegian.

Constructing a directional antenna for VHF operations, particularly for 2-meter band contests or local communication, often involves balancing performance with ease of build. The Moxon rectangle, a compact two-element beam, offers a good front-to-back ratio and gain in a smaller footprint compared to a Yagi, making it suitable for portable or temporary setups where space is limited. This design typically uses a driven element and a single reflector, bent into a rectangular shape to achieve its unique radiation pattern. The article details the construction of a 2-meter Moxon antenna, specifically for 144 MHz, utilizing readily available materials like PVC pipe for the frame and copper wire for the elements. It outlines the dimensions for the driven element at 970mm and the reflector at 910mm, with a spacing of 140mm between them, and a 50mm gap at the element ends. The feedpoint is a direct 50-ohm connection, simplifying matching requirements. The project includes a parts list, a basic diagram illustrating the element layout and dimensions, and photographs of the completed antenna. The author notes the antenna's performance during a QRP contest, achieving contacts up to 100km with 5 watts, demonstrating its effectiveness for low-power VHF work.

The article describes the construction of a Lindenblad antenna, which is well-suited for receiving signals from low-orbiting weather satellites. The key points are: The Lindenblad antenna has an omnidirectional horizontal radiation pattern and is optimized for low to medium elevation angles, making it ideal for tracking passing satellites near the horizon. It is designed to receive circular polarization, which is common for weather satellite signals. The antenna is constructed using 4 folded dipole elements arranged on a cross-shaped frame. The necessary materials include a plastic junction box, PVC tubing, and aluminum rods to form the dipole elements. The article provides detailed instructions for preparing the components, assembling the dipoles, and connecting the feed lines to create the complete antenna. The completed antenna can be mounted on a vertical support, with the dipole elements angled at 30 degrees from horizontal, to optimize reception of the passing satellites. The author notes that the design was originally published in a now-defunct magazine, Meteo Satellite Inf", in 1993

7MHz to 30MHz operation is achieved with a magnetic-mounted HF antenna designed for car roof deployment, capable of handling 100 Watts without an external antenna tuner. The design incorporates a large base-loading coil with multiple taps, allowing for frequency selection across various HF bands. This coil effectively increases the electrical length of a short telescopic antenna element, compensating for its inherent capacitance. Construction involves 3D-printed components for the coil former and support structures, though conventional building methods using plastic drainpipes are also suggested. The car body serves as the ground plane, with the coil assembly mounted on a 500mm square metal plate secured by super neodymium magnets. Protection under the magnets is advised to prevent vehicle scratches. Detailed instructions cover winding the 30-turn coil with 2.5mm diameter household electrical cable, assembling the 3D-printed parts, and making soldered connections. Taps are staggered every five turns for precise frequency adjustment. Performance examples include a 7913km contact to Japan using a 1.5m element and 100 Watts, demonstrating low-angle radiation and omni-directional pattern with minimal S-point loss compared to a full quarter-wave.

This article focus on the radiation angle of vertical antennas and the fundamentals of electromagnetic wave propagation. The calculation of antenna length at 145 MHz is followed by an explanation of electromagnetic wave speed and the link between wavelength, frequency, and velocity. Author discusses the 5/8th wave vertical antenna, namely its performance and the influence of radiation angle on signal transmission. Figures and analogies demonstrate how different antenna types produce distinct radiation patterns. This highlights the importance of selecting the right antenna for a certain purpose, such as local traffic or dxing. The article discusses a variety of factors that affect antenna performance, including SWR, propagation conditions, and equipment dependability

High Frequency (HF) radio propagation, particularly the phenomenon of "Skip," which enables long-distance radio contacts, is thoroughly explained for newcomers to the amateur radio hobby. The article begins by defining essential terms such as _radio signal_, atmosphere, troposphere, stratosphere, mesosphere, thermosphere, exosphere, and aurora, setting a foundational understanding for subsequent discussions. A significant portion of the content focuses on the ionosphere, identifying it as the primary driver of HF propagation. Its structure, including the D, E (E1, E2, E3), and F (F1, F2) layers, is detailed, along with how solar radiation influences these layers to refract radio waves back to Earth. The concept of "The band is opened!" is introduced, specifically noting refraction around **21 MHz**. The guide also touches upon ground waves, space waves, and temperature inversions affecting VHF/UHF propagation, contrasting them with the dynamic nature of ionospheric HF propagation. Factors like antenna polarization, takeoff angle, and the sun's solar cycle are mentioned as critical influences on signal path, with examples like 80-meter band propagation after sunset and 40-meter/20-meter bands offering near-constant propagation.

Understanding radio wave propagation is fundamental for effective HF communication, and this guide from the Galway Radio Club elucidates the principles behind _Near Vertical Incidence Skywave_ (NVIS) operation. It begins by contrasting NVIS with line-of-sight and surface wave propagation, highlighting its utility for reliable regional coverage, particularly in challenging terrains or within the skip zone. The document explains how NVIS leverages high-angle radiation, refracting signals from the ionosphere to return to Earth within a circular region, typically up to **650 km** (400 miles) from the transmitter. The guide delves into critical factors influencing NVIS, such as the _critical frequency_ (Fo) and the Maximum Usable Frequency (MUF), emphasizing their dependence on solar activity, time of day, and season. It provides practical advice on frequency selection, noting that 40 meters is often the highest daytime NVIS band, with 60 meters and 80 meters favored as darkness falls. The author, EI5DD, suggests using an ionogram for real-time propagation data, considering it more reliable than generic ham-clocks. Antenna considerations are also covered, recommending dipoles, inverted vees, or phased dipoles positioned 0.1 to 0.25 wavelengths above ground for optimal high-angle radiation. The document mentions mobile NVIS setups, including military configurations and commercial options like the Barrett Communications roof-rack antenna, which can cost around **£2000.00**. It concludes by reinforcing NVIS as an essential technique for national emergency communications, with 5 MHz (60m) and 80 meters being primary bands for daytime and nighttime operations, respectively.

A full-wave delta loop antenna, approximately 141 feet in total wire length for the 40-meter band, offers a low angle of radiation, which is highly advantageous for DX operations. This design, optimized for both 30m and 40m, leverages a specific circumference calculation of 1005/F, ensuring resonance on both bands through a simple switching mechanism. The antenna's configuration enhances long-distance communication, making it a practical choice for hams with limited space. The resource details the construction process, including the use of a _Ceramic Knife Switch_ for band selection and an _RG-11_ matching section to achieve optimal impedance. It outlines the precise loop lengths required for each band, along with tuning secrets to ensure efficient operation. Requiring a minimum height of 12 feet, this antenna can be supported by a single mast or tree limb, making it suitable for suburban installations where stealth or space constraints are a factor.

Demonstrates the design and modeling of a **160m** vertical antenna, dubbed the "WindoVert," specifically for urban amateur radio operators with limited space. The resource covers the theoretical underpinnings of antenna height and radiation patterns, using EZNEC software to analyze current distribution and 3D radiation patterns for various configurations, including a Marconi-style "T" antenna. It details the integration of existing antenna components, such as a Carolina Windom balun and line isolator, into the new vertical setup, and the practical measurement of feedpoint impedance using an antenna analyzer. The article further explores the challenges of achieving low-angle radiation on Top Band, emphasizing the critical role of radial systems and mitigating ground loss. Author VE1ZAC presents EZNEC models illustrating the impact of lumped components and discusses the practical considerations of resonant frequency adjustment and impedance matching for **QRP** operation. The text details the calculation of required loading coil inductance and capacitance, and shares field results, including successful DX contacts on 160m and unexpected excellent performance on 30m.

This article discusses the Beverage antenna, a reception antenna for low bands, originally published in the Megahertz magazine between November 1990 and April 1991. It explains the challenges faced in receiving signals on low bands due to interference and how the Beverage antenna's directional radiation pattern can help improve reception of distant stations. The article highlights the importance of choosing antennas with low efficiency but sharp radiation lobes for better DX signal reception. It also compares the reception characteristics of signals from European stations versus DX stations, emphasizing the benefits of antennas favoring low arrival angles for DX signals on low bands.

The 4m Slim Jim antenna project provides a construction guide for a low-cost, high-performance aerial designed specifically for the 70 MHz FM band. This design achieves a 1:1 SWR across the 4m FM band with straightforward adjustment of the feed point, utilizing RG-58 coax. Its low angle of radiation contributes to effective signal propagation. Construction involves using plastic knitting needles as spreaders and a telescopic fishing pole for support, with components secured using two-part epoxy. Annealed bare single-core copper wire forms the radiating element. The setup process includes raising the antenna at least 3 meters above ground for tuning, adjusting the RG-58 feed point for optimal SWR, and then soldering connections. Waterproofing is achieved with yacht varnish. The design emphasizes low wind resistance for durability, making it suitable for exposed outdoor installations. A PDF construction diagram is available to supplement the written instructions.