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WB8LZR details the construction and initial field results of a multi-band vertical wire antenna, designed to complement his existing horizontal loop for improved DX on 80 meters. The antenna utilizes a 67-foot vertical wire, configured as a quarter-wave radiator on 80m, and employs a 1:1 current balun for RF isolation on 80m, 30m, and 17m. For bands like 40m, 20m, and 10m, where the wire acts as a half-wave or full-wave radiator, an additional impedance transforming _unun_ is integrated to manage the significantly higher feedpoint impedance and voltage. The author notes the vertical's performance as a receiving antenna, observing reduced noise compared to his main horizontal loop, particularly on 80m, and even hearing some long-path signals the loop missed. Initial QRP contacts, including a **1-watt** QSO with a _VP2 station_ on 30m, demonstrate its transmit capability. While the radial system is currently rudimentary, the project outlines practical considerations for multi-band vertical deployment and impedance matching.

Intrigued by a German OM positive experience with a 20m delta loop, the author replicated the design, noting its favorable 50-ohm impedance compared to their 40m version. Testing against a vertical EFHW, the delta loop excelled within EU but lagged at longer distances. Despite needing more testing, the user leaned towards the EFHW for its overall performance and practicality.

This PDF document provides detailed information on small loop antennas for hams. It covers the design, construction, and usage of small loop antennas for amateur radio operators. The guide includes practical tips and recommendations for optimizing the performance of small loop antennas in various operating conditions. Whether you are a beginner or an experienced ham radio operator looking to improve your antenna setup, this guide has valuable insights to offer.

Learn how to build a simple tuned loop antenna for the AM broadcast band to improve the performance of your radio receiver. Discover how to construct a loop antenna with readily available materials, such as balsa and basswood, without the need for specialized woodworking tools. Follow step-by-step instructions to create a portable loop antenna that offers good gain and directivity, ideal for pulling in weak stations. Enhance your Ultralight DX'ing experience and explore the world of FSL antennas through this practical DIY project.

An homebrew HF Magnetic loop made with 2m length of 6mm diameter copper pipe formed into a near circle as the low loss inductor, a short length of coax as a capacitor,a short length of mains cable, again as a fixed tuned capacitor, a tunable 365pF air spaced capacitor, and a small Jackson C804 airspaced variable with a small 3-35pF trimmer in parallel

A KiwiWebSDR from Siliguri West Bengal India running a W6LVP loop antenna for HF Bands

An cheap and efficient wire antenna for lower HF bands. This closed loop antenna, radiates perpendicular to its plane with a bi-directional radiation pattern. With a gain of 2 dB over a diplole it is a low noise sensible antenna. Requires a tuner if you want to use as a multiband antenna.

This study details a reception comparison between vertical and horizontal active loop antennas, specifically two identical _Wellgood active loop antennas_, on various HF bands. The experiment, conducted in a densely populated QRM-prone area, monitored FT8 signals over a 24-hour period using two identical receivers. The methodology involved direct comparison of signal reception across the HF spectrum, aiming to identify performance differences based on antenna orientation. The results indicate that vertical loops demonstrated superior performance on higher bands (10m, 15m, 20m), while horizontal loops excelled on lower bands (30m, 40m, 160m), particularly for receiving long-distance (DX) signals. The horizontal loop's advantage on lower bands is attributed to potentially better low-angle performance and reduced sensitivity to man-made noise, yielding a **2-3 S-unit** improvement on 160m. The study provides practical insights for optimizing antenna placement in challenging urban environments, noting that the horizontal loop consistently showed a **10-15 dB** signal-to-noise ratio improvement on lower bands.

The high-frequency inductance of single-turn loops of various shapes made of round wire can be estimated accurately with a simplified formula

Learn how to build a portable receiving antenna for the 160 meter band. This guide provides detailed instructions on constructing a loop antenna using a coaxial cable RG-316 with SMA connectors. The antenna weighs 1.7 kg and has dimensions of 2m in height and 1.892m in width. The wooden frame consists of four 0.945m long pieces and two 1m long pieces. Perfect for hams looking to enhance their 160m band reception during travel or portable operations.

Discover the best low band receive antennas for hams with limited space. Learn about the K9AY loop antenna and Shared Apex Loop Array, two alternatives to the traditional Beverage antenna. Understand the concept of Relative Directivity Factor (RDF) and compare the performance of different receive antennas. See how the Shared Apex Loop, patented by Mark Bauman (KB7GF), offers an RDF between 8 and 10dB. Find out how to optimize antenna performance and enhance your receive capabilities on 160, 80, and 40 meters. Explore the world of low band receive antennas with insights from WB5NHL Ham Radio.

The Score Distributor facilitates real-time score forwarding for amateur radio contests, automatically transmitting data from various logging software to multiple online scoreboards. By configuring logging applications to send score data to the Distributor, operators ensure their current score is simultaneously represented on platforms like the _Contest Online ScoreBoard_ (COSB) and the Live Contest Score Server by R4WW. This system eliminates the need to choose a single scoreboard, providing broader visibility for participants. This utility enhances the competitive experience by allowing contesters to monitor their performance against other stations throughout an event. Observing real-time standings can provide significant motivation, particularly during periods of challenging propagation or when striving to maintain pace with club members or peers. The platform supports almost all major contest logging software, simplifying integration for a wide range of operators. Developed by WA7BNM, the Score Distributor was last revised on June 14, 2023. It aggregates score data, offering a unified point of submission that then disseminates the information, ensuring a **single point of entry** for broad scoreboard coverage and improving the dynamic feedback loop for participants.

Setting up a portable wire delta loop antenna with an MFJ 33ft telescopic fiberglass pole

Demonstrates the construction and portable deployment of a 40-meter horizontal loop antenna, often referred to as a "Sky Loop" or "DX-Buster." The design adapts a full-wavelength horizontal loop for field use, eliminating the need for traditional insulators by employing four 5-meter heavy-duty _squid poles_ and metal post bases for support. This setup facilitates rapid assembly, crucial for portable operations, with the antenna wire length specified at approximately 43-45 meters for optimal 40-meter band performance. The resource details the specific construction methodology, including winding the antenna wire around rubber caps on the squid poles and securing it with electrical tape. It provides a parts list and assembly techniques, focusing on minimizing components for ease of transport and quick setup. The article, originally published in the February 2013 edition of the Central Coast ARC "Smoke Signals" magazine, reflects practical experience. This documentation offers a field-deployable 40-meter loop antenna solution, utilizing readily available components like fiberglass squid poles. It presents a practical approach for operators seeking a robust, portable antenna for the 40-meter band, emphasizing simplicity and efficiency in its design and deployment.

This is a 50 MHz WebSDR receiver, located in Ashford, CT, USA FN31VU using a deltaloop turnstile horizontally polarized omnidirectional antenna.

This article details a ham radio operator’s experience setting up HF antennas in an antenna-restricted community. Initially using an AEA Isoloop magnetic loop for QRP PSK, the author later built an attic antenna system, including dipoles for multiple HF bands and a slinky dipole for 40 meters. The setup allowed for operation on six bands with acceptable VSWR. Despite space constraints and some compromises, performance was effective. The article highlights practical strategies, emphasizing experimentation and antenna modeling for optimizing performance in limited-space environments. A valuable guide for ham radio operators facing similar restrictions.

This page provides a detailed guide on how to build your own radioless Allstar node for ham radio operators. It includes information on power supply, components needed, wiring instructions, and tips to avoid common issues like ground loop hums. The author shares personal experiences and recommendations for specific components like microphones, audio amps, and sound fobs. Whether you're a beginner or experienced ham radio operator, this DIY project can help you set up a cost-effective and functional Allstar node for communication purposes.

The latest version of the K1FM-Loop is electrically similar to the previous one, but it is designed around off-the-shelf parts or, more generically, items you can readily order online. This antenna relies heavily on 3D printing.

Discover the success story of creating a 4-meter Delta Loop antenna, ideal for improving radio communication. This horizontally polarized antenna offers efficient performance when mounted at VHF heights, catering to both HF and VHF characteristics. A simple, DIY project suitable for portable setups, providing versatile options for radio enthusiasts.

This page allows hams to design a vertical-plane delta-loop antenna for a single amateur HF band in different configurations. By choosing different feed-point positions, operators can observe variations in polarization properties, radiation patterns, and feed-point impedances. Users can generate radiation pattern plots, VSWR charts, antenna current diagrams, and Smith charts for their antennas over various ground types. Through adjusting the antenna's physical dimensions and refreshing the plots, hams can gain insights into the antenna's performance in the field. The page also discusses how elevation radiation patterns may change based on the antenna configuration and feed-point position.

This article provides an in-depth review of the Ciro Mazzoni Baby Loop Ham Radio Antenna. The author, a ham radio operator, compares this magnetic loop antenna with his usual End Fed Half Wave antenna, discussing the performance and installation considerations. The post explains the concept of loop antennas, resonating frequencies, and the benefits of using a small loop antenna with a capacitor for optimal operation. If you are looking for information on magnetic loop antennas and their effectiveness in restricted spaces, this review offers valuable insights and practical experiences for ham radio operators.

Unveil the secrets of efficient Magnetic Loop Antenna control systems, eliminating the hassle of frequent retuning. With real-time tracking and compatibility with various transceivers, including popular models from Elecraft, ICOM, Kenwood, and Yaesu, this controller ensures seamless frequency adjustment. Explore its high-resolution stepper motor and versatile communication capabilities, revolutionizing amateur radio operation.

A vertical delta loop is a practical antenna for low bands, popular for its simple design requiring just one support. Its shape, an equilateral triangle in free space, yields optimal gain and radiation resistance. Deviating from this shape lowers performance. The delta loop can be polarized either horizontally or vertically based on the feed point location. In vertical polarization, it acts as two quarter-wave verticals with the baseline feeding one side. This design minimizes radiation from the baseline while maintaining effective operation.

Learn how to design a Hentenna antenna, a portable asymmetrical double-loop antenna ideal for amateur HF or VHF bands. This page provides details on constructing and optimizing the antenna for maximum performance in DX communications. Discover how altering the antenna's vertical feed section can adjust the VSWR resonant frequency and how changing the support pole's position can alter the beam direction. Originally developed by Japanese 6-meter operators, the 'Hentenna' offers a unique design that allows for horizontal polarization when vertically oriented. Explore radiation patterns, VSWR charts, and antenna currents diagrams to optimize your antenna's performance for long-distance contacts.

The tri-band trapped delta loop antenna design operates on 80 meters (3.5–4 MHz), 40 meters (7–7.3 MHz), and 30 meters (10.1–10.15 MHz) using a single triangular wire loop. This configuration eliminates the need for an external antenna tuner or band-switching relays. The antenna's physical perimeter, approximately 270 feet, establishes 80M as the fundamental band, with specific trap placements enabling resonance on 40M and 30M. Trap design and placement are critical, with 30M traps positioned inboard of 40M traps within the horizontal element. Each slant leg measures approximately 80 feet. The resource references foundational information from the _ARRL Antenna Handbook_ and _ON4UN’s Low Band DXing_ regarding full-wave loop behavior and feedpoint impedances. The project aims to provide multi-band HF operation from a single, fixed antenna structure.

Delta loop antennas, particularly the 30 meter variant, offer unique advantages in terms of vertical polarization and omni-directional coverage. The construction process detailed by VE3VN highlights common mechanical and electrical challenges faced by amateur radio operators. Key design considerations include minimizing interaction with existing contest band antennas, achieving low elevation angles for DX chasing, and ensuring the antenna remains off the ground for agricultural clearance. The article provides specific measurements, such as the loop's height and feed point impedance, which are critical for optimizing performance. The use of NEC modeling software illustrates the importance of accurate resonance calculations, revealing how proximity to the tower affects both pattern and impedance. This practical account serves as a resource for hams looking to build effective antennas while navigating typical construction hurdles.

OM0ET manufacture high capacity variable air capacitor and tuning unit designed for Magloop antennas. OM0ET explains features and benefits of this antenna, such as easy assembly, wide frequency range, and improved efficiency. Ideal antenna setup for indoor or outdoor use, offering better QSO performance and radio listening experience. The author, identified as OM0ET, shares insights on the design and functionality of the equipment, making it a valuable antenna for portable operations.

This resource details the construction and performance of a compact broadband magnetic loop antenna designed for portable receiving applications with devices like the _ATS MiniRadio_. The antenna utilizes approximately 3 meters of 0.5–1 mm copper wire wound in two turns on a rhomboidal wooden frame, measuring 50 cm by 70 cm. It connects via a modified 9:1 unun, where the primary center tap is isolated from ground to improve common-mode noise rejection. The design provides untuned operation across a frequency range from the longwave band up to approximately 25 MHz. Performance characteristics include observable directivity for noise suppression and the ability to connect directly to a radio or via a 50 coaxial cable for remote operation. The article specifies the unun's 3:1 turns ratio and its SMA output for connectivity. The methodology focuses on practical construction and observed reception quality.

This presentation on antennas is a practical guide for amateur radio operators. The key takeaway is that the best antenna for your station depends on your constraints and goals. There is no magic solution and buying a wire antenna is not recommended as it might be expensive and not as effective. The presentation covers different antenna types including dipoles, verticals, Yagis and loop antennas. Important factors to consider when choosing an antenna include SWR, feeder types, and whether you need a balun. The author emphasizes that ATUs don’t improve a poor antenna and advises against obsessing over SWR readings.

Chavdar Levkov, LZ1AQ, presents an experimental comparison of small wideband magnetic loops, building on his previous work on wideband active small magnetic loop antennas. His research focuses on increasing loop sensitivity by maximizing the short-circuit current, which is directly tied to the "loop factor" M = A/L, where A is the equivalent loop area and L is its inductance. Levkov's methodology involves reducing inductance and increasing area through parallel or coplanar crossed (CC) configurations, comparing these designs against a reference single quad loop of 1 m2 area. Experimental verification included testing three distinct loop types: a simple quad loop, two coplanar crossed (CC) loops, and eight parallel loops, all designed to have a total geometric area of 1 m2. Measurements were conducted at 1.8, 3.5, 7, and 10 MHz using a small transmitter 270 meters away, with a Perseus direct sampling receiver for precise signal level assessment. The results consistently showed that CC loops, particularly Loop 5 (two CC circular loops with 1.44 m2 total area), yielded significantly higher currents, up to 9.1 dB over the reference loop at 3.5 MHz, validating M as a reliable predictor of loop sensitivity. Numerical simulations using MMANA further corroborated the experimental findings, demonstrating an almost perfect correlation between the calculated M factor and the induced loop current for 15 different loop models. Levkov concludes that CC loops offer superior sensitivity for a given loop area, while parallel loops are advantageous for minimizing physical volume. Practical recommendations suggest using loops with an M factor greater than 0.5 uA/pT for quiet rural environments, and he provides a spreadsheet tool, WLoop_calc.xls, to aid in optimizing loop configurations for specific operational needs.

Building some proper matching transformer for loop on ground and Beverage antennas

The Aziloop DF-72 antenna system provides 72 K9AY headings and 36 loop axes, allowing for rapid switching in 60 ms. It integrates a switchable 18 dB preamp, a 4-step attenuator (0-18 dB), and four 7-pole preselection filters to optimize receiver performance. The K9AY load is adjustable from 250 Ohm to 950 Ohm in 50 Ohm increments, offering flexibility for various receiving conditions. Control is managed via an intuitive Windows UI, supporting Local, Client, or Server modes, with headless remote operation possible through the built-in Ethernet Server. _Omni-Rig_ support facilitates auto-filter selection, PTT muting, and Rig-Sync functionality, enhancing integration with existing station setups. Designed by _GW4GTE_, the system utilizes a low visual impact, small-footprint antenna with orthogonal loops and an earth connection. It is suitable for general monitoring, co-channel station resolution, basic direction finding, and interference reduction across the VLF to HF spectrum.

The small receiving loop (SRL) is a versatile and efficient antenna that can be simply built from common materials. It is designed for reception on the MF and HF bands and may be put in a variety of shapes and sizes. Despite its unusual installation, the porch loop in this case operated admirably, producing several DX spots on the 40m band. The SRL can be a great option for people looking to boost their reception on the MF and LF bands.

This loop antenna is intended to be connected as an antenna for receivers that do not have a built-in antenna such as an HF set or an old tube radio. This square barrel is wound on a wooden frame. It consists of two windings that are galvanically isolated from each other, a main and a coupling winding. The diameter is about 40 cm.

A detailed guide presents a simple 2-element quad antenna for 2m, offering ease of construction, portability, and efficient performance across the 144-148 MHz band. The design allows quick disassembly for storage and features adjustable polarization, making it ideal for various applications, including transmitter hunting and SSB operations.

Cloverleaf antenna is a circular polarized antenna which is way better than the cheap dipole antenna that comes with video transmitters and receivers. The Cloverleaf is a closed loop antenna which the signal and ground wires are connected. The cloverleaf antenna has 3 loops at 120 degree apart, and they are titled at 45 degree to horizontal plane.

The F6AOJ RX splitter project was created to split the antenna signal from an LZ1AQ receive loop to multiple receivers, such as radios or SDRs. The design is simple to build and effective. The splitter, mounted on the back of the LZ1AQ control board, provides two outputs—one for an Afedri SDR and another for a K3 transceiver. Measurements show a damping of -3.01 dB at 1 MHz and -3.10 dB at 30 MHz, with a low SWR (max 1.07 at 30 MHz and 1.4 at 60 MHz).

Integrating a _Software Defined Radio_ (SDR) into an existing ham radio setup involves connecting it with a standard transceiver (TRX), power amplifier (PA), and antennas. The core component is a splitter box that facilitates the connection between the TRX and the SDR, allowing for simultaneous operation without modifying existing equipment. In receive mode, the splitter ties the antenna inputs of both the TRX and a direct conversion receiver (DC RX) together. During transmission, the DC RX input is grounded via a fast telecom relay controlled by the transceiver's -SEND signal, incorporating a 10ms delay for safety. The splitter box includes a 3.7 dB input attenuator for impedance matching and acts as a protective fuse for the DC RX input. Ground loops are mitigated using common mode balun transformers, while the DC RX input is insulated with a broadband transformer. An audio switch box complements the setup, enabling users to listen to either the main transceiver, the SDR output, or both simultaneously. This configuration ensures noise immunity and safety, with the splitter housed in a screened box made from PCB material. On-air tests, such as the CQ WW 160m CW DX Contest, demonstrate the system's effectiveness, showcasing the SDR's ability to handle crowded band conditions with superior selectivity and dynamic range. The SDR's narrow bandwidth filters and waterfall display provide significant advantages, allowing operators to detect weak signals amidst strong interference. The integration of SDR with conventional radios offers enhanced operational flexibility and performance in challenging environments.

The K5USS 6 Meter Hentenna Project page on Hamuniverse provides detailed instructions on how to build a 6 meter directional antenna with 3.5 dBd gain. The project is presented with permission from K5USS, Charlie of Richardson, Texas. This directional antenna is a full wave loop on 6 meters, horizontally polarized but mounted vertically, with a 50 ohm impedance, ideal for 6 meter SSB operations. The page is useful for hams looking to construct their own directional antenna for improved performance on the 6 meter band.

This project involved designing a 7-pole Chebychev broadcast band filter to address severe interference issues caused by a new horizontal loop antenna on the KN-Q7A transceiver. The interference overwhelmed the transceiver’s front end, so a custom filter with a 3.5 MHz cutoff was built using silver mica capacitors and type 6 T130 toroidal cores. Encased in a diecast box with SO239 sockets, the filter blocks strong signals from the broadcast band, achieving over 100 dB attenuation. Tested up to 100W, it reduces interference effectively while maintaining low insertion loss across HF bands.

The ICOM IC-705, a popular QRP transceiver for portable operations, often presents unique challenges for field deployment. This resource details practical solutions for common portable setup issues, particularly for _Parks on the Air_ (POTA) activations. It describes a custom bracket for connecting antennas to the IC-705 through a backpack's antenna flap, utilizing a BNC female-to-female chassis mount connector to mitigate cable tangles. The author shares experiences with a DIY magnetic loop antenna, noting its ease of tuning with the IC-705 and successful CW contacts on 40 and 20 meters over distances exceeding **1000 miles**. Another modification presented is a strain relief solution for the microphone cord, replacing the standard spring clip with an easier-to-attach method. The page also mentions using a _Wolf River Parks antenna_ for POTA activations and references the QRPGuys DS-1 antenna as another portable option. Firmware updates and integration with an LDG Z11-Pro II auto-tuner are also discussed.

145 MHz is the target frequency for this 2-meter Skeleton Slot Yagi Stack antenna project. The design focuses on feeding two stacked Yagi antennas using a skeleton slot radiator, which is a unique approach for VHF enthusiasts. The project details the construction process, including the loop tapered matching section for impedance matching, ensuring optimal performance. The use of specific components like the EH789 element holder and MB456 main mast bracket is highlighted, providing clarity on the assembly process. The construction utilizes 20x20 box aluminum bar for durability and precision. Key dimensions, such as the element length (ER-ED4) and main boom spacing (MM123), are meticulously outlined. This attention to detail aids in replicating the antenna design accurately. The downloadable PDF offers comprehensive instructions, making it accessible for amateur radio operators interested in VHF antenna construction. This project is particularly beneficial for those looking to optimize their 2-meter band operations. The inclusion of a skeleton slot radiator and loop tapered matching section demonstrates advanced techniques in antenna design, catering to both intermediate and advanced builders.

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.

Designing a collapsible 6-meter beam antenna involves careful consideration of element geometry and feedline matching, as demonstrated by VE3SMA's project. The construction draws inspiration from foldable dipole concepts and established wire beam designs like the Penn. State 40m beam and the DJ4SA Spiderbeam. Utilizing **4NEC2 modeling**, the author optimized element lengths for gain and bandwidth, observing the impact of end loops on resonant frequency and the need for compensation. Feeding the approximately 25-ohm balanced antenna with 50-ohm unbalanced cable required a specialized network. This setup incorporates a choke **balun** and a matching section built from two series quarter-wave transformers using readily available 75-ohm cable. On-the-air results validate the design, including a successful 1st double hop Es QSO with 10 Watts and satisfactory performance in the CW WW VHF Contest from FN05, where 41 grids were worked with 100 Watts, showing improved performance over a simple dipole.

This article explores the powerful features of AutoEZ as an Excel application working with EZNEC antenna modeling software. The article demonstrates how variables, equations, and formulas enable versatile antenna design and automatic optimization. Through practical examples including dipoles, inverted vees, delta loops, and monopoles, the author shows techniques for achieving resonance, implementing transmission line resonators for broadbanding, and optimizing antennas across frequency ranges. The step-by-step demonstrations cover unit conversion, coordinate calculations, segmentation considerations, and SWR optimization. This practical guide illustrates how AutoEZ extends EZNEC's capabilities, making complex antenna modeling more efficient and accessible.

This resource presents the design and characteristics of the K9AY Terminated Loop, a compact directional receiving antenna system. The document details the antenna's physical and electrical configuration, consisting of a wire loop, a 9:1 impedance-matching transformer, and a terminating resistor. It describes how the antenna achieves directionality, favoring signals from the feed point end and rejecting signals from the terminating resistor end by several S units. The system is designed for low-band operation, specifically mentioning its application for improving reception on bands where space is a constraint. A four-direction system, utilizing two loops oriented at right angles with a relay-controlled switching system, is discussed. The resource includes a comparison of the K9AY loop's footprint to that of an equivalent EWE array, indicating the K9AY system requires approximately 1/7 the area while maintaining similar directional patterns. The design prioritizes signal collection sufficient for use with modest preamps, such as those integrated into HF transceivers. The article was originally published in QST in 1997.

This is a group to exchange views, help and ideas for improvement of the Automatic Magnetic Loop Controller, as described at VE2AO web site. The Automatic Magnetic Loop Controller tunes a Magnetic Loop Antenna in real time, tracking every movement of the Transceiver VFO, by polling the Transceiver for frequency information and calculating an appropriate Capacitor position accordingly. The Controller can also perform Automatic Tuning based on SWR measurement.

This FAQ covers building and buying transformers for loop-on-ground and Beverage antennas. Building one uses ferrite cores and thin wire. Buying is an option, with the DX Engineering BFS-1 being recommended. These transformers isolate the antenna from the cable to prevent unwanted signal pickup.

The ZL1WTT resource details an experimental software-based Digital Amateur Television (DATV) system, demonstrating the multiplexing of up to six standard-definition (SD) and one high-definition (HD) channel utilizing _h264 compression_. The author encountered peak data rates reaching 32 Mbit/s, necessitating a shift to Freeview and Sky settings (22.5M Sym/s 3/4FEC) to manage bandwidth. The setup employs four networked computers, with a laptop functioning as the multiplexer to re-code PIDs for various inputs, including looped MPEG2 playlists, MPEG2 encoder card input from a VCR, satellite feeds, and an off-air UHF receiver. The system highlights the inherent flexibility of the DVB transport stream, supporting diverse formats such as MPG2, h264, AC3, and AAC. A significant advantage of this software-defined approach is the absence of video quality degradation from stored MPEG2 files to the displayed output, coupled with the ease of reconfiguring settings for MPEG2 encoder cards (e.g., size, bit-rate, frame rate, video input, coding format) and satellite receiver cards (e.g., frequency, LNB volts, symbol rate, FEC). The author also discusses the development of a new graphical user interface (GUI) using _Gambas_ for Linux, aiming to simplify configuration for this DATV project. Specific hardware components mentioned include Hauppauge WinTV PVR-150 and Nova-S plus cards, with a focus on optimizing analog video input via Y/C (S-video) to minimize frequency roll-off. The resource also provides insights into data rates for HD (1080i) content, recommending 8 to 12 Mb/s for optimal performance. Software utilized includes _Ubuntu Studio 10.04_, WinFF, VLC, and TMPGEnc Editor, underscoring the project's reliance on open-source tools and a foundational understanding of LAN networks and DVB transport streams.

Constructing a 4:1 Guanella current balun involves cross-connecting two 1:1 current baluns. At the low-impedance end, transmission lines from each balun are connected in parallel, while at the high-impedance end, they are connected in series. This configuration allows the device to achieve a 1:4 impedance ratio, effectively transforming a 200-ohm load to 50 ohms. The balun described utilizes **FT240-43 toroids** wound with 2.5mm2 twisted pair cable for 8 turns, intended for use with a 20m **Deltaloop antenna**. Measurements performed with a 200-ohm resistor demonstrate satisfactory VSWR and impedance characteristics across the HF bands. The article compares the performance of 2.5mm2 cable versus 1mm enameled wire, recommending the former for superior efficiency. Emphasis is placed on maintaining short core-terminal connections to optimize performance. Additional considerations include the option of integrating a separate Common Mode Choke (CMC) for enhanced common mode current suppression, especially if the balun's inherent suppression is not prioritized.