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Ever need a way to estimate the amount of wire to add to or remove from a center-fed wire dipole antenna to achieve resonance at a desired frequency? This article help to determine correct wire lenght.

Constructing a compact, single-feed triband Moxon antenna for 20, 15, and 10 meters is detailed by DU1RZ, drawing from his personal experience with space-constrained antenna projects. Initially fascinated by cubical quads, the author transitioned to Moxon designs in 2005 after realizing his roof space was insufficient for a bulky quad. His first experimental monoband Moxon for 15 meters, built from repurposed materials, provided solid DX QSOs for seven years, despite being slightly below the 21 MHz band center. The project outlines the design process, including using the _MOXGEN Calculator_ for element dimensions and material selection, such as #14 AWG enamel copper wire and fishing poles for spreaders. DU1RZ shares insights from simulations with DL2GMS regarding insulated versus non-insulated wire performance, noting that insulated wire can shift resonant frequencies lower. The assembly instructions cover preparing wire elements, connecting feed points, and tuning the antenna, with initial SWR measurements taken at 10 feet and final readings on a mast showing excellent results: 1.0:1 on 14.225 MHz, 1.1:1 on 21.250 MHz, and 1.3:1 on 28.50 MHz. Transmission tests with 4F1BYN indicated a front-to-back ratio of approximately 2 S units with 10 watts output. The author emphasizes adaptability, encouraging builders to use readily available materials rather than strictly replicating his setup. Key observations from DU1RZ and DL2GMS highlight the antenna's strong performance across 20, 15, and 10 meters, good front-to-back ratio, full bandwidth on 20 and 15 meters, and its small turning radius of about 4.18 meters (13.54 feet), making it suitable for limited antenna space. Its lightweight construction and low wind load are also noted as significant advantages.

Use this online calculator to determine the length of a quarter-wave antenna from the frequency. Both metric and English units of measurement are supported.

Use this online calculator to determine the length of a full-wave loop antenna from the frequency. Both metric and English units of measurement are supported. Quarter-wave matching section lengths are also calculated.

Use this online calculator to determine the length of a dipole antenna from the frequency. Both metric and English units of measurement are supported.

ICNIRP is a calculator software that allows you to determ safety distances for many know amateur radio antennas with respect to ICNIRP limits developed by DL9KCE

Free basic and advanced system design tutorials for every component and aspect of solar power. Plus system sizing calculators, battery bank calculators and wire size calculators

Online calculator and a full documented pictorial guide to build a single sided 8 slot waveguide antenna

This article includes an online calculator for a 3 element Yagi Antenna. The formula and basics theory of Yagi Antenna are also explained with examples.

Types of coax-cable with rf attenuator calculator, line loss calculator form includes an antenna gain calculator. This coax loss calculator can help you on choosing the right cable for your antenna sysmte.

Online calculator, Butterworth Bandstop (Notch) Filter Designer

The HA8TKS VHF DXCluster is an essential online resource for amateur radio operators focusing on VHF and higher frequencies. This platform provides real-time information on DX spots, allowing users to track and engage in two-way radio communications effectively. The integrated map mash-up feature enhances the user experience by visually displaying the locations of DX stations, making it easier for operators to plan their contacts and optimize their antenna setups based on geographical data. In addition to the DXCluster functionality, the site offers various HAM tools, including a QRB calculator, which helps operators determine the distance to DX stations based on Maidenhead grid locators. The platform supports multiple modes of operation, including CW, SSB, RTTY, and digital modes like FT8 and JT65. With a user-friendly interface and comprehensive data, the HA8TKS VHF DXCluster is a valuable asset for both novice and experienced operators looking to enhance their DXing and contesting activities.

Calculate the value of an unknown resistor with this free program for windows

An excel spreadsheet that in a really simple way checks how much to trim your antenna elements. Download the xls file and watch the presentation video include in this page

The Triple-M-beam calculation program is used for the calculation of Triple-M-beam antennas by DG0KW

A collection of calculators, contest schedules, references, databases and more for Palm OS by KB7AVT

Online calculator, to convert dbWatts to Watts and vice-versa, or ERP and EIRP by G4URH

Design a parallel circular wire balanced transmission line with this online calculator. This calculator is a tool for designing balanced transmission lines with a specific desired characteristic impedance Zc and made of parallel circular conductors of a given diameter d.

Use this online calculator if you need to know your azimuth/elevation relative to a satellite

HF Beam Calculator for Amateur Radio and CB Communications

This calculator is designed to give the critical information of a particular beam antenna, in this case a three element Yagi, for the frequency chosen.

The collinear antenna, or Marconi-Franklin antenna, is an omnidirectional, high-gain antenna composed of in-phase half-wave dipoles aligned vertically. By using quarter-wave transmission line segments, it maximizes gain at a low horizon angle, outperforming a half-wave dipole. Adding segments increases gain but narrows bandwidth. A popular DIY version, the CoCo antenna, uses half-wave coaxial cable segments connected by non-radiating transmission lines. Built with stable velocity factor cables, a matching quarter-wave sleeve balun, and ferrite rings for attenuation, the antenna achieves performance comparable to commercial models.

Calculate vertical array pahse antenna accorting to the Christman technique

The dbm online calculator and reference table for 50 Ohm

Passive Band-Pass Filter, low-pass filter calculator

Aka Circular Waveguide Antenna. This online antenna calculator let you plan your cantenna for the desired frequency of operation, giving the Can diameter you have available.

This calculator estimates the efficiency of a T match tuner using a simple loss model.

Calculate how to set call signs

1.5 dB of matched line loss can be calculated for a given transmission line using this online tool, which employs a model calibrated from empirical data. The calculator allows radio amateurs to input specific transmission line types, such as _RG-8_ or _RG-58_, and then determine the expected signal attenuation. This is crucial for optimizing antenna system efficiency and understanding power delivery to the radiating element, especially for HF and VHF operations where feedline losses can significantly impact performance. Beyond matched loss, the calculator also provides an estimate for mismatched loss if the Standing Wave Ratio (SWR) is specified. This feature helps operators quantify the additional power loss due to impedance discontinuities between the transceiver, feedline, and antenna, which is a common concern in amateur radio installations. Accurate loss calculations are vital for effective station design and for predicting actual radiated power. The tool's utility extends to various operating scenarios, from fixed station setups to portable deployments, aiding in the selection of appropriate feedline lengths and types to minimize signal degradation. Understanding these losses is a fundamental aspect of maximizing the effectiveness of any amateur radio antenna system.

The program can be used to calculate inductors (coils) and their number of turns on ferrite cores, ferrite shells and air coils. These can be used for baluns, Ununs, bandpass filters, low pass filters, resonant circuits, and more. The technical specifications of the cores are already integrated in the program. Application is free and runs on Windows 32 bit versions only. To make it run on Windows 10 64 bit need to be unzipped in a single folder.

Online coax cable impedance calculator

Online VSWR Voltage Standing Wave Ratio Calculator

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.

This is an on-line rf attenuator calculator provided free in order to promote the FLEXI-BOX. Calculates the resistor values, attenuation, minimum attenuation, impedance, reflection coefficient, VSWR and return loss of a matching Pi attenuator

Inches and meters Javascript Wavelength Calculator allow to input a frequency in MHz and calculate wavelenght in several units considering also fractions of wavelenght and the velocity factor. Includes an usefull inch to meter converter

Online calculator for Input coil data, LC Resonant Frequency and L match

The program consists of tabbed pages for various antenna and transmission line calculation. You can compute the values for an inverted L network that will allow you to match the 50 ohm output of the radio, or you can compute the necessary length in the units of choice for a 5/8 wave vertical for 10 meter band.

Online calculator for J-Pole antennas. The J-pole antenna consists of a short and a long vertical pole with a feed point near the bottom. The antenna looks like the letter J, hence the name J-pole antenna.

Electrical and electronics online calculators by Calculatoredge.com

The calculator designs the Yagi-Uda antenna based on the DL6WU model with boom correction, following the G3SEK-DL6WU method. It optimizes the antenna for maximum gain and allows adjustment of passive elements without affecting SWR. DL6WU antennas are known for their high gain, minimal sensitivity to nearby objects, and stable performance in various weather conditions.

Online Constant - k Lowpass Filter calculator

Select the toroid by material type and dimension of the toroid, the desired inductance and you will get the numbers of turns

Butterworth Highpass Filter Designer

Basic priciples of Yagi antennas and its variations like Quagi antennas, Quad antennas includes pictures, drawings and online calculators by KN9B

Mic online calculator , Microphone Dynamic Range Calculator, Microphone Sensitivity Calculator

This online calculator will give as output the Inductance L of a coil, including the total lenght of the wire needed to wound the coil. As input, requires the Diameter, number of turns, wire diameter and turn spacing

This calculator ask as input diameter, lenght turn and frequencu and will return L and Q

An online multiple calculator of 16 impedance matching networks

Online HB9CV antenna calculator, accept as input the desired resonating frequency and provides dimensions for spacing and length of each element, including boom and radiator diameter.

A free Labview antenna calculator program. This interesting calculator for small loop antennas can be ran on most recent Windows versions using the Labview runtime.