Calculated resonance 21.995 MHz but in practice it’s around 21.600 MHz

This article describes a specific procedure to adjust a shunt matching coil to assure that the input SWR will remain relatively low

This article explores a theoretical model for the losses of an 80m / 40m trapped inverted V dipole antenna system using a bootstrap coax trap

The calculation refers to either a loaded 1/4 wave or a loaded dipole

Building coils for a portable dipole using

In search of a software for the hatches: coaxial-traps. why also coaxial hatches? i chose this system, because not having 1.5 mm² copper wires to use, i had however a lot of cable 75 ohm coaxial for cctv

I sprayed the antenna down with water to check for detuning, and lost 4dB of signal in my field strength tests

Wire coils are used in a number of amateur radio projects especially antenna projects

calculator for creating a loaded, shortened quarter wave vertical or balanced dipole

Experiments and measurements been made on loading coils using net standing wave current

A loading coil for the AD5X portable vertical antennas

Nei dati immessi usare il punto (.) come separatore e non la virgola

Calcolatore per le bobine,Calcolo Lunghezza D’onda,Calcolo Risonanza

Trap-style Inverted-V Antenna for 3.5, 7, 14, 21 & 28 MHz i.e. 10 to 80 metres

Wire traps do exhibit a high Q-factor so are in theory less lossy compared to coax traps, but are NOT SUITED for high power 200w

Loading coil is one of the most discussed parts of the lf equipment, my loading coil is split into two parts

Let's work through the design of a simple-to-construct low-cost antenna trap

For the trap to be effective, its impedance must be much greater than that of the antenna power point,close to 50 ohms

10 meters of vertical that makes for a handy 1/4 wave for 40m, 30m, 20m, 17m

Mean diameter of the air core coil, measured from conductor centre to conductor centre include the wire insulation thickness, if any

The Unadilla trap is constructed with two concentric lengths of aluminum tubing separated by an insulating layer, thereby forming the parallel capacitor

Traps are useful for multiband operating of all kinds of antennas

Coax traps are cheap, easy to assemble in a reproducible manner, very rugged, perfect for portable or permanent operation, on dipoles, inverted-V's etc

è da parecchio tempo che sono alla ricerca di un sistema per misurare le trappole senza piena soddisfazione

A multiple band dipole can be made very easy to build

I have been using a 40m End-Fed Half Wave EFHW antenna very successfully for the last few months and I wanted to extend the design to multi-band whilst avoiding the need to take a tuner along

Using a dos program from Brian Beezley K6STI, it was possible to design some low loss loading coils

KF7GT the making of a dipole trap antenna

La funzione della trappola, è di isolare tratti di filo per consentire il funzionamento dell'antenna su diverse frequenze

There are several ways to reduce the length of a dipole and still use it as an effective antenna

The idea of parallel circuits or traps in a dipole antenna to obtain more than one resonance was first conceived by G8KW

Trap on Coaxial Cable Igor Grigorov, RK3ZK a multi-band antenna or a symmetrical antenna is installed

Trap dipole 7-10-14-18-50mhz with balun coax cable

Looking at the sketch above, when working 40 m only the red wires are part of the antenna but when using 80 m the red and purple wires are the antenna

Sono stati realizzati due circuiti risonanti di facile riproducibilità e meccanicamente di adeguata robustezza

Before you start, bee sure that you know exactly where you would hang the dipol

My trap dipole exists in the form it does because, like many of us, the garden is too small

It contains measurements of traps, performance of trap antennas using models of traps, and ideas on how to make trap antennas more efficient

This trap which is nothing more than a tank circuit capacitor and inductor in parallel made out of coaxial cable and pvc

Ho realizzato un programma chiamato Trap che, con metodo iterativo ma molto rapidamente, sintetizza il filtro, ne calcola il numero di spire e verifica la frequenza di risonanza

The problem with making your own trapped HF antennas is usually getting the coaxial traps tuned to frequency

The traps were tested using a coupling loop to the homebrew antenna sweeper and with a little squeezing, they tuned to 21.1 MHz

I have been looking at the typical roller inductor used in antenna tuners and some amplifiers and I have come up with what I think is a better design

Antenna verticale 30M 10MHz home made

Wire traps are cheap, easy to assemble in a reproducible manner, but can be mechanically fragile easily deformed , good for permanent operation, on dipoles, inverted-V's etc

Using 3/32" 0.09375" or 2.381 mm Harris 4043 aluminum wire to make the coil