ARI Sanremo Home Page Home Page Nominativo di Sezione ARI Sanremo
Home Main Menu Sezione ARI-RE Award Liguria EME Diploma Sanremo Search Members Downloads Forums Guestbook Login

Toggle Content Trova nel sito


Toggle Content .:Translate Language
Please select to change language

Klicken Sie auf Sprache ändern

Sélectionner pour changer la langue

Haga clic para cambiar el idioma
Autori › Simple, essential antennas for VHF and UHF
Simple, essential antennas for VHF and UHF

Simple, essential antennas for VHF and UHF


The first, known as HB9CV, with few modifications, is really compact. You can homebuild it with few parts: four transistor radio antennas, a Bnc, two pieces of aluminium, two insulators and you will have an antenna that fits into your pocket.
Two elements beam, variable polarization, and about 4,5 db gain. With a small telescoping plastic pole it will be a very lightweight ensemble. With the dimensions established, it is better to hard solder the elements so that they maintain their dimension when opening the antenna, and ensure a good electrical contact. Even if the impedance is 75 Ohms, it will not harm the transceiver.

About the collinear, the drawing is self-explanatory. I used the magnet from a discarded loudspeaker not only for an economc reason, but also with the purpose of screwcutting a radial system (a minimum of three, at 120 degrees) in it. They will be useful if the antenna will be used in places other than the car roof. The lenght of the radials is one quarter wavelenght plus 5% Do not fold the radials at 90° and inox solder the loop in the straight part of them.
To avoid excessive vibrations use a larger section for the antenna. The central insulator is built with a piece of plastic tubing of appropriate dimension, cut vertically in two, filled with epoxy resin and left set in perfect vertical position.
A car and table collinear, not very compact but with good performance.

The third antenna is a baby collinear that, if patiently built, will marvel you with it’s efficiency. If you want the best use "N" connectors on the base and on the antenna. If you do this and you intend to built also the antenna of fig. Two you can use "N" connectors on the base of that antenna and use that base for two or more antennas.
Use silver plated copper wire 1,2 mm dia. for the coil. The coil form is made of teflon, screwcut so that the coil will not move under vibration; good soldering throughout and no sharp turns. Fix everything with good quality epoxy. The whip is made of inox steel, other parts chromed or silver plated brass. The coil shield is soldered to the PL (or N) connector.
The two central conical insulators bear 3-4 mm grooves to help the epoxy resin to form a solid mechancal ensemble. On the same pieces use set screws for the winding and for the whip. Make long holes for fine adjustment of the system. Use good quality capacitors with 500 Volts insulation.
The performances are as follows:
VHF gain about 2 Db; UHF gain about 4 Db. Very good bandwidth and SWR 1 : 1,2.
To complete your mobile setup, next is a duplexer useful for home work as well. Duplexers are quite expensive and with a little work we can save money. Build it on printed circuit board, use silver plated copper wire, good quality capacitors mounted on the opposite side of the copper. Enclose in a metal case for shielding. Max power is 50-60 Watts and lossses are quite low.

Suggested dimensions by IK1UWL for an optimized HB9CV:


Length Reflector
Lenght Radiator

Free space performances:

Gain
F/B
SWR (144 ÷ 145 MHz)

At 2 metres over ground

Gain at 30° elevation
Gain at 9° elevation
F/B
SWR (144 ÷ 145 MHz)

524 mm
462 mm



3.35 dBi = 1,2 dBd
3,98
1,33



4,44 dBi = 2,29 dBd
3,40 dBi = 1,25 dBd
3,43
1,32


Download drawing: HB9CV and Collinear 

Attilio I1BAY, I QRP #309

Italian version



(3051 letture) Pagina Stampabile

[ Ritorna a I1BAY ]




Nominativo di Sezione
Sezione A.R.I. Sanremo - 18.02 codice ASC che per la Sezione è G08

La Sede si trova in corso Mazzini n° 1, a fianco del Campo Sportivo, in Sanremo. La Sezione è aperta tutti i martedì, non festivi, dalle ore 21 alle ore 23 circa.

Indirizzo Postale:

ASSOCIAZIONE RADIOAMATORI ITALIANI
SEDE di SANREMO
CASELLA POSTALE 114
18038 SANREMO IM


Scrivi al Segretario
ASSOCIAZIONE RADIOAMATORI ITALIANI P.IVA & C.F. 90029580082
Indirizzo di posta elettronica certificata
presidenza@pec.arisanremo.it

Webmaster IZ1OQB PINO

Contatto per il Webmaster
Regolamento del Sito | Note Legali/Disclaimer | Come trovarci


Best viewed 1024x768 +

Questo sito appartiene alla Sezione ARI di Sanremo (IM) e non rappresenta una testata giornalistica in quanto viene aggiornato senza alcuna periodicità.
Non può pertanto considerarsi prodotto editoriale ai sensi della legge n. 62 del 07.03.2001.
I loghi, i marchi e gli script usati in questo sito appartengono ai rispettivi proprietari e a CPG-Nuke Team.
Questo sito utilizza la versione 9.2.1 di Dragonfly CPG-Nuke.
Theme by i1yst
Tutti i testi, le foto e i disegni tecnici sono esclusiva proprietà di © 2002-2013 arisanremo.it
Vietata la riproduzione e la copia, anche parziale, senza la previa autorizzazione di arisanremo.it

All content are protected by the copyright law and may not be copied without the express permission and the active reference to a source!
Web stats

Interactive software released under GNU GPL, Code Credits, Privacy Policy



placeholder Support GoPHP5.org   Dragonfly   XHTML valid!   CSS valid!   Level Double-A Conformance icon, W3C-WAI Web Content Accessibility Guidelines 1.0   RSS valid!   Robots valid!   PHP   PhpMyAdmin   MySql   Get Adobe Reader   Unicode   Add to Google placeholder