• News

• Result

• HamRadio

• DXpedition

• Field day

• QSL info and gallery

• Sail and Sea

• Technique & Projects

• Link

• to Main page

RA3WDK `s Homepage

Feed Horn

Ham`s who work on SHF band from field condition or with small setup know many reason to have a multiband antenna system. Dish is very effective antennas for 23 cm band and above. Many Ham`s use one dish for some bands by change feed horn or antenna module. For example i also use two changing modules of 6 and 3 cm band for small offset TV SAT dish .

DL4EMA Guenter[1] made loop feed of 23 cm band for prime focuse dish and RA3AQ Dmitrij [2] made some different design of loop and diameter of reflector.

1. Parabolic Dish Ring Feed (1998) DL4MEA http://www.qsl.net/dl4mea/ringfeed.htm
2. Ring Feed for Field day (2008) RA3AQ http://forum.vhfdx.ru/paraboly/prostoi-obluchatel-dlya-paraboly-na-polevoi-den/

The main advantage of a loop feed is very simple mechanical configuration and good performance of antenna system for Field days and QSO by TROPO propogation.
I made dual band feed horn with loop feed of 23 cm and additional horn of 6 cm band. This configuration is also simple and has necessary radiation pattern for illumination dish with 0,3-0,42 F/D. The dual feed horn has separate input for both band. The small horn of 6 cm is located inside and behind reflector of loop feed. Part of feed horn of 6 cm using axial choke at the open end of the waveguide and has not influence for part of 23 cm.
The radiation pattern in Figure below shows that the main lobe for 23 cm band has beam width about 130 degress and for 6 cm - about 110 degress. The radiation aperture such as the open end of a rectangular waveguide and loop has near of equal beam width pattern in E and H plane . The backward radiation of this feeds has good suppress and level sidelobe is low .

Dual band FeedHorn for 1296 and 5760 MHz Pattern for 5760 MHz Feedhorn for 1296 MHz has been made by RA3AQ and later I added feedhorn for 5760 MHz . Pattern for 1296 MHz Measured radiation pattern Victor UA9YLU made this Dual Band Horn for his Dish SVEC 1,8 m . He got ratio Noise from Sun / Cold Sky - 7 db for 1296 MHz and 4,5 db for 5760 MHz Vladimir R3GC made this Dual Band Horn. He used saucepan for reflector of element 1296 MHz. Alexander UA3OW made this Dual Band Horn. Alexander RA9QAW made this Dual Band Horn     Horn for 10 GHz with angle of 110 degrees for illuminating Dish F/D 0,35-0,5 Description of S11 for horn with angle of 110 degrees:   Feed horn 10368 MHz , SWR <1.1 Click for large image : Other Horn for best illuminate offset dish (80 degr) , aperture size 45x30mm , waveguide size 23x10mm   Horn 5760 Mhz for offset dish (80-85 degr.) , click for full size image     Dual Mode Horn 5,7 GHz optimise for 75 degr. offset TVS Dish and Horn for 80 degr offset TVS Dish click for full size image Measured radiation pattern Horn for 80degr offset TVS Dish   Dual Mode Horn 24 GHz optimise for 85 degr. offset TVS Dish   click for full size image SWR < 1,5 23-26 GHz       Compromise Short Horn 5760 MHz for 85 degr. offset TVS Dish SWR < 1,2 5760 MHz Measured radiation pattern of Compromise Short Horn for offset TVS Dish Modification horn for TV SAT dish in 10368 MHz band Increase in internal diameter to 20 mm !!!   Horn for F/D 0,6-0,7 Modification Horn from SAT LNB - increase diameter to 18,5 ìì inside     "Cold" horn for measurement Noise factor of LNA on 5,7 Ghz and 10 Ghz   Multi Mode Horn with Bi- Orthogonal polarization for Offset dish, 5,1-5,6 GHz for Wi-Fi.