help required

[chandramanikumar]

hey people i have to design a highly directive antenna for a direction finding device operating in the 100 to 500 MHz band, can u plz help me out on this.

 

[crayon]

What you need is a yagi. There is a ton of stuff out there via google that can get you started.

 

[Al42]

A Yagi that's directional over a 5:1 frequency range? Yagi's turning over in his grave. To maintain directivity the antenna must maintain spacing and element length - in wavelengths - and that's not possible over that great a range.

chandramanikumar, what does "have to design" mean? A class assignment? A job requirement?

 

[STiMULi]

What does mastiland.com do?

 

[gcgrotz]

try a log periodic type. Buy one from somebody like grove.

 

[prcguy]

Directional antennas in the general sense are not the usual antenna for direction finding. Antennas that null are used for greater precision in determining the direction. A log Periodic can easily be designed to cover the range you desire but even a high gain version will still have a beamwidth that is too wide for determining a precise bearing.
prcguy

 

[traumacop]

What about the Diamond MAY1000?

Also what about the WB2HOL Tape Measure Beam..

Arrow antennas sell different fox hunt antennas.

Used with a micro sniffer, you should develop decent skills.

Good Luck

 

[SCPD]

hey people i have to design a highly directive antenna for a direction finding device operating in the 100 to 500 MHz band, can u plz help me out on this.

Have you considered a switched antenna array? This may have the same wavelenghth geometry issues as other types. RF switch cycles through the antennas to an FM receiver - which compares the phases differences. I think Ramsey even has a kit for this.

I'm also wondering if something like an ADF could be made to work in the range - goniometer plus loop and sense antennas.

-rick

 

[crayon]

A Yagi that's directional over a 5:1 frequency range? Yagi's turning over in his grave. To maintain directivity the antenna must maintain spacing and element length - in wavelengths - and that's not possible over that great a range.

The OP specifically asked for a "highly directive antenna". And since one cannot have directivity *and* bandwidth, correct me if I am wrong, that only leaves yagi's, L/P, dishes, et al types of antennas.

I also assumed he really did not know what he was asking for :wink: , and would narrow/lower his DF expectations after doing some research on google about yagi's.

 

[NAVCAN]

This is a typical DF antenna array use for VHF direction finding in the air-nav field. The spacing between the antenna's are a 1/4 wavelength apart.http://7.photobucket.com/albums/c153/lowa2/DSCF2310.jpg