charlienorth

I bet your Tonna antennas would be good for direction finding! I guess you'd need a tank and 40 acres to turn the things though. :) If I am understanding what you mean, the 1/4 wave bazooka or the 1/4 stub would seem to cost the same (almost nothing) since the pieces needed are virtually identical. By 1/4 wave stub, you are meaning the design that has the same tube as the bazooka but is oriented to the side of the feed and attached to both the shielded ground and the center feed at the antenna?

Thanks again for your response. In recommending the bazooka, do you feel that it is superior to the cheap Radio Shack type 75 to 300 ohm units?

I am back to realizing the impedances need to be matched. -------------------------------------------------------------------------------- >Scott Fintel said: >Most all of your TV antennas use them to go from 300 ohm leads >on the antenna to 75 ohm cable. And tekwiz at the Electronic's Forum just told me that is exactly what is needed th balance the transceiver/antenna impedances on the FRS RDF setup. http://www.dutchforce.com/~eforum/index.php BTW, Joe Leggio was kind enough to reply to my query about designing the Yagi for FRS radios with the advice to scale all dimensions down, including the element (tape) diameter, with the following ratio: Scaling factor = 145.565/465 Scaling factor = 0.313

And here I thought you'd make it! http://www.aaroncake.net/circuits/6-12conv.htm

Oops, I care about receiving not transmitting right? (And the balun reguards matching antenna/transmitter impedances?) "Coupling" the receiver to the antenna is my concern correct?

I looked up baluns in the 1993 ARRL Handbook. The bazooka balun (Figure 14B, page 16-7) looks like it will balance the impedances if the bazooka sleeve is 1/2 the length of the driven element. Have I got that right?

Thanks again for your reply. You are not putting me off at all. I need to learn at least a little of this and thanks to you I learned a couple new terms. Yagi Cad says this design that seems good and that ithas input impedance 11.6 +j 0.0 Ohms I can research how to make a balun but I'm not sure what it is that I am to match? You promised the program would tell me. :) Here's what I input and the results from YagiCad in meters/mm: 465.14 3 20.32 20.32 20.32 20.32 20.32 .3462315 .3064886 .289976 .2571061 .244101 5.631533E-02 7.568619E-02 .1289118 9.078011E-02

Thank you very much. I'm glad you've used the program successfully. It sure looks like a novice like me possibly could make it work. I'll use the YagiCad program to design for 465.13 Mhz. I understand that I am looking for a foward looking pattern as shown here: http://home.att.net/~jleggio/projects/rdf/tape_bm.htm It also seems a low impedance is important but I also read that it is very important to match the feed impedance to the antenna impedance. Sorry to say, I have no clue how to do that. I do have experience destroying things by not matching impedance. (Hooked a sound card to a new boombox, argh

Hi All I am afraid that I know nothing about RF. May I appeal to you for help with this project? I bought 4 FRS radios and am about to equip a few rockets with them in a manner similar to this: http://www.nakka-rocketry.net/frs.html#top The radios that I have are capable of continuous transmission so the 555 circuit will be replaced with a buzzer mounted near the microphone. I plan to make a RDF Yagi like this: http://home.att.net/~jleggio/projects/rdf/tape_bm.htm I plan to use YagiCad 4.1 to design the antenna. http://www.ipass.net/teara/kq3.html My (first) question for you is may I design for the middle of the FRS frequencies, say 465 Mhz, in an attempt to be able to use them all or must I design it for one specific frequency? FRS Channel No. (MHz) 1................... 462.5625 2................... 462.5875 3................... 462.6125 4................... 462.6375 5................... 462.6625 6................... 462.6875 7................... 462.7125 8................... 467.5625 9................... 467.5875 10.................. 467.6125 11.................. 467.6375 12.................. 467.6625 13.................. 467.6875 14.................. 467.7125