Remember Me?
Menu
Home
Search
Today's Posts
Home
Search
Today's Posts
RadioBanter
»
rec.radio.amateur
»
Antenna
>
Piano Wire Antenna for Experimental Rocket
LinkBack
Thread Tools
Search this Thread
Display Modes
Prev
Next
#
17
May 24th 09, 09:26 AM posted to rec.radio.amateur.antenna
Owen Duffy
external usenet poster
First recorded activity by RadioBanter: Dec 2006
Posts: 1,169
Piano Wire Antenna for Experimental Rocket
mr1956 wrote in news:943a9bbd-214b-43b2-ac31-
:
I am looking for some help developing a properly tuned piano wire
antenna for an all metal experimental rocket.
This particular vehicle currently uses a Digi International 9Xtream
100 mw transmitter which operates using Frequency Hopping Spread
Spectrum from 910 to 918 MHz.
The first flight used a .062" diameter length of piano wire cut so
that the exposed length was about 1/2 wavelength. The wire antenna was
isolated from the metal airfame with a small nylon penetrator and
connected to the transmitter via about a 12" length of RG-178 coax.
The coax was terminated at the antenna via two small jumpers (soldered
to the center conductor and shield). The shield was grounded on the
metal airframe transforming the entire rocket into an artificial
ground plane (the antenna was also swept back at about a 45 degree
angle to reduce drag.
So you designed for a half wave antenna fed with 12" of RG178.
Lets suppose for a moment that the antenna has a feedpoint Z of say, 2000
+j0 ohms. The line will transform that to 5+j14 at the tx end, and with a
loss of 4.8dB (ie 33% efficiency). The tx is unlikely to develop is rated
output power into such a load, so there will be some further reduction.
Yes, an antenna of half the size (ie a quarter wave fed against the metal
rocket body) might well work ten times as good.
Owen
Reply With Quote
Thread Tools
Search this Thread
Show Printable Version
Search this Thread
:
Advanced Search
Display Modes
Switch to Linear Mode
Switch to Hybrid Mode
Threaded Mode
Posting Rules
Smilies
are
On
[IMG]
code is
On
HTML code is
Off
Trackbacks
are
On
Pingbacks
are
On
Refbacks
are
On
Similar Threads
Thread
Thread Starter
Forum
Replies
Last Post
Transformer Wire = Magnet Wire as a a Light-Weight Antenna Wire {Hidden] Stealth Antenna
RHF
Shortwave
1
June 1st 06
09:47 AM
Single Wire Antenna {Longwire / Random Wire Antenna} - What To Use : Antenna Tuner? and/or Pre-Selector?
RHF
Shortwave
20
December 31st 05
09:41 PM
Single Wire Antenna {Longwire / Random Wire Antenna} - What To Use : Antenna Tuner? and/or Pre-Selector?
David
Shortwave
0
December 28th 05
05:24 AM
Single Wire Antenna {Longwire / Random Wire Antenna} - What To Use : Antenna Tuner? and/or Pre-Selector?
David
Shortwave
3
December 27th 05
09:59 PM
Single Wire Antenna {Longwire / Random Wire Antenna} - What To Use : Antenna Tuner? and/or Pre-Selector?
David
Shortwave
0
December 27th 05
09:18 PM
All times are GMT +1. The time now is
01:56 PM
.
Powered by vBulletin® Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 RadioBanter.
The comments are property of their posters.
Contact Us
RadioBanter forum home
Privacy Statement
Copyright © 2017
LinkBack
LinkBack URL
About LinkBacks