AboutChris Bushman Expertise I have been an amateur radio operator for about 36 years.
Experience In real life I manage a small motion picture film lab in Hollywood. I've been a fireman, a teacher of English in Okinawa, a personal computer tutor.
I am an Advanced Class Ham radio operator using my originally issued callsign WB6EEQ. I have operated for extended periods of time from Okinawa (KR6FX & KR6OP), Texas (K5VXG), and Mississippi (K5TYP).
While in the Air Force, I was a Manual Morse Radio Intercept Operator.
BS Zoology, UC Davis
Member, Society of Motion Picture/Television Engineers http://www.smpte.org/ - Member, American Radio Relay League http://www.arrl.org/ - Member, Quarter Century Wireless Assn. http://www.lockport-ny.com/radio.htm - President, Zen Nippon Airinkai, So Cal Chapter http://ourworld.compuserve.com/homepages/Chris_Bushman/ - Member, Maltose Falcons Homebrewing Society http://www.westval.com/mfalcons/ - Alumni, American Brewers' Guild http://www.abgbrew.com/
Question First, let me say thank you for being available to answer the sometimes inane questions of novices such as myself.
So here goes, I have a shortwave radio (Grundig YB-400PE), an old Midland CB radio (40 channel) and I hopefully will be getting a radio scanner soon.
What I would like to do is to install all 3 pieces of equipment in my shed and use them individually when time permits. Can I install one antenna which could service them all effectively. This would of course require a splitter of some sort so I wouldn't needed to be constantly pluging the antenna in/out of each unit. I would only be using them one at a time.
Any suggestions on an antenna that could do this? I was planning on getting mobile whip antenna and installing it on a 10 foot pipe in my backyard. I know that sounds kind of hokey but I would like to do this as cost effective as possible but still be effective.
Thanks again for you time in answering my questions.
Jim Kempf
Answer Jim, I admire your innovative and creative spirit. No question is unworthy for people like you.
Here's the general rule of antennas. The optimum size of an antenna is determined by the frequency (which corresponds to the wavelength). Higher frequencies have shorter wavelengths and lower frequencies have longer wavelengths. An antenna will work best for only one frequency.
The three radio systems you mention cover three very different frequency ranges. Shortwave receivers are MF and HF (Medium Frequencies and High Frequencies) in the range of 300Khz to 30Mhz. CB radio is at the top end of that range at 29Mhz. Scanners usually cover the VHF & UHF (Very High Frequency and Ultra High Frequency) bands which range from 30Mhz to 3Ghz.
One type of antenna called a quarter wave vertical would be around 40 feet tall for a freq of 7Mhz, around 9 feet tall for 29Mhz, and 19" for 144Mhz. Up around 3Ghz we're talking parabolic dish antennas like for satellite TV.
But the good news for you, since you are (mostly) not transmitting, antenna size is not super-critical. If you were to transmit using a grossly mismatched antenna, it could blow up you transmitter.
So what you really need to do is get some metal up there that can best suit your needs. Since you might be transmitting on CB, do exactly what you suggested and throw up a simple mobile CB whip antenna (without coils). It will work well on 29Mhz and good enough on the other freqs.
Get yourself a coaxial antenna switch so that you can use the one antenna for all 3 radios. Something like...
