1. The most important aspect of any low frequency antenna is the antenna impedance, Car radios have an antenna impedance of 75 to 100 Ohms which make it easy to use external antennas, Desktop radios and Hi Fi sound systems (Panasonic, Kenwood, etc) have a 300 Ohm or higher AM antenna input impedance or they may use an internal ferrite core antenna and have no simple way of including an external antenna.
Note: Kenwood and Panasonic desktop brand Hi Fi systems or radios are notorious for having high impedance antennas which make it impossible to have external antennas, these type of radios usually come with a twisted wire external antenna in the shape of a small square using plastic covered twisted wire. You+ cannot easily improve the reception without the use of a balun.
2. The next most important aspect is the antenna feed line or cable cable capacitance, It is important that when including an external antenna you use Low Capacitance coax such as RG62b/u, Do NOT use CB coax RG58 as this will attenuate the AM signal, It will not however, attenuate your FM signal.
1. If you are using cable to go from your antenna to your transceiver in you car then you should be using 50Ohm coax only, coax such as RG58 or RG58C/U is excellent, you can also use a lower loss cable such as RG8 or RG213 but there will be no advantage in doing so, Coax shuch as cellfoam or celfoil coax should not be used unless you have major electrical noise as thas coax has too high capacitance for 27MHz.
2. If you are using lengths longer than 4mtrs try to stay with multiples of 1/2 wavelenghts eg 12 feet 24 feet 36 feet etc
3. Never coil excess coa, always keep you coax cable as short as practicle and with no patching lenghs with connector, if you need to attach two lengths of cable I always suggest using BNC or TNC connectors.
1. The best cable to use is Low Loss Good Quality RG58C/U coax for lengths shorter than 5mtrs, anything longer I suggest using RG213 however you can use cellfoil or cellfoam coax as well as these are mainly used in higher frequency applications they do have equal low loss specs as RG213.
2. No need to run cables at particular lengths just as short as possible as the longer the coax the greater the loss
Special Cables from Mobile One
Any type of cable length and connector combination can be made to customer order with the following options:
RG58, RG58c/u, RG58 Mil-17-C, RG58 Cellfoil, RG59c/u, RG62b/u, RG174
PL259, SO239, BNC, TNC, N Type, FME, F Connectors, SMA, SMB, MMXC, RCA, PN57, B&L (TV)
A wide variety of gender-bender adapters are available to cross connect
PL259, SO239, BNC, TNC, N Type, FME, F Connectors, SMA, SMB, MMXC, RCA
GENDER TO GENDER
We stock a range of double male and double female as well as right angle adapters to suit PL259, SO239,BNC, TNC, N Type.