Wednesday, June 26, 2019

Loop receiving antennas for medium frequencies

Unlike for transmitting, you don't need very big antennas for receiving medium frequency stations. This is because most receivers (apart from crystal sets) are sufficiently sensitive. It's more important to minimise noise and interference from stations on the same or nearby frequencies than to maximise the number of microvolts being delivered to the receiver. 

Loop antennas are a popular choice. They comprise several turns of wire wound on an insulated frame. A variable capacitor resonates the loop on the desired frequency of reception. Maximum response is off the edge of the loop, with nulls broadside (like a magnetic loop but unlike a much larger quad loop element). 

A loop can turn even a mediocre transistor radio into an excellent receiver due to the additional signal, selectivity and directivity enabled. You don't even need a direct wired connection if the radio is placed inside the loop's field. 

Here are some MF receiving loop ideas: 

* Dave's home made loop antennas

* Bruce C's loop antenna page

WA1ZMS Loop for 500 kHz

VE7SL's new LF MF loop Also see Wellbrook Loop

My video demonstrating a loop made from a wooden coathanger

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