ANTENTOP- 01- 2009, # 011

Compact Cage Antenna

Figure 6 Compact Cage Antenna with corner feeding

It can be reached by "opening" the upper loop a bit (Figure 7) or bend the corner of the upper loop by 45-degrees

Figure 7 Compact Cage Antenna with "opened" the upper loop

upward (Figure 8). MMANA file for the antennas (Figure 7- cca_open_corner, Figure 8- cca_bended) may be loaded by link below. You may recalculate the dimensions (using function "Scale" at MMANA) for any frequency you need.

Compact Cage Antenna is a symmetric antenna, so, it is required to feed the antenna using a BalUn. Otherwise coaxial cable feeder would affect antenna input impedance and radiation patterns. As a BalUn we use 5-10 ferrite cores on the coax near the feeding point. You may wind 3-6 turns of the coax on a larger ferrite ring as well (near the feeding point).

Here are some building notes: for example, sides of the CCA for the 10-meters are near 1 meter in length. So, the antenna can be made from a copper or aluminum tube 5-10-millimeters in diameter. For lower bands you may use a copper wire 1-3 mm, stretched by some dielectric frame. For UHF-VHF bands the antenna may be made of any bimetallic conductor.

Some advantages of the CCA:

1. Tiny, toy-like size.

2. Bandwidth similar to usual full sized loop.

3. Gain is close to dipole's gain.

4. All-directional radiation pattern in the

horizontal plane.

Figure 8 Compact Cage Antenna with a corner bended upward

5. Low elevation angle.

6. Low-noise and no electrostatic.

7. Good match to 50-Ohm coaxial.

It could be very interesting to design a phase

antenna arrays either with passive or active

feeding using several CCA's.

However, I leave this for the readers

References:

www.dl2kq.de

Files MMANA:

http://www.antentop.org/011/cca_011.htm

http://www.antentop.org/

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