Patch Antenna

Design and Development of Integrated L & S Band Patch Antennas

A patch antenna is generally low profile antenna. However, in its simple shape of rectangular, circular or square; they are narrowband, limited gain of around 3-4dBi (Typically) at frequency of around 2-3GHz. In order to obtain higher gain, we have to use the array of patches. There are many techniques of array and feed. Similarly, for increasing the bandwidth, aperture coupled is widely used. However, it has the drawback of losses that is, reduced front to back ratio. Other technique used to increase the bandwidth is the usage of thicker substrate. But, it has another problem of surface wave excitation which leads to loss.

The dual band can be created in cost effective design with stack of patches and/or changing the shape. For patches, there are different feeding techniques, but feeding to both patches is simple to obtain dual band with reasonably good bandwidth. Though, single feed is also possible, but individual feed for both bands would be good and simple idea. For side lobe reduction, different techniques like no. of antenna, spacing between antenna, etc. are used. Our attempt would be to minimize the side lobe.

Our experience of designing multiband by changing the shape of patches like combination of inverted F, L, inverted C have resulted in designing around 10 bands antenna from 700-5200MHz frequency. Therefore, it would be possible to design dual band (L and S) with reasonable gain and bandwidth. A sample of design (to show the concept of array, structure and feed) is shown in Fig. below. Please note that it is just a sample. The shape, size, number of elements, arrangement and feed point can be different in actual product. These all depend on optimization and reaching close to design objective. The design will be performed in Candence AWR EM Simulation tool. The substrate FR4 is widely used because of availability and less cost.

We propose:

  • Dual feed (for each band – coaxial probe/connector)
  • Array of patches for each band
  • Series fed array

L-Band Patch Antenna:

Frequency of Operation : 1435-1545 MHz
Gain : Minimum 15dBi

Polarisation : Vertical
Az Beam Width : < 9 deg
Elevation Beam width : 45 deg

S-Band Patch Antenna:

Frequency of Operation : 2200-2300 MHz
Gain : Minimum 18dBi

Polarisation : Vertical
Az Beam Width : < 5 deg
Elevation Beam width : 45 deg
Total Size and Weight:
Size : 65 x 45 mm
Weight : < 8 Kg.

Outputs :
RF Output1 : L Band
RF Output2 : S-band

Note: In the given size you can design antennas L & S patch antennas one above other/adjacent side by/ integrated antenna etc.