The present invention is related to a RMSA (Rectangular Microstrip Patch Antenna)
design for ultra-wide band applications using stepped corners so that it can operate from 3.1
GHz to 10.6 GHz of frequency.
DESCRIPTION OF RELATED WORK
[0002] “Due to the large and rapid advancements in the field of wireless communication there
is a large increasing demand for ultra-wide bandwidth.
[0003] With this increasing demand for antenna’s operating in multiple bands for wireless
communications, the ultra-wide band technology (3.1 GHz to 10.6 GHz) has grabbed much
attention of large number of researchers.
[0004] U.S. Federal Communication Commission (FCC) has approved the license free use of
frequency ranging from 3.1 GHz to 10.6 GHz for ultra-wide band communications in 2002,
then after the researchers have shown keen interest in UWB antenna design
[0005] The UWB is proving the most promising technology to compensate the demand for
high data rates and large bandwidth.
[0006] The first and primary requirement is that the proposed antenna should operate in
specified UWB frequency band i.e. 3.1 GHz to 10.6 GHz completely.
[0007] The shape and geometry of the radiating patch and ground plane is the major concern
for planer UWB antenna designs.
[0008] Various literatures showing different techniques for designing of microstrip UWB
patch antenna out of which some techniques are slots or notches in ground and radiating
patch, stepping, trident feed, patch truncation, parasitic strips, protruded elements, etc. in this
dissertation notching, stepping and beveling is used for designing of UWB antenna.
[0009] Guglielmo Marconi developed the first UWB radio called pulse based spark gap radio
in late 1800’s. The radio systems were used at that time to transmit the Morse codes through
airwaves.
[0010] But by the year 1924, spark radios were not used because strong interference with
continuous wave radio systems.
[0011] Through late 1980’s the UWB technology was termed baseband, carrier free or
impulse technology.
[0012] In mid 1980’s, FCC has approved Industrial Scientific and Medicine (ISM) for license
free wideband communication.
[0013] In the period of nearly 40 years from 1960 – 1999 around 200 papers were published
in IEEE and over 100 of patents were issued on UWB technology for different designs and
types of antennas.
[0014] The most important requirement for an UWB antenna is that it should operate on
entire said frequency band.
[0015] For designing an UWB antenna, various methods like slotted patch, slotted ground,
partial ground, modified feed, truncated corner patch, etc. have been used
2. OBJECTS OF THE INVENTION
[0016] An objective of this invention is to propose a design of rectangular microstrip patch
antenna suited for ultra-wide band applications using stepped corners on both patch
and ground plane.
[0017] In addition to the above, it should also operate over entire said band meant for UWB
i.e 3.1 GHz to 10.6 GHz with the bandwidth of more than equal to 7.5 GHz.
[0018] Another objective is to present a design which can have bidirectional and
omnidirectional radiation pattern.
[0019] Another objective is the compactness of design and ease of fabrication.
[0020] The proposed design show be of low cost.
3. SUMMARY OF THE INVENTION
[0021] ‘Stepping’ means shaping the corners or edges by cutting rectangular shaped
structures.
[0022] The optimal values of the design parameters of the UWB antenna design is described
which is based on the parametric study of all the design parameters.
[0023] The UWB design includes notches, stepped feed and two stepped corners on the feed
side in the first design over the radiating patch.
[0024] Partially modified ground plane with stepped corners is used along with one stepped
parasitic rectangular strip.
[0025] The dimensions of the radiating patch are optimized to achieve the full UWB
bandwidth.
[0026] The best values of various above said parameters were determined by designing the
proposed antenna.
[0027] Fig.1: Parameter variation of design parameter ‘z’
In this parametric study the optimal value of each parameter was chosen and remaining
parameters were optimized by fixing it.
4. BRIEF DESCRIPTION OF THE DESIGN
[0028] The proposed antenna is constructed on FR-4 substrate of 1.6 mm thickness with
dielectric constant of 4.3 and loss tangent (tan δ) of 0.025.
[0029] The stepped microstrip feed of this antenna is divided in two parts of length L1 and L2
with W1 and W2 width respectively.
[0030] The rectangular patch with Wp × Lp dimensions consist of three stepped stairs on two
corners of the feed edge.
[0031] Stepped ground plane results in smooth transition from one resonant mode to another
ensuring good impedance matching and stable gain over.
[0032] VSWR is well below 2 and the return loss S11 is below -10 dB for the said frequency
band.
5. DETAILED DESCRIPTION OF THE STRUCTURE
[0033] Fig. 2: Top and bottom view of the simulated design with design parameters
A novel rectangular planer ultra-wide band antenna (UWB) using one U-shaped and one Tshaped notch with two stepped corners on the radiating patch along with stepped microstrip
feed is proposed.
[0034] The design also includes stepped partial ground with rectangular notch and a coupled
stepped rectangular strip.
[0035] At first, the effect of stepped microstrip feed was investigated and the lengths (L1 and
L2) and widths (W1 and W2) of this uneven structure were optimized for best results.
[0036] Then the dimensions of U-shaped notch is optimized which adds to the bandwidth of
proposed antenna.
[0037] As the values of x and y is increased the peak value of return loss is improved at
lower and the upper frequencies of the return loss curve but this leads to decrease in peak
value of return loss at mid frequencies.
[0038] Length of the U notch i.e. z is controlling parameter of both bandwidth and peak S11.
[0039] As the value of z is increased, the upper frequency peak of return loss curve shifts to
lower frequency and the peak S11 at lower frequency decreases with bandwidth.
[0040] Fig. 3: Return loss S11 plot of the proposed design
The peak value of return loss curve for the proposed antenna is nearly -39 dB.
[0041] Stepped corners are used to improve the electromagnetic coupling between radiating
patch and ground plane by virtue of which the impedance bandwidth of the proposed antenna
is enhanced.

[0042] To achieve fairly good impedance matching the parameter Lg is varied, on increasing
its value the peak return loss shifts to upper frequencies and when it is decreased it shifts to
lower frequencies.
[0043] One parasitic rectangular strip with stepped corners is used in the ground plane to
provide additional current path so that the electromagnetic coupling between patch and
ground plane is improved.
[0044] Fig. 4: VSWR plot of the proposed design
In addition to this, the VSWR is always less than 2 for entire Ultra-Wide Band frequency i.e.
3.1 - 10.6 GHz.
[0045] Fig. 5: Radiation pattern (gain) at frequency 6.85 GHz
The maximum achieved gain is 4.5dB at 8.5 GHz where as for directivity it is 5.48 dBi at 10
GHz.
[0045] It can be easily observed that the gain and directivity increases as the operating center
frequency is increased but with the increasing center resonant frequency the shape of the
radiation pattern degrades.
[0047] So for high gain and high directivity the selection of radiation pattern is also
necessary.
[0048] Stable gain for entire Ultra-Wide Band (UWB) is one of the desirable requirements;
and the gain of the proposed antenna for UWB applications has a gain variation from 2.5 dB
to 4.5 dB in the entire operating range.
[0049] APPLICATIONS OF THE INVENTION
This antenna finds its applications in 5.2/5.8 GHz WLAN, 3.5/5.5 GHz WiMAX, 4 GHz C
band and lower frequencies of X band.
[0050] The impedance bandwidth of the proposed design is nearly 7.5675 GHz.

Claim
We Claim:
1. The proposed antenna operates in a frequency band ranging from 33.0985 to 10.666
GHz with the overall dimensions of 34 (L) × 37.5 (W) × 1.7 (H) mm3
.
2. The system and method as claimed in claim 2, the bandwidth of the design is 7.5675
GHz.
3. The system and method as claimed in claim 3, the material used in this design id of
low cost.
4. The system and method as claimed in claim 4, the design is compact and easy to
fabricate.
5. The system and method as claimed in claim 5, the return loss and VSWR are below -
10 dB and less than 2 respectively.
6. The system and method as claimed in claim 6, the radiation pattern is either
bidirectional or nearly omni-directional depending upon the application.